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ON THE
INFLUENCE
OF
PHYSICAL AGENTS
ON LIFE,
W. F. EDWARDS, M.D. F.R.S.
MEMBER OF THE ROYAL ACADEMY OF SCIENCES, AND ROYAL ACADEMY OF
MEDICINE OF PARIS, OF THE PHILOMATHIC SOCIETY OF THE SAME
CITY, AND OF THE MEDICAL SOCIETY OF DUBLIN, ETC.
Cramilatrtf from tije tfvmci),
BY DR. HODGKIN AND DR. FISHER.
TO WHICH ARE ADDED, IN THE
APPENDIX,
SOME OBSERVATIONS ON ELECTRICITY,
BY DR. EDWARDS, M. POUILLET, AND LUKE HOWARD, F.R.S. ;
ON ABSORPTION, AND THE USES OF THE SPLEEN,
BY DR. HODGKIN ;
ON THE MICROSCOPIC CHARACTERS OF THE
ANIMAL TISSUES AND FLUIDS,
BY J. J. LISTER, F.R.S. AND DR, HODGKIN ;
AND SOME
NOTES TO THE WORK OF DR. EDWARDS.
LONDON:
PRINTED FOR S. HIGHLEY, 32, FLEET STREET,
AND
WEBB STREET, MAZE POND, BOROUGH.
1832.
DEC 5 1917
CT^^
LONDON :
PRINTED ]i\ "STEWAUT AND CO.
OLD JJAILEY,
PREFACE.
It does not appear necessary to say much to urge
the importance of the investigation of the influence
of a variety of physical agents on life, since it con-
stitutes not only a most essential branch of phy-
siology as a science, but is replete with practical
points of vital importance and universal applica-
tion ; seeing they are not less connected with the
preservation of health, than with the cure of dis-
ease. Many of the functions of life are con-
fessedly veiled under an almost impenetrable ob-
scurity. This indeed is so universally admitted,
that the idea of reducing them to the rank of those
phenomena which come within the province of
physics (properly so called) or natural philosophy,
and of applying to them those laws which we
know to regulate operations in which inorganic or
dead matter is concerned, is regarded as hopeless,
and many physiologists, without reviving the auto-
crateia of Stael, nevertheless refer to vitality with
its vires conservatrices as so varying in its powers
a 2
IV PREFACE.
and operations, as to baffle every attempt to reduce
to fixed principles many of those pheenomena of
which it is an element. We cannot be surprised
at this when we consider the almost infinite variety
which life presents in the wide range of the animal
kingdom, and observe how these varieties are mul-
tiplied by those presented by a single species, nay,
by a single individual under various circumstances
of age, season, and situation. We must not, how-
ever, too hastily adopt the idea, that this subject
is really one which presents inherent obstacles of
insurmountable difficulty. Many subjects which
at first appear to be involved in inextricable con-
fusion and perplexity, become clear and intelli-
gible when once the proper clue or explanation is
furnished. Some minds are so happily constituted
as to have a remarkable readiness in perceiving
the relations which connect facts and observations,
which to others appear not merely isolated, but
absolutely contradictory. This appears to be par-
ticularly the case with Dr. Edwards. The labours
of his predecessors had accumulated a vast collec-
tion of invaluable facts and observations, many of
which seemed to be almost annihilated by their
standing in direct opposition to others supported
by equally valid and respectable authority ; the
labours of Dr. Edwards have explained many of
these discrepances. It may be ill becoming in me
to anticipate the judgment of the reader, but I
PREFACE. T
cannot refrain from expressing my admiration of
the patient and clear induction with which the
Doctor proceeds, step by step, through the great
variety of subjects comprised in his work, so as to
maintain the unity and connexion of the whole,
and of the happy art with which he has both
availed himself of the experiments and observa-
tions of his predecessors, and supplied the breaks
and deficiencies which he met with, by well con-
trived simple and conclusive experiments of his
own.
It is at least presumptive evidence of the merit
of the Doctor's work, that different parts of it
presented at separate times to the Academy of
Sciences of Paris, obtained for their Author, al-
though a foreigner, the honourable distinction of
the physiological prize. It is certainly to be re-
gretted, that our philosophical countryman has
not himself exhibited his instructive work in an
English dress, that our medical literature might
have the credit of possessing it as an original -ra-
ther than as a translation. Translations are gene-
rally inferior to original publications. In the pre-
sent instance I have endeavoured to reduce the
weight of this objection by submitting the trans-
lation to the Author's perusal, and be has kindly
supplied me with some fresh matter, which will
be found in the Appendix. Whilst I feel justi-
fied in expressing myself as I have done with
VI PREFACE.
respect to the original work, to which I have to
acknowledge the obligation of much important
assistance in practice, I must confess myself very
differently circumstanced with regard to the trans-
lation.
To suit the convenience of English students,
who have in general neither time nor inclination
for voluminous reading, Dr. Fisher and myself
have laboured, as far as possible, to compress the
work without omitting a single experiment or
conclusion. This, however, has been no easy
task, as Dr. Edwards' own method of exposing
the subjects of which he treats is in general too
concise to admit of abbreviation, without incurring
the risk of producing obscurity.
I have thought it best, in publishing the transla-
tion, to omit the copious tables, in which the Author
has set forth the individual results of his very nu-
merous experiments, to enable the reader to con-
firm the conclusions which he has deduced from
them. These form a valuable addition to the ori-
ginal work, but as I conceive that the majority of
readers will rarely if ever refer to the tables, I
have judged that to reprint them would consi-
derably and needlessly increase the price of the
book. Those who are engaged in similar re-
searches with Dr. Edwards, and are desirous of
referring to the tables, may easily consult them
in the original work, since, as they are almost
PREFACE. VII
purely numerical, they may be easily understood
even by those who are unacquainted with the
French language.
The Appendix to the original work, relates to
electricity in conjunction with the phenomena
of life. It was furnished by Prevost and Dumas,
and is principally devoted to their views respect-
ing muscular contractions, on which subject I
must confess myself under the necessity of dis-
senting from those able physiologists. To the
Appendix, in the translation, I have made some
additions, in order to put the reader in posses-
sion of subsequent researches regarding the re-
lations between life and electricity ; yet it must
be confessed, that this subject is still in a very
imperfect state, and calls for further investiga-
tion, which would doubtless well repay the la-
bour of conducting it.
Some other points relating to physical pheno-
mena connected with life, are also briefly noticed
in the Appendix, viz. : Dutrochet's views re-
specting endosmosis and exosmosis — those of Dr.
Stephens, which have thrown most important
light on the chemical changes produced in re-
spiration and circulation, and the labours of other
experimenters on the same subject.
I have likewise reprinted, with some additions
and alterations, my Thesis on Absorption, a short
paper on the Uses of the Spleen, and the micro-
Vlll PREFACE.
scopic observations of my friend Joseph J . Lister
and myself, in relation to the tissues and fluids
of animals.
The obvious relation which they bear to the
objects of Dr. Edward's work, will, I trust, be a
sufficient apology for the introduction of them.
The notes which are also given in the Appendix,
are few and generally short. For the materials of
the Appendix, I am greatly indebted to the kindness
of my friends, and it gives me pleasure to embrace
this opportunity of acknowledging my obligations
in this respect to Sir Astley Cooper, Dr. Stephens,
Dr. Marshall Hall, Dr. C. Thompson, my valued
friend Luke Howard, C. Woodward and to my
learned and accomplished friend A. R. Dusgate.
I cannot conclude this preface without ex-
pressing a hope, that the students and younger
members of the profession may zealously pursue
the investigation of the various interesting sub-
jects which physiology presents, in the philoso-
phical method of which Dr. Edwards has given
so striking an example.
CONTENTS.
Page
Introduction 1
PART I.
THE BATRACHIAN REPTILES.
CHAP. I.— On Asphyxia 7
Sect. 1. — Comparative Influence of Air and Water upon
the nervous and muscular Systems 9
Sect. 2. — Asphyxia in Water 11
Sect. 3. — Strangulation . . 11
Sect. 4. — Cutaneous Respiration 12
Sect. 5.- — Animals inclosed in solid Bodies 13
CHAP. II. — On the Influence of Tempera-
ture 16
Sect. 1 . — Influence of the Seasons ., 18
CHAP. III. — On the Influence of the Air
CONTAINED IN WATER 22
Sect. 1. — On the Effects of limited quantities of Water... 25
Sect. 2. —Stagnant Water renewed at intervals, ....... 26
X CONTENTS.
Sect. 3. — Action of Aerated Water upon the Skin. ..... 27
Sect. 4. — Running Water 29
Sect. 5. — Limits of this Mode of Life 30
Sect. 6. — Combined Action of Water, Air, and Tempera-
ture 32
CHAP. IV. — On the vivifying Action of the
Atmosphere 35
Sect. 1. — Influence of Cutaneous Respiration 35
Sect. 2. — Influence of Pulmonary Respiration 38
CHAP. V. — The Influence of the Atmosphere
on Perspiration 42
Sect. I. — Loss by Perspiration in equal and successive
Periods 42
Sect. 2. — Effect of Rest and of Motion in the Air .... 44
Sect. 3. — Respiration in Air of extreme Humidity .... 45
Sect. 4. — Perspiration in dry Air 46
Sect. 5. — Effects of Temperature 47
CHAP. VI. — Absorption and Perspiration .. 48
PART II
FISHES AND REPTILES.
CHAP. I.— Tadpoles 51
CHAP. II.— Fishes 56
Sect, I;—- Influence of Temperature on the Life of Fishes,
In Water deprived of Air , ... , ,,.,,,.. . 50
CONTENTS. XI
Sect. 2. — Influence of the Temperature of Aerated Wa-
ter, in limited Quantities, in close Vessels.. 57
Sect. 3. — Influence of Temperature, and limited Quan-
tities of Aerated Water, in contact with the
Atmosphere 58
Sect. 4. — Respiration in the Air 9 59
Sect. 5. — Life of Fishes in the Air 59
CHAP. III. — Lizards, Serpents, and Tortoises 65
PART III.
WARM-BLOODED ANIMALS.
CHAP. I. — On the Heat of young Animals... 68
CHAP. II. — On the Heat of adult Animals.. 75
CHAP. III. — The Influence of the Seasons on
the Production of Heat 81
CHAP. IV.— On Asphyxia 84
Sect. 1 . — Influence of External Temperature .......... 89
CHAP. V. — On Respiration in Youth and
adult Age 91
CHAP. VI.— -On the Influence of the Sea-
sons upon Respiration 98
CHAP. VII. — On Perspiration, or Exhalation 103
Sect. 1. — Loss by Perspiration in equal and successive
Periods 103
Sect. 2. — Influence of the Hygrometric State of the Air 107
Sect. 3. — Influence of the Motion and Rest of the Air. . 110
Xll CONTENTS.
PART IV.
MAN AND VERTEBRAL ANIMALS.
Page
CHAP. I. — On the Modifications of Heat in
Man, from Birth to adult Age.. 112
CHAP. II. — On the Influence of Cold on
Mortality at different Periods
of Life 117
CHAP. III. — Momentary Application of Cold 123
CHAP. IV. — Momentary Application of Heat 125
CHAP. V. — Influence of the Seasons in the
Production of Heat 126
CHAP. VI.— Asphyxia 132
CHAP. VII. — On the Modifications of Respi-
ration DEPENDING UPON SPECIES,
Age, &c 141
CHAP. VIII. — Of the combined Action of Air
and Temperature 145
CHAP. IX. — Effects of Temperature upon
the Functions of Respiration
and Circulation 151
CHAP. X. — Influence of the Respiratory
Movements on the Production
of Heat 157
CHAP. XL— On Perspiration 1 62
Sect. 1 . — Influence of Meals 1 64
Sect. 2. — Influence of Sleep . 1 67
CONTENTS, Xlll
Page
Sect. 3. — Influence of the Hygrometric State of the Air.. 168
Sect. 4. — Influence of the Motion and Rest of the Air . . 169
Sect. 5. — Influence of Atmospheric Pressure 170
Sect. 6. — Perspiration by Evaporation and by Transuda-
tion .... 171
Sect. 7. — On the Influence of Temperature 176
Sect. 8. — Cutaneous and Pulmonary Perspiration .... 178
Sect. 9. — Perspiration in Water 180
CHAP. XII. — Absorption in Water 181
CHAP. XIII. — Absorption in Humid Air 186
CHAP. XIV.— On Temperature 190
Sect. 1. — On the Degree of Heat which Man and other
Animals can endure 190
Sect. 2. — On the Influence of Excessive Heat upon the
Temperature of the Body 195
Sect. 3. — Comparison of the Losses by Perspiration in
Dry Air, Humid Air, and Water, at Tem-
peratures inferior to that of the Body .... 198
Sect. 4. — On the Influence of Evaporation upon the Tem-
perature of the Body when exposed to an
excessive Heat 200
Sect. 5. — On Cooling in different Media, at Tempera-
tures, inferior to that of the Body 202
Sect. 6. — On Refrigeration in Air at Rest, and in Air in
Motion 204
CHAP. XV. — On the Influence of Light upon
the Development of the Body. 206
XIV CONTENTS.
CHAP. XVI. — On the Alterations in the Air
from Respiration 212
Sect. 1. — Proportions of the Oxygen which disappears,
and of the Carbonic Acid produced 216
Sect. 2. — On the Proportions of Azote in the Air inspired
and expired 221
Sect. 3. — On the Exhalation and Absorption of Azote, . 225
Sect. 4. — On the Production of Carbonic Acid in Res-
piration 22q
Sect. 5. — General View of the Alterations of the Air in
Respiration 242
CHAP. XV.— Applications 245
APPENDIX.
On Electricity. By Prevost and Dmnas 285
On Muscular Contractions produced by bringing a solid
body into contact with a Nerve without a Galvanic
Circuit. By Dr. Edwards 307
On Atmospheric Electricity. By M. Pouillet 316
Extract from an Essay on some of thePhcenomena of Atmo-
spheric Electricity, By Luke Howard, F.R.S., Sfc. . . 320
Remarks on the same subject by the Editor, and Experi-
ments and Observations by C. Woodward and P. Smith 325
Be A bsorbendi Functione. By Dr. Hodgkin 342
Further Remarks on the same subject, and Notices of
the Papers of L. Franchini, Fiscinus and Sexier,
Dr. Barry and Fodera 382
CONTENTS. XV
On the Phenomena to which the Names Endosmosis and
Exosmosis have been qiven by H. Dutrochet 414
On the Microscopic Characters of some of the Animal Fluids
and Tissues. By J. J. Lister and Dr. Hodgkin .... 424
On the Uses of the Spleen. By Dr. Hodgkin 448
NOTES.
On Asphyxia 463
On the same subject. By Dr. M. Hall 464
On the Proteus 464
On the Existence of Fish, Sfc. in Water of High Temperature 465
On Hybernating Animals -» 467
On the Temperature of Hybernating Animals and of Young
Animals. By Dr. M.Hall 469
On the Views of Dr. M. Hall and Dr. Holland on this sub-
ject 470
Original Experiments on the Effects of Heat and Cold.
By Sir Astley Cooper 472
Experiments on the same subject, tvith reference to Resto-
ration from suspended Animation. By Thomas Nun-
nelly 475
Observations on the Influence of Temperature on the Mor-
tality of Children. By Dr. M. Edwards and Dr.
Villerme 476
On Cutaneous Absorption. By Dr. Corden Thompson . . 476
Connexion of Rainy Seasons with Disease, exemplified in
the Cases passing through an Hospital 479
On an Increase of the Weight of Atmospheric Air, noticed
by Dr. Prout during the prevalence of Cholera 480
On the Changes effected in the Air by Respiration, with
Notices of the Experiments of Dr. Stevens, S. D.
Broughton, and Allen and Pepys 48 1
ERRATA.
Page 9 line 8 from bottom for heart read hearts.
19 in note for preceding read succeeding.
24 line 9 from bottom for lugs read lungs.
245/or Chapter XV. read Chapter XVII.
331 line 10 from bottom for hogs read dogs.
334 5 from bottom for F. Smith read P. Smith.
448 12/or contribution read contributor.
INTRODUCTION.
The object of the present work is the examination of
the effects of those agents by which we are surrounded,
and whose influence is incessantly exerted upon us. They
are called physical agents, as being the objects of that part
of science which is denominated physics. They are to be
distinguished from mechanical agents.
These researches will relate to the Air in its several
conditions of quantity, motion, or rest, density or rarity ;
to Water in a liquid state, and in a state of vapour ;
to Temperature, as modified both in degree and dura-
tion ; to Light; and to Electricity.
These agents operate simultaneously, and, in general,
imperceptibly, on the animal economy.
The impression produced is the result of their combined
influence. Even when the intensity of any one of them is
such, that we are enabled to distinguish the cause which is
affecting us, it most frequently happens that the sensation
alone is attended to, whilst the accompanying changes
escape our notice. Hence, the most careful observation
of phenomena, as presented by nature, cannot enable us to
analyze the result of such combined actions," and to assign
to each cause its peculiar effect, whilst those effects, which
it is not in the province of sensation to detect, will re-
main undiscovered. By means of experiments, we may,
however, control external circumstances, and vary that
Z INTRODUCTION.
of which we wish to appreciate the action ; and thence, by
observing the correspondence existing between such modi-
fication, and the accompanying change which takes place
in the animal economy, we may establish the relation of
cause and effect. In order to derive advantage from this
method, the intensity of the cause must be determined on
the one hand, and the degree of effect on the other. In
physics we may generally find means of accomplishing
the first : the reader will judge how far I have succeeded
with the second.
I took, for the subjects of my experiments, various species
of animals from all the four vertebrated classes, in order
to give greater certainty to particular results, when an
agent produced uniform effect on beings so differently con-
stituted.
Moreover, I hoped that the investigation of the very
evident modifications, of which certain species are sus-
ceptible, might lead to the discovery of similar modifica-
tions in species in which they are too little marked to fix
the attention in the first instance. I soon found the result
to equal my expectation.
In the detail of my researches I have adhered to the
order in which they were conducted. I have divided the
work into four parts.
The first relates to the Batrachian Reptiles ; the second,
to the other Cold-blooded Vertebrated Animals ; the third,
to Warm-blooded Animals ; the fourth, to Man, and the
other Vertebrated Animals.*
In the outset of these inquiries I soon perceived that the
science of electricity was too little advanced to supply me
with the requisite means for placing the investigation of
* I also made corresponding experiments with several families of
invertebrated animals. M. Adoin,well known by his labours on the
anatomy of insects, assisted me in conducting them.
INTRODUCTION. 3
this on a par with that of other agents. The recent dis-
covery of GErsted, by which the phenomena of electricity
and magnetism are connected, forms, in conjunction with
those of Ampere, and several other natural philosophers, a
new epoch in the annals of this branch of science. The
principles which they have established, and the instruments
which they have invented for the appreciation of actions
hitherto unknown, have furnished Prevost and Dumas
with the means of making some very interesting researches
on electricity, in connection with the animal economy. To
their kindness I am indebted for the concise view of the
present state of our knowledge on this subject, which is
contained in the Appendix to this work.
Tables are added, exhibiting the individual results of the
principal experiments, in order that the reader may be
better enabled to judge of the bases on which the con-
clusions are founded.
The examination of one fact always led me to that of
another ; hence, the intimate connection between all the
phenomena which I have detailed. The importance of the
agent decided the point at which my researches were to
commence. All the physical agents are indeed indis-
pensable to the maintenance of life ; but as the air is that
for which there is obviously the most pressing necessity, I
began by examining the effects which result from the pri-
vation of it. The choice of the animals for experiment
followed as a consequence. Those which offered the
widest scope for observation, with regard both to the
duration of the phenomena, and to the facilities afforded
for variation of the experiments, were the first to be
examined, I therefore commenced with the family of the
batrachians.
They unite many other advantages, which render them
peculiarly adapted to afford the first notions of the influence
b 2
4 INTEODUOTrON.
of physical agents. As they participate in the qualities of
reptiles and of fishes, the knowledge obtained from the
study of them renders it the more easy to pass rapidly to
the other cold-blooded vertebrals.
The minutiae of detail may be collected from the tables
whenever the uniformity of the phenomena is obvious,
whilst the attention is directed to the particular considera-
tion of those instances which at first sight appear to be
exceptions, the examination of which leads to further re-
sults.
The higher temperature of the mammalia and of birds,
being the physiological fact which forms the strongest
contrast between them and reptiles and fishes, I make it
the first point to be considered in the study of warm-
blooded animals ; and, regarding the development of heat as
a function abstractedly, I endeavour to determine what are
the variations to which it is subject, according to various
circumstances with respect to organization on the one hand,
and to external agents on the other. The results of this
examination furnish the elements which enter into a great
number of other phenomena, which are the subjects of sub-
sequent researches.
The commencement of the third part corresponds to the
researches in the first, in which I examine the effects of the
internal temperature on cold-blooded vertebral animals.
I there make no allusion to the facts detailed in the pre-
ceding parts, but confine myself in treating of warm-
blooded animals to the independent consideration of them.
It is only in the fourth part which relates to man, with
the other vertebral animals, that I take an extended view
of the phenomena, as well through the medium of the pre-
viously detailed facts as of others, which serve as the com-
plement to them, or lead to new considerations. It is this
generalization which admits of our entering on the consi-
INTRODUCTION. O
deration of man. This is the end which I proposed to
myself, and to which every thing that I have advanced
leads and refers.
The relations of the physical agents to the animal eco-
nomy are infinite. It was necessary to make a selection.
I have confined myself to those direct actions, which the
present state of the physical sciences furnishes us with the
means of appreciating, and to the examination of their
combinations.
In the choice of the circumstances, of which I sought to
discover the influence, I have always been guided by the
wish to establish principles capable of useful application.
The agents which I have examined, having immediate
relation to the nervous system, and to the organs of respir-
ation, circulation, exhalation, and absorption, I have been
led to the investigation of a great number of facts con-
nected with hygeia and pathology, of which an idea will at
once be formed, when it is considered that I have been
particularly occupied with modifications dependent on con-
stitution, and with the changes which constitution under-
goes through the operation of external agents.
The greater number of the facts which I have related,
were first brought forward in various papers which I have
read before the Royal Academy of Sciences of Paris, or
presented to that body as subjects for the prize founded
for the promotion of experimental physiology. #
* Chap I. The part, On Asphyxia was read to the Academy of
Sciences in 1817. and printed in the Annates de Physique el de
Chimie for the same year, Vol. 5.
Chap. IT. The first part, On the Influence of Temperature was
read to the Academy in 1818, and published in the Annates de Phy-
sique et de Chimie the same year, Vol. 8.
Chap. III. The first part, On the Influence of Air, contained in
6 INTRODUCTION.
I owe the acknowledgment of my obligations to my
pupil M. Vavasseur, who assisted me in the course of my
experiments.
water, was read to the Academy in 1818, and inserted in the An-
nates de Physique et de Chimie, Vol. 10.
Chap. IV. The first part, On the Vivifying Influence of the At-
mosphere—
Chap. V. First part, On the Influence of the Atmosphere on
Transpiration —
Chap. VI. First part, On Absorption and Transpiration in Water,
— were read to the Academy of Sciences in 1819.
These three chapters united to the second part with a short state-
ment of the facts contained in the third, were presented to the con-
cours for the prize of experimental physiology in 1819, and were
crowned by the Royal Academy of Sciences, together with the work
of M. Serres sur les I'Osteogenie in 1820. Baron Cuvier gave an
account of these memoirs in the Analysis of the Transactions of the
Royal Academy of Sciences, published each year.
The 1st and 2d sections of chap. 16. 4th part, are extracted from a
paper which I read to the Academy, January 1821, On Respiration
and the Influence of the Seasons on the Animal Economy ; and which,
being presented to the concours, divided the prize for experimental
physiology with M. Dutrochet's paper. On the Groioth and Repro-
duction of Vegetables.
The 3d section, On the Exhalation and Absorption of Azote,
Chap. 16, 4th part, was read to the Academy in 1823, and printed
in the Annales de Physique et de Chimie, and in Magendie's Jour-
nal de Physiologie ; the 4th section, On the Production of Carbonic
Acid in Respiration ; and the 5th section, A General View of the
Changes in the Air in Respiration — were read to the Academy in the
same year. It will be seen from several parts of this work that I
did not originally intend here to treat of the changes of the air
in respiration, this subject being designed for one of the parts of an-
other work, On the Influence of the principal Chemical Agents.
For reasons which I need not relate, I have concluded to publish
these researches in this place, where they Avill serve as a supple-
ment to those which precede them,
PART I.
THE BATRACHIAN REPTILES.
CHAP. 1.
ON ASPHYXIA.
The action of Air in respiration, is one of the pheno-
mena with the investigation of which physiology was the
first engaged ; but it has been one of the last to be studied
with advantage. The solution of this question depended on
another science which, until latter times, did not furnish
the requisite light.
When Priestley had discovered oxygen gas, and its pro-
perty of converting dark into red blood, and when Lavoisier
had laid the foundation of the new chemical theory, Good-
win made the application of it to asphyxia, and demon-
strated by accurate and skilfully combined experiments that
the exclusion of air, by preventing the conversion of dark
into red blood, is the cause of the death of animals. Bichat
again took up the subject, and has published a treatise on as-
phyxia, under the title of " Researches on Life and Death."
He took a wide view of the subject ; and, by a beautiful
train of experiments, endeavoured to determine the triple
relation of the nervous, respiratory and circulatory systems,
O ASPHYXIA.
He drew the conclusion, that venous blood penetrating the
brain, causes its functions to cease, and that afterwards,
the heart ceases to beat from the same cause.
Legallois likewise treated of Asphyxia in his Researches
on the Principle of Life, and made it appear that venous
blood, acting on the spinal marrow, causes the movements
of the heart to be stopped. It is to be observed, that these
physiologists made their experiments almost exclusively on
warm-blooded animals. The phenomena presented by
cold-blooded animals merited particular attention. Spa-
lanzani took them up in his Researches on the Relation which
the Ah' bears to organized Beings, a work equally remarka-
ble for the number and the importance of its facts. The
alteration which the air undergoes from the organs, capa-
ble of modifying it, was the principal object of his en-
quiry. The relation between the three great functions, on
which Bichat and Legallois have so much insisted, but
little arrested his attention. At that time physiology had
not made the progress which it has done since the labours
of that celebrated experimental philosopher and naturalist ;
and chemistry had not then perfected the process for the
examination of gases. One of the philosophers, who has the
most essentially contributed to this improvement, has also
published a treatise on the respiration of fishes, which
leaves nothing to be desired on this point.*
The phenomena presented by cold-blooded animals are
so wonderful, that it would seem impossible to bring them
together with those exhibited by the other vertebrated ani-
mals. It would not be believed, that they are united by a
common chain, if the careful investigation of nature did
not discover the uniformity of her laws.
* Memoire sur la Respiration des Poissons, by Humboldt and
Provencal, in tbe Memoirs of the Society of Arcueil.
ASPHYXIA. 9
Sect. 1. — Comparative influence of Air and Water upon
the nervous and muscular systems.
Previous to our examination of the phenomena of as-
phyxia, we shall first enquire whether the media in which
it may take place have not a peculiar influence, independ-
ent of that which is exerted over the lungs. Of these
media, the most important are air and water. The singular
power possessed by reptiles of living a considerable time
after the excision of the heart, supplies us with the means
of appreciating the respective influence of these media. By
the removal of the heart the circulation of the blood, and,
as a necessary consequence, respiration, are annihilated.
A part of the blood escapes ; and that portion which remains
may be regarded as a constituent part of the organs. The
nervous and muscular system alone are left, and these are
inseparably connected.
If, after having cut out the hearts of reptiles, taking care
to remove, also, the bulb of the aorta, an equal number be
placed in air and in water, deprived of air, the difference in
the duration of life, if any difference exist under these two
circumstances, will indicate the respective influence of
these media on the nervous and muscular systems, inde-
pendently of that which it may exert on circulation and
respiration. This experiment was performed on salaman-
ders, frogs, and toads.
I cut out the heart of four salamanders of the species
Triton, removing, also, the bulb of the aorta. I exposed
two to the air, and immersed the two others in water of
the same temperature, which had been deprived of air by
boiling. In about four or five hours the salamanders in
the water appeared dead ; but that life still existed was
rendered evident, when they were moved or pinched. One
died in eight hours, the other in nine. Those in the air,
10 ASPHYXIA.
however, lived from twenty-four to twenty-six hours. These
experiments were afterwards repeated with the same pre-
cautions upon six other salamanders, and similar results
were obtained. Consequently air, in comparison with
water, has a superior vivifying influence upon the system
of these animals, independently of its action by means of
circulation and respiration.
The heart and bulb of the aorta were removed from
twelve frogs (R. esculenta and R. temporaria) six of which
were placed in water, deprived of air, and six in air. Those
in the water lived two hours, and those in the air three.
Their activity which continued to be considerable, after the
excision of the heart, decreased far more rapidly in the
water than in air, and stimulation produced much less
effect. The same experiment succeeds equally well upon
toads.
If a frog, thus deprived of its heart, and immersed in
water, be drawn out and exposed to the air, at the moment
when all signs of life have disappeared, it immediately
begins to recover. If it be again plunged in water all ap-
pearance of life instantly ceases ; and it may thus be
made, several times alternately, to lose and recover its
motion and sensibility. This confirms, in a striking man-
ner, the vivifying effect of air, and the deleterious influence
of water on. the nervous system.*
* Nasse has likewise shewn by experiment, that water has the
effect of destroying the irritability of muscles, and has pointed out
an application of this fact to some points of physiology and patho-
logy. This property of water had already been noticed by Humboldt,
and also by Pierson. Note of the Editor.
ASPHYXIA. 11
Sect. 2. — Asphyxia in Water.
In the preceding cases the functions of the nervous and
muscular systems alone remained. In asphyxia, there is, in
addition to these, the circulation of blood, which has been
deprived of the influence of the air. I next attempted to
ascertain the comparative duration of life under these two
conditions, in order to discover the effect which the circu-
lation of venous blood produces on the nervous system.
With this view, frogs, whose hearts had been removed,
and an equal number left entire, were placed in vessels
containing water deprived of air. The result, in all cases,
exhibited a marked difference, sometimes above twenty
hours in favour of the latter. Similar results were ob-
tained with toads and salamanders. The removal of the
air in the lungs, by pressure or excision of the lungs them-
selves occasions no difference in the effects. Hence the
circulation, even of venous blood, is favourable to the action
of the nervous and muscular systems, though incapable of
maintaining life beyond a very limited period.
Sect. 3. — Strangulation.
It may be presumed, that the water which, from the
experiments in sect. L, was shewn to exert a deleterious
influence upon the nervous system, may have prevented
the circulation of venous blood from prolonging life so
much as it would have done in a less noxious medium. I
strangled six frogs, by tying, very tightly, with a pack-
thread round the neck, a piece of bladder fitted very closely
to the head, so as to exclude the air. In fact, the ligature
was sufficiently tight to effect this of itself. At first the
frogs were paralysed, but they afterwards, to a great
degree recovered, and lived from one to five days ; while
12 ASPHYXIA.
the same number in water were dead in ten or twelve
hours. The same experiment upon salamanders was at-
tended with similar results. One of these animals lived
twelve days, when the head became gangrenous ; it af-
forded me an opportunity of making observations anala-
gous to those of M. Dumeril, in his interesting experiments
on a salamander, which survived decapitation a sufficient
length of time for the neck to cicatrize. The phenomena
in these cases being complicated with serious injury of the
the nervous system, belong to a subsequent section. On
comparing asphyxia by submersion with strangulation in
the air, we see so marked a difference in the duration
of life, as to lead to the inference, either that these animals
can live for many days without any other action of the air
than that which is exerted on the nervous system, or that
that fluid acts also upon the blood through the skin.
Sect. 4. — Cutaneous Respiration.
Spallanzani concluded, from his investigation, that when
the skin of these animals (frogs and other batrachians) is
in contact with the air, carbonic acid is produced ; but he
operated upon batrachians whose lungs had been cut out.
In this case the blood from the wound, in contact with the
air, -must necessarily produce carbonic acid. To obviate
this objection M. Chevillot and myself placed frogs,
strangled with bladder and a ligature, as in the preceding
experiment, in receivers containing atmospheric air. We
took them out alive an hour or two after, and having ex-
amined the air of the vessel, we found in it a sensible
quantity of carbonic acid. Hence it follows, that the
length of time which reptiles, in the state of strangulation,
can live in air, must in part be referred to the action of
that fluid upon the skin.
ASPHYXIA. 13
I defer, for the present, the consideration of the mode in
which the carbonic acid was produced.
Sect. 5. — Animals inclosed in solid Bodies.
From the preceding facts and observations, it appears
that animals asphyxiated under water perish sooner than
the mere circulation of venous blood would cause them to
do ; while the life of those in air is prolonged by the influ-
ence of that fluid exerted through the skin. If, therefore,
the animals could be incased in a solid material, which
should exert no deleterious influence on the nervous sys-
tem, the influence of the venous blood would be free from
both these complications. Numerous instances are re-
corded of toads having been found in blocks of stone, and
other similar situations, in which they must have re-
mained, without extinction of life, for an incalculable
length of time. But in these cases there was probably-
some crevice, forming a communication between the ex-
ternal air and the cavity containing the animal.* In 1777
Herissant proved to the Academy of Sciences that toads
could live eighteen months in boxes inclosed in plaster ;
but as, even in this experiment, the animals were surrounded
by the air in the boxes, it is not absolutely conclusive.
I took, on the 24th of February 1817, five pasteboard
boxes of three and a half inches diameter and two deep,
and filled each of them with plaster, in which was imbed-
ded a toad ; one of them was found alive on the nine-
teenth day. The others were left for examination after a
longer period. Similar experiments were tried upon sala-
manders and frogs with the like results ; but these last do
not live so long as the toads and salamanders.
* We are inclined to think that at least in some of these instances
such communications must have been altogether impossible.
14 ASPHYXIA.
The foregoing facts appear still more remarkable, on
comparing the duration of life of some of those animals
exposed to air, with that of others buried in solid bodies.
Four frogs were exposed to the air in a dry bottle. At the
same time, an equal number were placed in dry sand of
the temperature of the atmosphere. I examined them
every twenty-four hours. On the third day all those in
the air were dead, except one, while all those buried in the
sand, with one exception, were perfectly alive.
The life of the animals inclosed in plaster or sand ap-
pears to be preserved by the air having still sufficient
access to them to exert its vivifying influence through the
skin. The permeability of sand is evident. In order to
ascertain how far plaster possessed the same property, I
took an open tube, five inches long and five or six lines in
diameter ; closed one extremity with plaster to the extent
of about an inch, and took care to cover it outside. I let
it dry and again put plaster over it, in order to close the
imperceptible openings which might exist in it. When the
whole was sufficiently dry, the tube was filled, with mer-
cury, and inverted over the same fluid : it was not long-
before I perceived that the air penetrated and lowered the
mercury. This experiment repeated several times had al-
ways the same result, which shews that air freely pene-
trates plaster.
It might, however, have been the case, that the quantity
of air which penetrates the plaster was insufficient to sup-
port the life of these animals. I therefore inclosed frogs,
salamanders, and toads in plaster, as in the preceding ex-
periment, and placed some under water and others under
mercury, to intercept the air, and found that they died
almost as soon as when the water is in immediate contact
with them.
But it remains to be ascertained why the duration of
ASPHYXIA. 15
the life of these animals is longer in the sand or plaster
than in the air ? Frog's and salamanders waste rapidly in
the air, and undergo desiccation. In the proportion that
they waste, their motions are performed with increasing
difficulty ; they move, however, until they have lost the
quantity of water necessary to their existence.
The pasteboard-boxes containing toads and salamanders,
mentioned in p. 13, were opened at intervals of from six
weeks to two months and a half from the commencement
of those experiments. The animals were all dead, and in a
state of complete desiccation. I observed the same of the
frogs which had died in the sand. Hence I concluded,
that in both cases death arose from the loss of the fluids
by perspiration, and I presumed that the perspiration must
be less in the plaster than in the air. This was afterwards
proved by exposing some frogs to the air in dry vessels,
and burying others in dry sand, and afterwards weighing
them, at intervals of two, three, four, and five days, I uni-
formly observed a greater loss in the air than in the sand.
Comparative experiments were also made in air and plaster
upon toads, and the difference was much more striking
than in the sand. Hence the cause of the greater duration
of life in sand or plaster than in air, is from the perspir-
ation being more abundant in the air than in the solid
substances.
Under an exhausted receiver, in which the effects of
rapid evaporation and absence of air are combined, death,
as might be expected, takes place very speedily.
Several experiments which I performed, in* conjunction
with M. Chevillot, on frogs and salamanders, demonstrate
this fact.
CHAPTER II.
ON THE INFLUENCE OF TEMPERATURE.
The facts detailed in the preceding chapter may be
modified by various circumstances, which have not yet
been considered. One of the most important of these is
temperature.
In the months of July and September, 1816. I made
forty-two experiments on the submersion of frogs, in glasses
containing two-tenths of a litre * of aerated water inverted
over saucers.
The mean temperature of the atmosphere was 15.°6 of
the centigrade thermometer, or 60° of Fahrenheit in July,
in September it was 14.° 1 of the cent, or 58° of Fahr.
the temperature of the water was from 17° cent, or 63°
Fahr. to 15° cent, or 60° Fahr. The mean duration of life,
or sensibility to ordinary stimuli was one hour and thirty-
seven minutes in July, and one hour and forty-five minutes
in September.
At the same time I made the following experiments, in
order that the only appreciable difference might be in the
temperature. Spallanzani and some other naturalists had
already observed, that frogs immersed in water lived longer
in winter than in summer, but they had not investigated
the subject.
The temperature of the Seine water being 17° cent, or 63°
Fahr. I cooled it by means of ice to 10° cent, or 50' Fahr.,
* A litre is equal to V76 pint, new measure.
INFLUENCE OF TEMPERATURE. 17
and found that, of two frogs immersed in it, one lived
oh. 50' and the other 6h. 15'. When the water was re-
duced to 0° cent, or 32° Fahr. eight frogs were introduced
into it, and they lived from 6h. 7' to 8h. 18'. When, in-
stead of cooling the water, its temperature was raised to
22° cent, or 72 Fahr., that of the air being 20° cent, or 68°
Fahr., the frogs only lived from Ih. 10' to 35'; when it was
raised to 32° cent, or 90° Fahr. they died in from 32' to
12'; and when it was raised to 42° cent, or 108° Fahr., they
scarcely lived a few seconds, and in no instance exceeded
two minutes.
Hence we may observe that as the temperature of the
water is reduced, the duration of the life of the frogs im-
mersed under it, is prolonged until at 32° Fahr., or 0° of the
centigrade thermometer, it is more than tripled. On the
other hand the elevation of the temperature produces a
corresponding abbreviation of life, till, at 108° of Fahr. or
42° of the centigrade thermometer, death might almost be
said to be immediate. It is worthy of remark that the de-
gree of heat at which frogs cannot survive immersion in
water, is about the natural temperature of warm-blooded
animals.
The temperature about zero appears then the most fa-
vourable to the life of frogs plunged in water, but it must
not be supposed that the prolongation of their life was oc-
casioned by their becoming torpid. They are certainly less
active at that temperature, but they perform the functions
of voluntary motion and enjoy the use of their senses. On
the other hand, the elevation of temperature is accompanied
by a progressive and corresponding diminution in the dura-
tion of life, and a proportional increase of agility.
Analogous experiments on toads and salamanders pro-
duced similar results.
Tn warm climates, animals of this class may perhaps
c
18 INFLUENCE OF TEMPERATURE.
continue to live in water at 42° cent, or 108° Fahr., but
since they would have full liberty of respiration, this fact,
if proved, would not be an objection to the preceding ex-
periments, which have reference to a state of asphyxia.
The influence of temperature with freedom of respiration
will be examined in the sequel.
In reply to an objection which may be raised, that the
speedy death of the frogs might be occasioned by the rapid
transition from the temperature of 15° cent, or 60° Fahr.
to that of 42° cent, or 108° Fahr., rather than to the eleva-
tion of the latter, it may be observed that the transition
was equally rapid in the descending scale.
The considerations, to which the preceding researches
conduct us, are by no means so simple as might at first be
imagined. The influence of climates and seasons, the
mode of life of these animals, the action of the air con-
tained in the water, and the relation which it bears to tem-
perature, and lastly the effect of habit are all accessory
circumstances whose complicated elements exert their re-
spective influences.
Sect. 1. — Influence of the Seasons.
It will be recollected that in the months of July and Sep-
tember, the frogs lived from an hour to 2h. 27' in aerated
water at 15° cent, or 60° Fahr. and at 17° cent, or 63°
Fahr. On the 7th November, ten frogs similarly placed
in water kept at the temperature of 17° cent, or (33° Fahr.
lived from 2h. 5' to 5h. 35'. All the circumstances being
the same in these cases, except the season, it is to this
cause that the difference in the results must be referred.
But in what way does the season produce this effect ?
Is it by means of temperature, or the intensity of light, or
the weight of the atmosphere, or its hygrometric or electric
INFLUENCE OF TEMPERATURE. 19
states, or its degree of motion or rest ? Is any thing to be
referred to changes in habits of the animals themselves ?
The influence of light and electricity must be left out of
the question, until we can appreciate the degree of their in-
tensity. The pressure of the atmosphere which exerts an
influence by affecting perspiration may be disregarded'
since the difference of mean pressure in the two seasons in
which the experiments were made was very inconsiderable.*
The same may be said of the influence of the winds and of
the hygro metric state of the air, since batrachians, though
powerfully affected by these causes whilst living in the air,
are wholly removed from their operation when immersed
in water. The only circumstance, therefore, left for con-
sideration is the influence of temperature, and as the water
in which the animals were immersed was kept at the same
degree in both the series of experiments, it is evident that
the temperature of the atmosphere prevailing at the time
could exert no influence upon the result. The case, how-
ever, is different in regard to the temperature, during a cer-
tain space of time previous to the experiment. The shallow
waters which frogs inhabit, vary in temperature with the
atmosphere and more or less approximate to it. The frogs
submitted to the July experiments had been for the pre-
ceding months under the influence of a mean temperature
of 14°.8 cent, or 58°.6 Fahr., and those made use of in
September had experienced during August, the effect of a
mean temperature of 15°.5 cent, or 60° Fahr. while the
frogs subjected to the November experiments had been for
the previous month exposed to a temperature of 7°.3 cent,
or 45° Fahr. Hence results the remarkable fact, that these
animals were able to live in the latter season twice as long;
* The effects of variation in the rapidity of perspiration, and of
diminished atmospheric pressure in accelerating perspiration, are
shewn in the preceding chapter.
c 2
20 INFLUENCE OF TEMPERATURE.
as in summer in water at the same temperature. Admitting
this to be the uniform result, it necessarily supposes a con-
siderable change in the constitution of these animals,
which thus prolongs the duration of their existence in
water. To ascertain the uniformity of this principle was
the subject of the following experiments.
On the 23d Nov. 1817, the air and water being at 10°
cent, or 50° Fahr. and the mean temperature of the month
being nearly the same ; five frogs were placed in water at
the same degree. They lived from 5h. 10' to llh. 40' ; the
latter period being about double the duration of life of
these animals in water at the same degree in summer. On
the 22d Dec. the thermometer having; been about 0° cent,
or 32° Fahr. for twenty days, three frogs were put in water
at 10° cent, or 50° Fahr. ; they lived from twenty to twenty-
four hours. On the 23d Dec. the temperature being still
0° cent, or 32° Fahr. four frogs were placed in water at
0° cent, or 32° Fahr. the same apparatus being employed
as in the preceding experiments. They lived from twenty-
four to sixty hours.
The experiments just related were frequently repeated
with the same results, for two successive seasons, and
can leave no doubt on the mind respecting, 1st, the in-
fluence of the temperature of the water in which the
animals were immersed, and 2d, the influence of the tem-
perature of the air for some days previous to the experi-
ment. When these causes are combined the effect is
doubled. Hence, in the last-mentioned experiment the
animals were placed in circumstances the most favourable
to the prolongation of their life under water. The congela-
tion of water fixes the limit of the descending scale. In
a greater degree of cold, the conditions are altered, and
belong to the question of asphyxia in solid bodies.
Being desirous of ascertaining whether the influence
INFLUENCE OF TEMPERATURE. 21
of previous temperature would extend itself to the case
of batrachians immersed in water at a high temperature.
I placed, on the 30th October, the mean temperature of
the month having been 7° cent, or 45° Fahr., six frogs
in water, kept at the temperature of 42° cent, or 107° 6'
Fahr. the degree which proves instantly fatal to batra-
chians in summer. But they lived about the same time
as in the analogous experiments made in the summer, viz.
from one to two minutes. I tried the same experiment on
the 23d December, the temperature of the month having
been near 0° cent, or 32° Fahr. and repeated it upon toads
and salamanders with the same results.
CHAPTER III.
ON THE INFLUENCE OF THE AIR CONTAINED IN
WATER.
In entering on this subject, it will be necessary to direct
our attention to the habits of the frog. Spallanzani, from
observations made by himself in the neighbourhood of
Pavia, states, that the frogs there leave the water in Oc-
tober, and withdraw to the sand, in which they provide
themselves with an aperture, called by the frog-catchers,
il respiro della rana, the frog's breathing hole. French
naturalists, however, assert that frogs make their winter
retreat in the water from October till spring ; and M.
Bosc, who has paid great attention to the habits of these
animals, informs us that he has often found them under
water during winter. But do they remain constantly in
this situation? or do they come occasionally to the surface
for the purpose of respiration? This is a question not
easily decided by observation, for however narrowly we
might watch them, we could scarcely be certain that they
had not come to the surface without being observed. Be-
sides, it has appeared, from one of the preceding experi-
ments, that in winter they have lived in water for two days
and a half. From direct observation, therefore, we can
derive little assistance in our inquiry, whether frogs can
during winter, dispense with respiration. The affirmative
side of this question is somewhat supported by the fact,
INFLUENCE OF AIR CONTAINED IN WATER. 23
that they are sometimes found alive in water which is
covered with ice. But this is not decisive, unless it could
also be ascertained how many days had elapsed since the
formation of the ice, and whether it were free from any
aperture. M. Bosc has informed me, that he has seen, in
winter, frogs quit the water for several days in succession,
at a certain hour, and take breath for a short time on
land.
In the numerous experiments which I made in the win-
ters of 1816 and 1817, on the asphyxia of frogs in a limited
quantity of aerated water, they have never lived longer
than two days and a half, even at the temperatures most
likely to prolong their existence during their submersion.
Spallanzani, in one instance, found a frog live eight days
under water, varying in temperature from half a degree to
a degree above zero, cent, and one to two degrees above
32° Fahr. ; he adds, that a more elevated temperature
would inevitably occasion death in the course of a day.
But during the season of the retirement of these animals,
the temperature varies considerably.
It may, perhaps, be supposed that frogs remain torpid
during their hibernation. Torpor, however, does not ex-
empt animals from the necessity of respiration ; but even
admitting the contrary, it has been ascertained by the ob-
servations of M. Bosc and myself, that frogs, though less
active in cold weather, are not torpid even at the tempera-
ture of zero, cent, or 32° Fahr.
Let us now proceed to investigate the influence of the
-air contained in the water. I am acquainted with one ex-
periment only, which has been made in reference to this
subject. Spallanzani placed a frog in water, deprived of
air, and another in a similar quantity of aerated water. The
former was at the point of death in ten hours, but the
latter not until twenty had elapsed. This insulated expe-
24 INFLUENCE OF THE
rinicnt, however, proves nothing, since the difference in the
duration of life might have been occasioned by the different
constitution of the individuals.
The influence of the air contained in water, on the life
of fishes, has been examined with great care by Spallan-
zani, Sylvester, Humboldt, and Provengal ; and their la-
bours have brought to light some most interesting facts,
in reference to the natural history of fishes, but the con-
clusions are applicable to this class of animals only, their
gills being especially designed for receiving the influence
of the air contained in water.
To be amphibious in the strictest sense of the word, an
animal ought to be capable of performing respiration both
in the atmosphere and by means of the air contained in
water; a double faculty, hitherto ascribed to no adult
reptile, except the proteus and the siren. The axolotl,
as Cuvier has shewn, has precisely the organization of the
larva of the salamander. If these singular animals, which
have been united to the family of batrachians, possess, like
tadpoles, the faculty of breathing the air of the atmo-
sphere, as well as that of water, they have also, like them,
the double apparatus of lugs and gills. But, with these
exceptions, the adult batrachians have only lungs, organs
exclusively adapted to atmospheric respiration. There is
nothing, therefore, which should lead us to conclude a
priori, that they are capable of performing both func-
tions.
By the following experiments 1 have endeavoured to
discover how far they are influenced by the air contained
in water.
AIR CONTAINED IN WATER. 25
Sect. 1. — On the Effects of limited quantities of Water,
Several glasses, holding about five ounces and a half, and
filled with water, deprived of air by boiling, and then cooled
to the temperature of the atmosphere, were inverted over
saucers containing about the same quantity of similar water.
An equal number of similar glasses were filled with aerated
water at the same temperature. At the same time a frog
was introduced into each of these vessels, and the dura-
tion of their respective lives carefully noticed. The result
was in favour of the frogs placed in the aerated water, but
it was not very decisive, showing only that the small quan-
tity of water made use of did not contain so much air as
to produce marked and uniform differences. We might
safely, therefore, conclude, that though Humboldt and
Provencal have shewn that boiling in open vessels is not
sufficient entirely to deprive water of the air contained in
it, and that the small quantity which remains is capable of
exerting a marked influence upon fishes ; yet, that in this
instance, no sensible influence could have been produced
from this cause, in consequence of which I judged it un-
necessary to have recourse to the method which they em-
ployed for entirely banishing air from the water which
they used.
I next endeavoured to render the difference more strik-
ing, by increasing the quantity of aerated water.
On the 10th of November, the air being at ll°cent. or
52° Fahr., and the water at 13° cent, or 55° 4' Fahr. six
glasses similar to those used in the preceding experiments,
26 INFLUENCE OF THE
were filled with aerated water, and inverted over the aper-
ture perforated in the shelf of a pneumatic trough, contain-
ing ninety-eight pints and a half of Seine water. A frog was
placed in each glass. At the same time, the same number of
frogs was put into similar glasses of boiled water of the
same temperature, and inverted over saucers. The latter
lived from three hours and forty minutes to five hours and
thirty minutes; while those in the aerated water lived from
six hours and forty-three minutes to ten hours and forty
minutes. The result of these experiments, though satis-
factorily shewing that aerated water has a decided in-
fluence in prolonging the life of these animals, is yet far
from proving that it is capable of doing so to an indefinite
extent.
Sect. 2. — Stagnant Water renewed at intervals.
Although the want of organs specially constituted to act
in the air contained in water, rendered it improbable that
frocks could live in water like fishes, I thought I ought
to leave nothing untried, in order to determine the in-
fluence of aerated water upon their existence in that
liquid.
On the 4th of December, the temperature of the room
being 6° cent, or 43° Fahr., a male frog of the species rana
temporaria, was secured at the bottom of a glass vessel,
holding seventeen pints and a half of Arcueil water, by
means of a transverse wire grating. The next day the
water was drawn off with a syphon till only a sufficient
quantity was left to keep the animal covered, when the
vessel was replenished with fresh water. This was repeated
daily ; the frog not merely survived for eight days, the
longest period for which Spallanzani had been able to keep
AIR CONTAINED IN WATER. 27
a frog alive, in water at 1° or 0° 5., but continued to live
to the 25th of February, that is, for more than two months
and a half, during which period the temperature had varied
from 0° cent, or 32° Fahr. to 11° cent, or 51° Fahr. An
accidental neglect to renew the water occasioned the death
of the animal.
This experiment shows the remarkable fact, that frogs
are really amphibious, since they can not only breathe the
air of the atmosphere, but can also live exclusively by
means of the air contained in water.
Tadpoles, which are possessed of gills as well as lungs,
can also live in water without coming to the surface; a fact
which I proved by an experiment conducted in the same
manner as that which has just been detailed. They cannot,
however, live on land previous to the full development of
their limbs.
Sect. 3. — Action of aerated water upon the skin.
Let us now inquire what is the organ through the me-
dium of which the vivifying influence of the air contained
in the water is exerted upon these animals. We shall first
examine what foundation there may be for supposing that
the water enters their lungs, which' would, in this case,
perform the functions of gills. Inspiration in frogs is per-
formed by a kind of deglutition, and is accompanied by
very evident movements of the throat, and of the soft parts
under the lower jaw. When the animal is breathing in
the atmosphere, their movements are repeated from forty
to one hundred times in a minute. If it be plunged in
water they immediately cease, and whatever be the length
of time during which the submersion is continued, it is very
seldom that any movement of deglutition can be observed.
In the numerous experiments which I have made upon the
28 INFLUENCE OF THE
asphyxia of frogs in aerated water, I have observed these
movements in only a very few instances, and Spallanzani
never perceived them. Humboldt observed that the fre-
quency of the inspiration of a frog in a limited quantity of
atmospheric air was diminished by the introduction of
azote, and that the rarity of inspiration was proportioned
to the quantity of azote introduced ; but neither azote,
hydrogen, nor carbonic acid, has so strong a tendency to
suspend inspiration as water.
These experiments might be deemed sufficient to prove
that it is not through the medium of the lungs that these
animals receive the influence of the air contained in
water.
The importance of the fact, however, induced me to make
a careful examination of the lungs of frogs, which had been
previously immersed in water for a considerable time, and
in no instance could I detect any water in them. This is
likewise confirmed by the experience of Spallanzani.
The air contained in water, therefore, does not act upon
the lungs of the frogs which are immersed in it. Its action
must consequently be referred to the skin, the only other
organ in contact with the fluid.
The question whether this action on the skin is analogous
to that on the gills of fishes, and the investigation of the
changes which these organs effect in the air, belong to a
subsequent part of this work. It will be sufficient here to
state, that during the time in which the life of the animal
was maintained by aerated water, the arteries in the webs
of the feet evidently contained florid blood.
AIR CONTAINED IN WATER. 29
Sect. 4. — Running water.
In the foregoing experiment, the water in which the frog
was placed was at rest. Would life have been equally
maintained in running water? This query would certainly
appear an idle one, had not Spallanzani been led to con-
clude from his experiments, that the animals died sooner
when submerged in running water, than in that which was
at rest in vessels kept in his laboratory.
On the 6th of November, a frog in a net to which a
weight was attached, was sunk to the bottom of the Seine,
at a part where there was about ten feet of water, and was
retained in that situation. On the eleventh, the net was
drawn up, and the frog being found alive and well, was
again similarly sunk. He was afterwards examined on the
seventeenth, when he was found equally lively. At the
very same season, frogs placed in vessels holding five ounces
and a half of water which was left unchanged, survived
only a few hours.
Water salamanders as well as frogs may have life sup-
ported by the contact of aerated water with the skin. A
crested salamander and a green salamander of Latreille,
were confined by means of transverse septa of wire at the
bottom of vessels, each containing four quarts of Arcueil
water changed daily ; they lived about two months, and
the latter died from neglect to change the water, on the
same day that the frog mentioned above, suffered from the
same cause. Both the above mentioned species of sala-
mander bear submersion in water, at the temperature of
zero, without becoming torpid.
As conclusions deduced from experiments on frogs and
water reptiles might not apply to the brown toad, which is
altogether a land animal, an individual of this species was
30 INFLUENCE Of THE
put into a net on the Gth of November, 1817, and sunk in the
Seine. On the 17th he was still living ; but he had made his
escape when the net was again examined a month after.
At the season of this experiment, brown toads as well as
frogs survived only a few hours when confined under the
surface of limited qualities of unchanged water.
Sect. 5. — Limits of this Mode of Life.
The faculty of living by means of air dissolved in water
being shewn to belong to the three genera of batrachians,
which were made the subject of the preceding experiments,
it is important to know the conditions which influence this
mode of life. Are these animals capable of it at all seasons ?
and what is the influence of temperature ? It might be
supposed that when frogs quit their water retreats, they
are no longer able to live under water, since at this season
their constitution undergoes a remarkable change. They
are in a state of the most lively excitation, and certain
parts of their bodies become visibly altered : for example,
the thumb of the male acquires a black colour, and a con-
siderable increase of size. It is the period at which the
species is propagated. In order to ascertain whether, at
this time, frogs continued to retain the power of living
under water, one of these animals was tied by the leg, and
secured at the bottom of a vessel, containing forty-nine
pints of Arcueil water. He lived twenty days, during
which time the water had been changed every twenty-four
hours, and its temperature had never exceeded 10° cent,
or 50° Fahr. Frogs, then, may live under water for a long
time after they are wont to quit it in the spring. Experi-
ment further proved that they possess the same faculty in
autumn.
But is this mode of existence subjected to no limits ? Is
AIR CONTAINED IN WATER. 31
it only necessary to attend to the quality of the aerated
water ? Does temperature, which is productive of so
great an influence when the water is limited in quantity,
exercise none when the quantity is unlimited ?
The frog before mentioned, immersed in aerated water,
which was changed every twenty-four hours, died on the
twentieth day, the temperature not being elevated above
10° cent, or 50° Fahr. This was in the spring of 1816.
In October, 1817, a frog lived under water, in an earthen
vessel, containing forty-nine pints, for eleven days. During
this interval the temperature varied from 9° cent, or 48°
Fahr. to 12° cent, or 53° 6' Fahr., and it was at the latter
temperature when the animal died. These experiments
induced me to attempt others, in order to determine
whether so slight an elevation of temperature could affect
the existence of these animals in aerated water, which was
frequently changed.
On the 12th of April 1 put a frog in a tub containing
fifty-six litres (seven gallons and a half ) of Seine water, at
12° cent, or 53° 6' Fahr., and kept it at the bottom, by
means of a packthread attached to a weight. I found it
dead the next day. I repeated the same experiment for
several successive days with the same result. The tempe-
rature of the water had risen in this interval to 14° cent, or
57° Fahr. I repeated these experiments on toads and sala-
manders, with the same result.
In these experiments, the animals were kept in vessels
containing water which was renewed every twenty-four
hours. But would they experience the same fatal effect
from this slight elevation of temperature, if they were kept
under the water of ponds and rivers, so as not to be allowed
to come to the surface to breathe ? To solve this question
I tried the following experiment : —
On the 12th of April I put seven frogs and two toads into
32 INFLUENCE OF THE
an osier basket, which was immersed in the Seine ; the
temperature of the river, at the surface, was 12° cent, or
53° 6' Fahr. On the 20th of the same month I drew them
out, and of the seven frogs, four were dead, the two toads
were still alive. The temperature continued at 12° cent, or
53° 6' Fahr. The running water was, therefore, much more
favourable to the life of the fross than the water in the
vessels. Could this be attributed to a difference of tem-
perature at the surface and bottom ? To decide this, I
filled a bottle with water, and corked it, I then sunk it where
I had placed the basket, at the depth of five feet and a half.
J drew it out twenty-four hours afterwards, and found the
temperature of the water which it contained exactly the
same as that at the surface. The same experiment, re-
peated several times in this month, gave the same result.
Of the two toads, one died on the 5th of May, the water
at 16° cent, or 61° Fahr., the other on the 19th, the water
at 17° cent, or 62° 6' Fahr. On the 13th of June one of
the seven frogs was still living. During this interval of
above two months, the temperature varied from 12° cent,
or 53° 6' Fahr. to 22° cent, or 70° Fahr. In the first week
more than half the frogs died, between 12° cent, or 53°. 6'
Fahr. to 14° cent, or 57° Fahr. ; one only resisted the tem-
perature of 22° cent, or 70° Fahr.
Sect. 6. — Combined Action of Water, Air, and Tem-
perature.
In the life of frogs under water, there are then at least
three conditions having a powerful influence on their exist-
ence : — 1. the presence of air in the water; 2. the quan-
tity, or the change of water ; and 3. its temperature.
The relation of these three causes deserves particular
notice. We have examined the first with great attention,
CONTAINED IN WATER. 33
and have proved that the air in the water could maintain
the life of batrachians immersed in that liquid. But how
does the temperature act in this case ? Since the air is the
principal condition for prolonging their existence, one might
suppose that the elevation of temperature acts by diminish-
ing the quantity of air.
But Humboldt and Provencal, in their work on the
Respiration of Fishes, have proved that the Seine water
contained the same quantity of air, in the various analyses
which they made of it, from the month of September to
that of February. Now, its temperature varies in that
interval, at least from 0° cent, or 32° Fahr. to 16° or 17°
cent, or 61° or 62° Fahr., which last is higher than that at
which the greater number of the frogs above mentioned
died. Since it is the temperature, and not the quantity of air
which varies, it is to the former that we must attribute the
variation in the effects.
The experiments related in the last chapter perfectly
accord with those which have been just mentioned. By
the former it was shewn, that when frogs are immersed
in five ounces and a half of aerated water, the dura-
tion of their life is inversely proportional to the eleva-
tion of temperature from 0° to 42° cent, or 32° to 107°. 6
Fahr., at which point they die, almost suddenly ; and that
through the whole range of this scale a small number of
degrees is sufficient to produce a great difference in the
duration of their life. It has now been shewn, that the
air contained in the water has a contrary effect to the ele-
vation of temperature. When they are immersed in about
two gallons, changed every day, a temperature between
0° cent, or 32° Fahr., and 10° cent, or 50° Fahr. is not
sufficiently high to counterbalance the vivifying effect of
the air ; but when it rises to 10° or 12° cent, or 50° to 53° 6'
Fahr., the former overcomes the latter, and the animals
D
34 INFLUENCE OF AIR CONTAINED IN WATER.
die, unless the quantity of air is increased. Now the quan-
tity of air may be increased by furnishing, in a given time,
a greater quantity of aerated water ; this was the cause of
some of the frogs in running water resisting the tem-
perature which would be fatal to them in the vessels with
water changed only once in twenty-four hours. But the
influence of the change of the water is very inconsiderable
beyond certain limits ; for, as is well known, water contains
but a small part of its bulk of air ; and according to Hum-
boldt, that of the Seine only ^. These animals, then,
have but one means of resisting the effects of temperature,
and that is, by coming to the surface to breathe the air of the
atmosphere, without which most frogs would die, in a tem-
perature as low as 12° or 14° cent. 53°6. Fahr. or 57° Fahr.
The small quantity of air contained in water under 10°
cent, or 50° Fahr., which is sufficient to support the life of
batrachians in that liquid, produces an extraordinary effect
upon their mode of existence. The extreme activity of
frogs is well known, and there is a striking contrast in this
respect between them and toads ; but keeping them under
aerated water destroys this characteristic. It does even
more ; they become so sluggish in their movements as to
resemble tortoises. The slightest noise, which in their
state of liberty excites a panic among them, at that time
makes no impression. Light, which, on other occa-
sions calls them so easily to the surface, no longer induces
them to rise, when the temperature is sufficiently low.
They have, however, the faculties of sense and motion ;
but in air of the same temperature they are extremely
lively.
CHAPTER IV.
ON THE VIVIFYING ACTION OF THE ATMOSPHERE.
Sect. 1. — Influence of Cutaneous Respiration.
In order to appreciate the influence of the atmosphere on
the skin, it is necessary to suspend the action of the lungs,
by intercepting- the passage of the air to those organs.
As the mouth of these animals, when they breathe, is
necessarily shut, in order to introduce the air into the lungs
by an act of deglutition, it has been thought that this
mode of respiration could be suspended by keeping the
mouth open. In order to determine, whether I could avail
myself of this circumstance for the object which I had in
view, I placed a piece of stick in the mouth of a frog to
serve as a gag : it projected a little on each side ; and was
fastened at its extremities by a thread which passed under
the axillae. I tried this experiment on six frogs, which
were placed under a glass, in a saucer; the edges of the
glass were slightly raised to allow change of air, and a little
water was also introduced into the saucer to supply the
animal with the necessary degree of moisture. The tem-
perature was then 24° cent, or 75° Fahr. In this state,
five died the following day ; the sixth lived seven days.
The state of constraint occasioned by the stick which kept
the mouth open, and the slight compression of the limb
by the thread could certainly not explain this rapidly fatal
result. Respiration was evidently checked, but it was
d 2
36 ON THE VIVIFYING ACTION
not entirely suspended. The movements of deglutition, al-
though less frequent, still took place ; the flanks at inter-
vals contracted. These indications of respiration were suffi-
cient to destroy my confidence in the experiment for the
accuracy of which, a perfect suspension of the communica-
tion between the lungs and the atmosphere was absolutely
necessary.
A ligature passed behind the head can be sufficiently
tightened to completely intercept the passage of the air.
I in this manner applied a ligature to six frogs, and took
particular care to use the most rigid compression, and tied
the ligature several times, so as altogether to exclude the
atmospheric air. The temperature was 12° cent, or 53°.6
Fahr. in the room, and 6° cent, or 43° Fahr. out of doors. I
placed the animals on wet sand. They lived a considerable
time, one of them for twenty days. These animals would
have died in the space of from one to three days, if I had
placed them in five ounces and a half of water, as I proved
at the same season in this and the preceding years. The
influence of the atmosphere on the skin must then have
been considerable, in order to obviate the effects of stran-
gulation for so long a time.
It may be here mentioned that the more rapid termination
of life in the former experiment in which respiration was only
imperfectly suspended, than in the present, is fully ex-
plained by the higher temperature to which they were ex-
posed. The important influence of this circumstance has
already been shown.
The violent operation, however, inflicted in this last ex-
periment must have tended to shorten life; and conse-
quently to set limits to the beneficial influence of the at-
mosphere upon their skin. I, therefore, determined upon
other more effective means of accomplishing my purpose;
this was no less than the absolute removal of the lungs
OF THE ATMOSPHERE. 37
which may be done by a very slight incision, and with
the loss of very little blood. I performed this extirpation
in the middle of December, 1818, on three frogs of mode-
rate size. They did not appear to suffer much, and pre-
sented, after the operation, the same activity as those
which had not been touched. I placed them upon moist
sand. The temperature of the room was 7° cent, or 45°
Fahr., and it rose to 12° cent, or 53°.6' Fahr. on the 17th
Jan. 1819. Two died at this time, having lived thirty-
three days, and the third on the 24th, having lived forty.
If we now call to mind the long duration of the life of
these animals under aerated water which was continually
renewed, and which acts only on the skin, we shall be in-
clined to query, since air dissolved in water serves so well
to maintain their life without the aid of their lungs, ought
not they to find still greater resources in the atmosphere
itself, if we only furnish them with sufficient moisture?
To answer this in the affirmative would be a mere as-
sumption. The comparative influence of the atmosphere
and of aerated water is so little understood, that we can-
not say why fishes live better in aerated water than in
air. Yet the knowledge of this would be of considerable
physiological interest.
I wished to determine whether the operation itself,
in the preceding experiment, did not tend to shorten
life. With this view, on the 4th March 1819, I cut out
the lungs of six frogs, and closed the incision by a suture.
They were placed in a basket with six other frogs, which
had not been mutilated, and immersed in the water of the
Seine, which was then at 4° cent, or 39°.G, but in the space
of a week, it progressively rose to 9° cent, or 48° Fahr.
The greater number of the frogs without lungs died before
the others ; but at the end of the experiment, one of the
frogs deprived of lungs was found alive, with the only sur-
38 ON THE VIVIFYING ACTION
vivor of those which possessed them. The season being-
unfavourable to the life of these animals under water, ter-
minated the experiment on the 15th of March.
These frogs were in every respect similarly circum-
stanced, with the single exception of the operation ; I
therefore, felt myself warranted to conclude, from the re-
sult of this experiment, that since the greater part of the
frogs which had undergone the operation died before those
which had not, the operation must have also contributed to
terminate the lives of those which were placed in the at-
mosphere, in the preceding experiment. Hence it may not
have shewn the utmost duration of life in the batrachians,
maintained by the influence of the air exerted on the skin
alone, but for the present we admit the limit which it has
given us, and proceed to further considerations respecting
the action of the air.
Sect. 2. — Influence of Pulmonary Respiration.
,We have now to resolve the converse of the question con-
sidered in the last section, viz. would these animals live if
permitted to breathe by the lungs alone, the atmosphere
being altogether excluded from contact with the skin ?
A frog was placed in a glass containing five ounces
and a half of water. A wooden cover at the surface
of the water prevented him from coming out, and an
opening which was made in it gave him liberty to breathe
the atmospheric air. The liquid, which he dirtied in a
few hours, was changed every day. The temperature was
12° cent, or 53° 6' Fahr. and it was as high as 24° cent, or
75° Fahr. at the latter period of the experiment. This
frog lived three months and a half, with no other nourish-
ment than the small quantity of water in which it was
immersed. In this situation, the animal has no other
OF THE ATMOSPHERE. 39
direct communication with the atmosphere than by the
lungs. Through the medium of the water, he can, it is
true, receive the influence of the small quantity of air con-
tained in this liquid ; but we have seen in former experi-
ments that where these animals were immersed in the
same quantity of aerated water without being allowed to
breathe at the surface, this quantity of air did not sensibly
prolong their existence. Still, however, there is some room
to doubt, whether this small quantity, which under other
circumstances, might be safely overlooked, may not be
useful in this instance and contribute to aid the action of
the lungs.
The application of a coating to the surface of the body?
naturally suggests itself as a ready method of cutting off
the influence of the air on the skin ; but the moisture and
continued secretion of the skin, renders it nearly or quite
impracticable. The removal of the skin does not get rid
of the difficulty, because none of the batrachians long sur-
vive this severe operation, which is rather surprising, when
we consider how much mutilation they are capable of en-
during.
Oil would answer the purpose of excluding the air if it
were free from objection in other respects. If it be sub-
stituted for water in the glasses with floating covers, as in
the preceding experiments, the frogs die in a short space
of time. The experiment was tried on ten frogs, six of
them lived seven or eight hours, the other four died the
following day. The temperature was at 21° cent, or
70° Fahr. as in the experiments with water. It was also
found that this substance has a deleterious action on the
skin. Some frogs were placed in glasses containing five
ounces and a half of oil, and others in the same quantity
of water, and not allowed to breathe. Those in the oil
made extraordinary movements, and even many attempts
40 ON THE VIVIFYING ACTION
at vomiting ; however they lived equally long in both
liquids. If, in these two cases, instead of suppressing re-
spiration it be left free, the difference becomes considerable.
Water, which contains or absorbs a little air, has a ten-
dency the reverse of that of the oil, and pulmonary respira-
tion with this feeble assistance in the one case, and slight
obstacle in the other, is found sufficient or insufficient to
support life. If then we could confine these animals, in
their relation to the atmosphere, to pulmonary respira-
tion alone, they would be as it were, on the limits of life
and death.
This consideration induced me to inquire if there were
not other animals of the same family, to the support of
whose life pulmonary respiration would not be suffici-
ent, notwithstanding the influence of the small quantity
of air contained in the water. Tree-frogs are animals of
this family ; they differ from common frogs and toads in
having a little cushion at the end of their toes, which en-
ables them to climb perpendicularly on trees, and even on
smooth and flat walls. The species submitted to the ex-
periment is that which is the most common in France. I
made use of the same apparatus as in the preceding ex-
periment, with the addition of a small but loose net, fixed
over the opening in the floating cover. The frog put-
ting its head under the net, breathed in the atmosphere
without being able to escape from the water which sur-
rounded him. Eight of these animals in succession were
submitted to this experiment in the space of five days;
the temperature varied from 17° cent, or 62° Fahr. to 20°
cent, or 68° Fahr. ; there was in each glass only about
five ounces and a half of water, which was changed
several times a day. They did not live, however, beyond
three or four days.
Hence it is evident that pulmonary respiration is not
OF THE ATMOSPHERE. 41
sufficient to support the life of tree-frogs without being
accompanied by the atmospheric influence upon the skin.
The case is the same with the rana obstetricans, on which
the experiment was also tried, and we may conclude that
the observation applies to all the batrachians.
I put seventeen frogs into a vessel containing seven pints
of Seine water permitting them to breathe at the surface j
the temperature was the same as in the preceding experi-
ments. Four days after, seven of them died. I repeated
this experiment on twenty frogs placed in the same cir-
cumstances, adopting the precaution of changing the
water every day ; nine died in the space of three days ;
while others, which were placed in glasses with five ounces
and a half of water, all lived. The difference depended on
the depth of the water. In the glasses, being supported by
the bottom, they breathe ad libitum, but in vessels contain-
ing seven pints, and having a foot in depth, although they
may support themselves for some little time at the surface,
yet, after having expelled a certain quantity of air from the
lungs, their specific gravity being increased, sends them to
the bottom, and they rise and sink alternately, till these
intermissions of respiration, uncompensated by the action
of well aerated water on the skin, puts an end to their
existence. We may therefore conclude, that frogs would
die in deep waters, if they could not occasionally come to
the bank, or find support from time to time on other bodies.
CHAPTER V.
THE INFLUENCE OF THE ATMOSPHERE ON
PERSPIRATION.
The first very perceptible change which animals ex-
perience when placed in the atmosphere, consists in a
diminution of weight, from a vapour which is exhaled
from, or a liquid which transudes through their skin, or
escapes from the pulmonary surface, and is known under
the name of sensible and insensible perspiration. It is this
loss of weight that we are now to appreciate, as well as its
variations, according to certain circumstances.
Sect. 1. — Loss by Perspiration in equal and successive
Periods.
We shall first inquire, What is the relative quantity of
perspiration in equal and successive periods ? Is it vari-
able or uniform? Or, if variable, does it increase or di-
minish according to any fixed law ?
It was very necessary to make this preliminary enquiry,
in order to ascertain the rate of the loss by perspiration,
influenced only by changes depending on the animal itself,
and consequently avoid confounding these variations with
those which depend on external agents.
With a view to determine the relation of the losses of
weight sustained in equal times, I weighed a frog from
INFLUENCE OF THE ATMOSPHERE, &C. 43
hour to hour in air, which appeared calm, the temperature
was carefully noted, and remained sensibly the same
during the course of the experiment. In comparing the
successive losses of weight, a remarkable fluctuation was
observed. The variations were very considerable, in some
cases amounting to double or triple quantities in equal
times : they were usually alternate, without, however, pre-
senting equality in their increments and decrements.
Repeated experiments proved that this phenomenon was
not confined to an individual case, but appeared even in
the different genera of the family which were examined.
This irregularity not depending on any error in the mode
of experimenting, supposes the action of various influential
causes, which do not remain constant in the course of the
experiment. This induced me to give a longer period to
the duration of the experiments, and in weighing the
animals at intervals of two hours, I found a marked ten-
dency to diminution in the quantities lost in equal times.
On comparing them afterwards at intervals of three hours,
the tendency becomes indubitable ; three hours in most
cases proved sufficient to render the diminution constant;
but in a few instances, intervals of nine hours were neces-
sary to arrive at such a result.
This difference, doubtless, depends on a change in the
state of the animal. Now the most remarkable change in
its state is the progressive diminution of the mass of its
fluids ; and in proportion as this is reduced by previous
perspiration, ought the subsequent losses from this cause
to be less considerable. In observing the degree of rapi-
dity with which the loss by perspiration takes place, it
deserves particular notice, that in the intervals of time
employed in the experiments just related, the loss in the
first period was often great in proportion to that in the
subsequent periods, and that in these succeeding intervals
44 INFLUENCE OF THE ATMOSPHERE
its rapidity progressively lessened. Taking the animal at
the point of saturation at the commencement of the experi-
ment, it may be said that it loses by perspiration less and less
in proportion as it removes from this point. Hence it is
obvious, that for a number of experiments to agree in these
results, attention must be paid to the condition of the
animals in respect of saturation. If we compare the
weight of the animals, and the perspiration, without refer-
ence to their state as to saturation, we shall obtain not only
very different, but even contradictory results. We shall
have to return to this subject in the sequel.
Sect. 2. — Effect of Rest and of Motion in the Air.
The fluctuations in the amount of loss by perspiration
as observed from hour to hour, did not arise from any cir-
cumstance dependent on the life of the animal, nor even on
its peculiar organization, since they are found to take place
in pieces of charcoal soaked in water, and exposed to the
influence of spontaneous evaporation, under the same cir-
cumstances, with respect to the atmosphere, as the frogs.
We must, therefore, have recourse to external agents, to
account for the variation. It is well known that the at-
mosphere, even when it appears to us perfectly calm, is
really sufficiently agitated to exercise a perceptible in-
fluence on evaporation. We are, then, naturally led to ex-
amine into the extent of that influence on the perspiration
of animals. For this purpose I hung some frogs in the draft
of an open window, and placed an equal number in the same
room at another window which was shut. The animals
exposed to the open window lost at least the double, and,
according to the intensity of the wind, the triple, and
quadruple of what was lost by those which were placed in
the interior of the room. It was also found, that on sus-
ON PERSPIRATION. 45
pending these animals in vessels, with a wide mouth, to
allow the perspiration to dissipate itself freely in the at-
mosphere, the hourly fluctuations either ceased altogether,
or were very inconsiderable.
Sect. 3. — Respiration in Air of extreme Humidity.
We now come to examine the results arising from the
hygrometric state of the atmosphere ; and in the first place
to consider the question, whether perspiration can take
place in air saturated with moisture ?
To arrive at the solution of this question, it was of
course necessary to remove, as much as possible, the influ-
ence of the motion of the air, and all other disturbing
causes. With this view the animal was suspended in a
glass vessel, inverted over water ; which vessel had been
ascertained, by experiment, to be sufficiently large to obvi-
ate any effect from the alteration of the air by respiration
on the duration of its life.
The experiments were often repeated, the intervals of
weighing were varied considerably, and a diminution of
weight was uniformly observed. It is true, that the che-
mical changes in the air, occasioned by respiration, would
occasion a diminution of weight, in case of this loss not being
repaired ; but particular experiments on the extent of the
respiration of these animals, proved that the slight de-
duction which this cause requires, leaves a greater loss,
which can only be attributed to perspiration. It is true,
that these animals have a temperature of their own,
though it differs in general, but very little indeed, from
that of the bodies which surround them ; and this may
have a slight influence on perspiration in damp air. But
it is the fact rather than its cause which I am here seeking,
and we may conclude, that air saturated with moisture does
46 INFLUENCE OF THE ATMOSPHERE
not prevent perspiration, though it reduces it to its mini-
mum, relatively to all the other causes which we have
hitherto examined.
Sect. 4. — Perspiratiofi in dry Air.
The effects of air as dry as could be procured were after-
wards compared with those of air saturated with moisture.
Several causes prevented the air of the vessel from attain-
ing the point of extreme dryness ; in the first place, the
necessity of commencing the experiment on perspiration at
the same time with the drying of the air in a close vessel,
in order to obviate the passing of the animal through the
mercury into a .vessel containing air previously dried ;
which circumstance might occasion such an increase of
weight as to destroy the effect of the experiments ; add to
this, the perspiration of the animal, which, in air perfectly
dry, changes the hygrometric state of this fluid.
An hygrometer placed in the vessel with the animal, and
a good quantity of quick lime, marked the degree of dry-
ness of the air. On the whole, the effects of calm air pro-
gressively dried during the course of the experiment, was
very remarkable. In the same space of time, all other cir-
cumstances being the same, the perspiration in dry air was
from five to ten times greater than in extreme humidity,
according to the degree of dryness and the duration of the
experiment. If we compare the influence of the hygrome-
tric state of the air with that resulting from its motion, we
shall find, that the agitation of the air, provided it is not
at the point of extreme moisture, may increase the perspir-
ation, as considerably as a drier air in a state of rest.
ON PERSPIRATION. 47
Sect. 5. — Effects of Temperature.
In order to appreciate the effects of mere temperature, it
was of course necessary to reduce to a minimum the influ-
ence of the two preceding causes. Hence, the experiments
made with a view to this object, were performed in a still
atmosphere saturated with moisture.
I compared the influence of temperature between 0° and
40° cent, or 32° and 104° Fahr., which are the limits com-
patible with life, and nearly those of the atmosphere itself.
The general tendency of a rise of temperature was to
equalise the losses in equal times, or in other words to di-
minish the decrements in the quantities lost.
As to the relative influence of different degrees of tem-
perature upon the quantity of perspiration itself, it is much
less than would have been anticipated. During five hours
the quantity perspired at 20° cent, or 68° Fahr., was
scarcely twice what it was at 0° cent, or 32° Fahr. ; that
at 40° cent, or 1 04° Fahr. is seven times greater than that
at 0° cent, or 32° Fahr. ; which resembles the effects obtained
from a dry and still, compared with a humid atmosphere.
CHAPTER VI.
ABSORPTION AND PERSPIRATION.
The present question is, how is the weight of the body
influenced by the contact of water with its external sur-
face ? To render this as sensible as possible in the case of
frogs, they were first placed in air, until they had under-
gone evident loss by perspiration, with the expectation,
that if they absorbed water this absorption would be more
strongly marked, according as they were removed from the
point Of saturation, which was found to be the fact. These
animals, having previously lost a considerable portion of
their weight by perspiration, and being afterwards put in
water of the same temperature as the air, increased in
weight, while the absorption of the fluid was rendered evi-
dent, by the sensible diminution of its quantity in the
vessel in which the animals were placed.
But to what extent does this absorption take place ?
what is its rate of progress and what its limit ? what ensues
when this limit is reached, if the animal be still kept in
contact with the water, a condition to which all these
animals may be exposed, and of which it is important to
know the influence ? It results from the experiments which
I made, that if perspiration in the atmosphere be not car-
ried too far, water will be absorbed, until the loss incurred
thereby shall be repaired. It does not, however, always
cease at that point ; it may, indeed, go far beyond it, be-
ABSORPTION AND PRESPIRATION. 49
fore it arrives at the point of saturation. The quantities
absorbed in equal times, like those lost by perspiration in
the atmosphere, diminish progressively, provided the tem-
perature is not very high. This diminution is likewise
more rapid, according as the animals approach the point
of saturation. It appears, also, that the time required to
repair by absorption the loss occasioned by perspiration, is
shorter than the time during which the same loss is
incurred.
A question still remains. When the body has arrived at
the point of saturation, does its weight remain stationary,
or undergo any further variation ? In seeking for the so-
lution of this question, I found that after the body has
arrived at its point of saturation, there are alternate stages
of diminution and of increase, but the increments do not
pass beyond the point of saturation, at which the diminu-
tion commences. This circumstance is explained by the
fact, that in addition to the aqueous fluid exhaled from the
skin, a portion of solid matter is also excreted. The loss
occasioned by these excretions are at first compensated by
the absorption of the water ; but after some time a real and
progressive diminution is observed to take place.
It is evident, from what has already been stated, that
when one of these animals is placed in water, the weight of
his body will increase or diminish according as either of
the opposing functions of absorption and transudation
predominates over the other. It is interesting to determine
what is the influence of temperature upon the relations of
these functions. It appeared from experiments, that at
0°. cent, or 32° Fahrenheit, the absorption predominates
over the loss of weight ; while at 30° cent, or 86° Fahr.
the losses are greater than the increase by absorption. It
was also observed that elevation of temperature in water
had a marked tendency to augment the animal excretions ;
E
50 ABSORPTION AND PERSPIRATION.
from which we seem authorized to conclude that an ana-
logous effect would be produced upon perspiration in the
air. On the other hand, the motion of the air, exercising
little, if any chemical agency, would have less influence
than temperature upon the excretion of animal materials,
and consequently contribute more to the production of the
aqueous portion of perspirable matter. The effects of
dryness and moisture would also seem to have less
influence than temperature on the loss of the animal
matters.
PART II.
FISHES AND REPTILES.
CHAPTER I.
TADPOLES.
In treating of the family of the Batrachians, the first
stage of their lives, during which they have a peculiar
form and distinct functions, has been slightly passed over.
And since their mode of life at this period, in many re-
spects, resembles that of fishes, I have reserved the exa-
mination of it until I should come to treat of this class of
cold-blooded animals. The most important peculiarity of
tadpoles is not that which depends on their external con-
formation, the absence of limbs, and the presence of a tail ;
but that which results from their possessing two kinds of
respiratory organs, lungs and gills. Tadpoles unite, in regard
to respiration, the functions of reptiles with those of fishes;
their use of them varies not only according to their deve-
lopment, but also according to their physical conditions,
under the influence of which we are now about to consider
them. The tadpole has, in common with the adult animal,
the power of supporting life through the medium of the
skin, by means of the air contained in water. It has
e 2
52 TADPOLES.
already been shewn that the limits of temperature in which
the adult animals are able to exist, are 32° and 50° F. or
0°. and 10° cent., and that beyond the higher limit, the
greater part were obliged to have recourse to atmospheric
respiration ; but tadpoles having an additional organ, by
which they are enabled to avail themselves, in a higher
degree, of the vivifying influence of the air contained in
water, ought, one would imagine, to support, under
water, a much greater elevation of temperature, without
having recourse to the external air. That this is actually
the case, is shewnby experiments, in which they were kept
a long time in vessels with the water occasionally changed,
and in running water, at the temperature of 25° cent, or
77° Fahr.
The most important point in our enquiries respecting tad-
poles, is the influence which physical agents may exert on
their transformation. The action of these agents on the form
of animals, is one of the most curious questions in physiology.
One of the conditions which is best known, is the necessity
of aliment for the development of forms. This is the reason
that when we wish to hasten the metamorphosis of tadpoles,
we take care to mix with the water in which they are kept
a small quantity of nutritious substances, and to change the
liquid, that the decomposition of these materials may not
prove fatal to them. On the other hand, their transform-
ation is retarded, when the supply of nourishment is scanty.
Temperature is another condition, the influence of which
is generally known. We are aware that tadpoles change
in warm seasons : but it is a fact not so generally known,
that in our climate a great many are not changed the
same year. This happens to those which are produced
late in the summer. The subsequent temperature not being
sufficiently high, they pass the winter in the state of larva,
and do not quit it until the return of warm weather. These
TADPOLES. 53
are the only influences which have been hitherto ascer-
tained with regard to the developement of these animals.
There is another which I have endeavoured to determine,
and to which I have been led by my experiments on the
adults : it is, the effect which atmospheric, compared with
aquatic respiration, exercises on the form of these animals
in their earliest age. The difference which these two
modes of respiration occasioned in the activity of the adult
animal, induced me to conceive, that limiting the tadpole
to aquatic respiration would tend to continue its original
form. With this view I procured a tin box, divided into
twelve compartments, each of which was numbered and
pierced with holes, so that the water might readily pass
through the box. A tadpole, (which had been previously
weighed) was put into each compartment, and the box
was then placed in the river Seine, some feet below the
surface. A larger numbei was at the same time put
into an earthen vessel, taining about four gallons of
Seine water, which was hanged every day. These
tadpoles were at liberty to rise to the surface and respire
air, and they soon went through their metamorphosis. Of
the twelve placed in the box under water ten preserved
their form, without any progress in their transformation,
although some had doubled, and others trebled their
weight. It should be observed, that at the time when the
experiment was begun, the tadpoles had acquired the size
at which the change is about to take place. Two only
were transformed, and this very much later than those
which, in the earthen vessel, had the liberty of respiration
in air. The want of atmospheric respiration appeared here
to have a marked influence, but we had not the means of
accurately informing ourselves of one very influential cir-
cumstance, that is, the supply of nourishment. In the
river the water is renewed incessantly ; and frequently ve-
54 TADPOLES.
getable and animal substances must necessarily be more
abundant in it, than in the water of a vessel which is
changed only every twenty-four hours. Notwithstanding
this difference in favour of the tadpoles deprived of atmo-
spheric respiration, it had influence upon two only ; the
other ten underwent no change.
It would appear to result from these facts, that the
young animals, with double respiration, would retain their
original form under water, if their nutriment were not
too abundant, and the temperature were not too high ;
and that the difference of atmospheric respiration alone,
joined to these circumstances, would determine the trans-
formation.
This conclusion, at first, appeared to me to be strictly
correct ; but there was an element which I had not taken
into account ; namely, the absence of light : for the tad-
poles, which were in the tin box, were deprived of light as
well as of atmospheric air. For the present, we will rest
satisfied with the conclusion that, under these two priva-
tions, tadpoles are retarded in their transformation ; but we
shall return to the subject in another part of this work, in
which the influence of light is considered.
There are three remarkable animals, which have a strong
affinity to tadpoles, and have been considered as belonging
to the family of batrachians, these are the axolotl, the siren,
and the proteus. We are indebted to Cuvier for some
valuable investigations respecting the structure of these
animals. According to him, the axolotl has the anatomical
characters of the larva of the salamander ; and the siren
and proteus are species of different genera from each other.
In the proteus, the lungs, he says, are little more than ru-
dimentary. These animals are all furnished with a double
respiratory apparatus, lungs and gills ; but the pulmonary
organ of the proteus is, as we have said, in an imperfect
TADPOLES. 55
state. It is possible, that the result of the preceding re-
searches might be applicable to these animals. It would
be desirable to ascertain the effect of the united influence
of increased nourishment, elevation of temperature, aerial
respiration, and the presence of light, on the axolotl, and
the siren ; and to examine whether the exercise of the
lungs, by a frequent use of atmospheric respiration at the
surface of the water, would not tend to suppress the bran-
chiae, as happens to the young batrachians, when tempera-
ture and nutrition are favorable. It may be remarked,
that the proteus has been always found placed in those
conditions as to temperature, darkness, and respiration, in
which the branchiae remain. In fact, it inhabits the sub-
terranean waters of the lakes of Carniola, in which it can-
not perform atmospheric respiration, and where the tem-
perature is, perhaps, sufficiently low to preserve the bran-
chiae. The last point of view under which it remains to
examine tadpoles, relates to their existence in air : but this
subject being intimately connected with the life of fishes
in the air, will be examined when I treat of that class of
animals.
56
CHAPTER II.
FISHES.
The labours of Spallanzani, of Sylvestre, and of Humboldt
and Provencal, have made us more accurately acquainted
with the physiology of fishes than with that of any other
cold-blooded animals. I shall not attempt to detail the
result of their researches, most of which are foreign to my
present subject. I have only to consider fishes in relation
to those points which bear on the phenomena already pre-
sented to us by the batrachian reptiles.
I shall first examine the influence of temperature.
Sect. 1. — Influence of Temperature on the Life of Fishes, in
Water deprived of Air.
To arrive at a correct result, we must firrst reduce the cir-
cumstances of the experiment to their greatest simplicity.
For this reason I shall commence by enquiring into the
effect of temperature on fishes in water deprived of air.
Comparative experiments were made on individuals of the
same species, and with as close a resemblance as possible,
at temperatures varying from 0° cent, or 32° F. to 40° cent,
or 104° Fahr. The result was, that at the higher limit death
was speedy as with the batrachians, and the duration of
FISHES. 57
life progressively augmented in proportion as the tempera-
ture was diminished to the lower limit. It is here seen
that the effect of temperature (excluding all other influ-
ences) is altogether analogous to what has been observed
in the batrachians ; that the limits of the shortest and
longest duration of life in the batrachians and fishes placed
in water deprived of air, are alike in both ; and that in
the same range of temperature, from 0° cent, or 32° F. to 40°
cent, or 104° Fahr., the duration of their life goes on augment-
ing or diminishing, according as the temperature falls or
rises between these extremes.
In regard to the differences which fishes of the same
species present at the same degrees of temperature between
these limits, size has a marked influence, the smallest as
well as the youngest are those which are the least capable
of bearing an elevation of temperature. However different
may be the duration of the life of small fishes at low tem-
peratures, at 40° cent, or 104 Fahr. it is almost uniform in
all. They scarcely ever live more than two minutes ; but
the larger fishes are able to survive several minutes longer.
Sect. 2. — Influence of the Temperature of Aerated Water,
in limited Quantities, in close Vessels.
On varying, in a series of experiments, the temperature
and quantities of aerated water, it appears,
1st, That the duration of life goes on increasing with
an increase of the quantity of aerated water, the tempera-
ture remaining the same.
2. That the same result takes place when, the quantity
of water remaining the same, we lower the temperature.
3. That the duration of life remains the same, when, within
certain limits, we increase or diminish, at the same time,
both the temperature, and the quantity of aerated water.
58 FISHES.
Sect. 3. — Influence of Temperature, and limited Quantities
of Aerated Water, in contact with the Atmosphere.
Sylvestre has ascertained that a limited quantity of
aerated water, in which a fish is placed, absorbs the air in
contact with its surface. It evidently follows from this
fact, that the life of the animal, in a limited quantity of
water, will, ceteris paribus, be the longer, the more fully the
absorption of air by the water compensates for that which
the animal consumes in the water. Add to this, that the
fish, when free, is able to derive directly from the atmo-
sphere fresh supplies of air, according to its wants.
Let us now see the influence of temperature under these
circumstances. Take for example a bleak (cyprinus albur-
nus). If we put it into a vessel with a large mouth, con-
taining five ounces and a half of aerated water at 20°
cent, or 68° F. in summer, it dies within a few hours : but
when the temperature is lowered to 10° or 12° cent., or 50°
or 53° F., and is kept at that degree, the animal lives until its
secretions are so abundant as to corrupt the water. If, to
remedy this inconvenience, we merely renew the water
every twenty-four hours, the animal lives in it almost inde-
finitely.
This is exactly what we have seen to take place with
the batrachians. Between 0° cent, or 32 Fahr. and 10° or
12° cent, or 50" or 53° Fahr. they live an indefinite time in
aerated water, provided it be renewed sufficiently often ;
but they die for the most part as soon as the temperature
rises above this limit.
Let us now examine the general result of these facts, not-
withstanding the different conditions in which the animals
are placed. The more the temperature is raised beyond
certain limits, the greater is the degree of the influence of
the air required for the support of life. This influence,
FISHES. 59
without reference to other causes, will be great in propor=
tion to the quantity of this fluid. Here, however, there
are limits depending on the organization of the animal.
Sect. 4. — Respiration in the Air.
As yet we have only considered the respiration of fishes
in water : their respiration in air deserves particular atten-
tion. When a fish, in a given quantity of aerated water,
has reduced the proportion of air until its respiration has
become difficult, it rises to the surface and takes in air from
the atmosphere. In order to show that atmospheric re-
spiration has an influence on the life of fishes, Sylvestre
placed a diaphragm at the surface of the water, to prevent
the fishes from taking air directly from the atmosphere.
He observed that in this case fishes die sooner than when
they had access to the atmosphere, which proves that they
can breathe air, and that this mode of respiration tends to
prolong their life in water.
Sect. 5. — Life of Fishes in the Air.
We now proceed to the examination of a new circum-
stance in respect to the life of these animals ; viz. their
existence in the atmosphere. This, as regards the influence
of physical agents, is the most obscure point in the life of
fishes. It is also a condition in which they present phe-
nomena which do not appear in any way to accord with
those presented by animals breathing air. When we take
a fish out of the water, -we see it, according to its species,
die in a few minutes, or in a few hours. It is not then
surprising that fishes should have been considered inca-
pable of living by atmospheric respiration, and that this
should have been attributed to the greater density of the
air existing as atmosphere, compared with that contained
in solution in water. Air does, undoubtedly, act differently
60 FISHES.
according to its density, on living beings. It is also true that
the greater part of vertebrated animals quickly perish from
the opposite transition, by passing from the atmosphere
into aerated water ; but in this case it is evident, that
they die because they have not sufficient air; and we
might suppose that fishes die in the atmosphere because
they have too much. Having already stated the proofs by
which Sylvestre has shewn the influence which the respi-
ration of air exerts in prolonging the life of fishes in water,
I may proceed with these animals as with others in the
examination of the changes which they undergo by ex-
posure to the atmosphere.
A chub, (cyprinus jeses) and a gudgeon, (cyprinus
gobio) were first wiped, then weighed, and exposed to the
air. Their gills continued to beat until death. The sur-
face of their bodies gradually dried, and at the time of
their death they were stiff, and dry. On weighing them
again, I found that they had lost by perspiration, the one,
one-fifteenth, and the other, one-fourteenth of its weight.
This result is nearly the mean of experiments made on other
species.
Having in our researches on the batrachians seen the in-
fluence of loss by perspiration from exposure to air, we
shall now apply it to the case of fishes. To simplify the
examination of this subject, let us here consider, as we
have done in our researches on the batrachians, the losses
by perspiration, as solely at the expence of the water con-
tained in the animal. Capacity of saturation with water
implies the quantity of this liquid which an animal is able
to contain, between the point of greatest repletion, or satu-
ration, and that of the greatest inanition, compared with
the weight of its body. The means of carrying the body
to the point of saturation when it is capable of absorbing-
water, is to place it in that fluid, until the increase in
FISHES. 61
weight has arrived at its maximum. This is exactly the
condition in which fishes are found in their natural state,
and on removing them from the water in which they live,
we may regard them as saturated with this liquid, pro-
vided they are in a state to absorb it. Now we shall take
for the measure of their capacity of saturation with water,
as we have hitherto done in regard to the batrachians, the
loss which they experience by perspiration before death ;
and we see it is sufficient to ensure the death of fishes,
that they lose the fourteenth or fifteenth part of their
weight. If this loss appear too inconsiderable for us to
ascribe the death of these animals to it, let us compare this
result with those which we obtained in our researches on
the batrachians. They were not given in the preceding
chapter, that they might be reserved for this occasion. It
has been shewn that the point of saturation with water, in
the case of batrachians, depends on the state of their nu-
trition, and that it may vary within very considerable
limits. Now the losses which they undergo by perspiration
vary in the same manner. In conditions favourable to nu-
trition, their capacity of saturation may equal the third of
their weight ; but, in unfavourable conditions, it is so
small, that the least appreciable loss is sufficient to cause
death. On applying these results to fishes, whose capacity
for water is small compared to that of batrachians, we shall
see that the loss which they experience by evaporation is
enough to cause their death in air. But the phenomena
relative to this subject are not always so simple; they may
be very complicated : one might be led to believe that at-
mospheric respiration would keep fishes alive if we could
devise means for obviating their loss of weight by evapo-
ration. With this view, a fish which had been wiped and
then weighed, was suspended in a limited quantity of
aerated water, so that it had its head and gills above the
62 FISHES.
surface ; it died in nine hours and twenty-one minutes.
On then weighing it again, it appears that it had not sen-
sibly diminished in weight, but on the contrary had
slightly increased. This result would appear to be inde-
pendent of the cause we have before assigned for the death
of fishes, where the whole body is exposed to the action of
the atmosphere. But before enquiring into the influence
of a new cause which may be added to the first, let us
more attentively examine the complicated case in which
fishes are found in the circumstances of the experiment last
related. The body is plunged in water, but the head and
gills are exposed. On one hand absorption takes place in
the water, on the other, perspiration in the air. The ab-
sorption by the body plunged in water is proved by the
slight increase of weight which takes place during the ex-
periment, and the loss by perspiration from the part ex-
posed to the air is demonstrated by the preceding experi-
ments. Now it is evident, that the organ of respiration,
which is exposed to the atmosphere, cannot continue its
functions unless the losses by perspiration are repaired. It is
true the rest of the body absorbs, and that, on the whole, it
does not lose any of its weight ; but this condition is not
sufficient for the continuance of respiration. It is also ne-
cessary that the distribution of the fluid absorbed by the
trunk, should be such, that the gills and muscles which
move them should receive a proportion of it capable of re-
pairing the loss which those organs experience by perspi-
ration. Presuming it possible that this equilibrium might
not take place, I made the following experiment to enquire
into the relations of partial and simultaneous perspiration
and absorption. I placed some fishes in the opposite
position to that of the fish employed in the last experiment,
that is, with the head and gills in water of the same
quality and quantity, and the trunk, suspended in the air
FISHES. 63
by a thread passed through the end of the taiL They lived
in this state many days. I weighed them after that inter-
val, and discovered that there was evidently, in this case,
a slight increase of weight. But the drying of the surface
of the part of the trunk exposed to the air was as marked
as in the case where these animals were entirely exposed to
the atmosphere, and where they died after a considerable
diminution in weight. It is therefore evident that the fluid
absorbed by the gills was not distributed to the rest of the
body in a proportion sufficient to repair, in all parts of the
trunk, the loss which it had sustained by perspiration in air.
The following fact, relative to the physical conditions of
fishes in air,is important in the consideration of the principal
causes of their death when so placed. Some fishes, when
exposed to the air, soon cease to move their gills, although
they continue to live pretty long afterwards ; but they die
much sooner than those of the same species whose gills
beat to the last. Suspecting that this difference in the
duration of life proceeded from the interception of the air,
I remedied it by raising the gills by a small peg placed be-
neath them. The branchiae were thus exposed to the air.
This change of condition, in relation to the atmosphere,
proved sufficient to protract life as long as in those cases
in which the respiratory movements were continued spon-
taneously. The effect of thus raising the gills is so con-
siderable, that if the gills of a fish, out of water, have
quickly ceased to beat, we may, by its means, restore, for
a while, their spontaneous action, and even do so for several
times in succession. We see, therefore, that the life of
fishes in the atmosphere, depends on several conditions ; of
which the principal are, temperature, the capacity of sa-
turation with water, the corresponding loss by perspiration
from the trunk and gills, the quickness of this loss, the ac-
tion of the muscles which move the gills, and the use
64 FISHES.
which they make of their muscles to avail themselves of
the action of the air upon the gills. In short, they come
under the general law, relative to the influence of the atmo-
sphere on the life of vertebrated animals. As fishes seem
to form an exception to this law, I have thought it neces-
sary to shew that they are so only in appearance. What
has been here stated relative to the life of fishes in the at-
mosphere, is equally applicable to tadpoles, placed in the
same circumstances. They die from the quantity of water
which they lose by perspiration, and although their capa-
city of saturation is, at least, equal to that of frogs, since
it varies between one-third and one-fourth of their weight,
yet, as their size is very small, and their perspiration rapid,
on account of the delicacy of their skin, they soon lose that
proportion of water, and in the experiments which I made,
I found that thev did not live more than four hours.
65
CHAPTER III.
LIZARDS, SERPENTS, AND TORTOISES.
The cold-blooded animals which remain to be examined
are the families of lizards, serpents, and tortoises ; in other
words, the saurian, the ophidian, and the chelonian
reptiles. The species employed in my experiments were
the grey lizard, the ring-adder, and the rat-tailed and
the mud tortoises, which served as types of their differ-
ent families. The external covering of all these cold-
blooded animals like that of the batrachians, receives a
vivifying influence from the contact of the atmosphere, and
thus concurs with the pulmonary respiration to support
their existence, as connected with the influence of the air.
The isolated influence of pulmonary respiration in lizards,
serpents, and tortoises, presents the same differences as in
the batrachians, i. e. in summer it is sufficient with some,
and insufficient with others for the continuance of life.
The families to which pulmonary respiration is in general
sufficient are serpents, and tortoises. In lizards, on the con-
trary, it does not, in summer, suffice to maintain life, The
same experiments were made on these animals, as on the
tree-frog, and the rana obstetricans, and with the same re-
sult : but it was much more remarkable, in as much as their
skin being scaly, would certainly not induce us to presume
that the action of the air on that organ was so necessary
for the preservation of their life. If we enquire into the
general cause of these differences in the batrachians and
66 LIZARDS, ADDERS AND TORTOISES.
other reptiles, we find it in the varied proportions of the
lungs. I have proved that among the species submitted to
this kind of experiment, those in whom pulmonary respira-
tion is sufficient are the frog, and the brown toad, and that
of Rcesel ; these are precisely the species in which the
lungs are proportionally the largest. Now, as it has been
shown by multiplied experiments that pulmonary respiration
alone was scarcely sufficient in summer to maintain the life
of these animals, and that it required only slight obstruc-
tions to occasion their death, it follows that inferiority in
the extent of the lungs, in other species, would produce the
same effect when they are limited to pulmonary respiration.
We see the same circumstance giving rise to the same re-
sult in other reptiles. Tortoises and serpents are similarly
circumstanced with the frog and common toad : pulmonary
respiration alone appears sufficient for them, but lizards die
in summer in a few hours if we confine them to pulmonary
respiration, and suppress the vivifying action of the atmo-
sphere on the skin. There is a marked difference in the
proportionate extent of their lungs, and those of serpents
and tortoises. We see then that, as respects the action of
the atmosphere, the general results are the same with all
cold-blooded animals. The modifications of the vivifying
action of the atmosphere on the external surface of the
body, all reduce themselves, on taking the phenomena in a
general point of view, to the physical conditions of the ex-
ternal covering. The same may be said of the physical
agents which we have examined with reference to perspira-
tion. We shall therefore consider the influence of the ex-
ternal covering as respects its porosity and thickness, in
relation both to the vivifying influence of the atmosphere,
and to perspiration. We have seen that the batrachians
can live in solid coverings surrounding them on all sides,
provided these coverings are so porous as to admit a suffi-
LIZARDS, ADDERS, AND TORTOISES. 67
cient quantity of air. I showed that these animals lived a
long time in plaster exposed to the air, notwithstanding
the thickness of the covering; but in pursuing these re-
searches, I afterwards discovered that the quantity of air
which they receive through plaster, is only under certain
circumstances, sufficient for the maintenance of life. It is
evident that through these coverings the proportion of air
which they receive in a given time, is less than when the
skin is exposed. For this reason they cannot live under
running aerated water, when enclosed in solid bodies,
although they do so very well without such a covering.
In the same way, lizards, serpents, and tortoises, in the ex-
periments which I have made on this subject, were unable,
on account of the thickness of their natural coverings, to
live under running aerated water. The same cause has an
equal influence on perspiration. We have seen, in the
first chapter, that when the animals are surrounded by a
solid covering, they perspire much less than when the
bare skin is exposed to the air. In like manner lizards,
serpents, and tortoises, on account of the scales with which
they are covered, perspire much less than the batrachians.
From these differences dependent on the coverings of the
body, arises the variety which we observe in the duration
of the life of these animals when deprived of nourishment.
This diversity depends on the rapidity or slowness of per-
spiration, as is proved by the numerous and varied experi-
ments which I have made on the duration of the life of
batrachians, under different circumstances with respect to
perspiration, among which the effect of solid coverings was
the most remarkable. The influence of temperature on the
duration of life in lizards, serpents, and tortoises, is analo-
gous to that which I have already shown to be the case
with batrachians and fishes.
f2
PART III
WARM-BLOODED ANIMALS.
CHAPTER I.
ON THE HEAT OF YOUNG ANIMALS.
It is a general opinion, inferred from the circulation be-
ing more rapid and the nutritive function more active in
young animals, that their temperature is likewise more
elevated than that of adults. But this opinion not being
founded upon direct observation, I turned my attention
to it at the commencement of my researches on animal
heat. By means of a thermometer placed under the axilla,
and the bulb applied so as to be on all sides in contact with
the animal, I ascertained the temperature of some new-
born puppies whilst in the act of sucking, and found it to
be nearly equal to that of the mother, about a degree or
two lower; but as this difference is not constant, and is ob-
servable among adults also, it may be altogether disre-
garded. We are therefore warranted in concluding that the
temperature of the new-born animal, when placed near its
mother, is not superior to that of adults.
But if, at the temperature between 10° and 20° cent, or
50° and 68° Fahr., a new-born puppy be removed and kept
ON THE HEAT OF YOUNG ANIMALS. 69
an hour or two from its mother, its temperature falls con-
siderably, and continues falling until, in the course of three
or four hours, it stops a very few degrees above that of the
surrounding air.
This effect cannot be occasioned by the want of food for
so short a time ; and even though it were, the difference in
this respect between young and adult animals would be no
less remarkable. But the temperature begins to fall as
soon as the separation takes place, and the diminution is
not in the least retarded by furnishing the young animal
with milk from time to time. The same phenomenon takes
place with kittens and rabbits.
It might be supposed that this difference is accountable
from the difference in the natural coverings ; as rabbits, for
example, are born almost naked, and certainly cool more
rapidly than puppies and kittens, but, on the other hand :
these, although well covered with hair, will cool down to
the same degree, though more slowly, so that this circum-
stance can have but a secondary effect. Besides, the sub-
stitution of an artificial covering is found only to retard,
not to prevent the lowering of the temperature to the same
degree. We must therefore admit that, in the young animal,
less heat is produced in a given time than in the adult.
If we examine the change which the temperature under-
goes in the process of life, we shall find at first but little
alteration ; after a while the diminution will take place more
slowly; then the limit to its descent will be gradually higher
and higher in the scale, till, at the end of about a fortnight,
it will maintain itself at a degree nearly equal to that of
the adult animal.
This remarkable change which takes place in the young
of the mammalia, with respect to their temperature, makes
them pass from the state of cold-blooded to that of warm-
blooded animals-
70 ON THE HEAT OF YOUNG ANIMALS.
The phenomena above mentioned are not, however, com-
mon to the young of all the mammalia. The heat of young
guinea-pigs, born when the temperature of the air is between
10° and 20° cent, or 50° and 68° Fahr. in the above expe-
riments, will be found to be nearly as great as that of adults,
and if they be separated under the same circumstances, it
is not diminished. The same is true of many other ani-
mals of this class. The young of mammalia appear to be
distinguished into two groups in relation to animal heat.
Some are born, as it were, cold-blooded ; others warm-
blooded. Corresponding with this difference, is a distinc-
tion deducible from the state of the eyes. Some are born
with the eyes closed, others with the eyes open. The tem-
perature of the former, according to the foregoing experi-
ments, rises successively, and at the end of a fortnight,
(which is the period when the eyes open), it is nearly equal
to that of adults. Thus the state of the eyes, through hav-
ing no immediate connection with the production of heat,
may yet coincide with an internal structure influencing that
function, and certainly furnishes signs which serve to indi-
cate a remarkable change in this respect, since at the period
of the opening of their eyes, all young mammalia have
nearly the same temperature as adults.
Birds are known to have in general a temperature two or
three degrees above the mammalia. Wishing to know if this
was the case in the early period of life, I procured some
young sparrows about a week old. They were well fed and
collected in their nest. I took them out one by one and ex-
amined their temperature. It was between 35° and 36° cent,
or 98° and 100 Fahr. which is sensibly less than that of
adults. As their nest sheltered them, and they contributed
by mutual contact to keep each other warm, I separated
them, and although the air was mild (17° cent, or 62° 6'
Fahr.) they cooled rapidly. In an hour they fell from 36°
to 19° cent, or from 100° to 66° Fahr.
ON THE HEAT Ol YOUNG ANIMALS. 71
Another series of experiments was made when the air
was 22° cent. 71° 6' Fahr. Even at this high temperature
sparrows of the same age cooled rapidly to within one de-
gree of the atmospheric temperature. It is true that these
birds are hatched without feathers, but feathers are merely
a covering ; although they may retain, they cannot produce
heat. It is from within alone that animal heat can origi-
nate, however outward coverings may contribute to retard
its dissipation. Now, if it is true that birds produce heat
more than any other warm-blooded animals, the nakedness
of their bodies ought not to prevent them from maintaining
their temperature, especially when the external air is warm,
since man, and other mammalia with bare skins, have this
faculty. In a question so important as this, we should not
be satisfied with such reasoning, however probable, but en-
deavour to ascertain the truth by more direct experiments.
I stripped an adult sparrow of its feathers, cutting them
so as completely to expose its skin ; at the same time I
exposed to the air, then at the temperature of 18° cent, or
64° Fahr. young birds of the same species, taken from their
nest, where they had a suitable degree of warmth, which
the feathers that they had begun to acquire, tended to
preserve. Notwithstanding the advantage which this gave
them, they cooled down to within one or two degrees of
the external air, whilst the adult bird, though quite naked,
preserved the temperature which he had before the expe-
riment, being 20° cent, or 36° Fahr., above that of the at-
mosphere ; his internal source of heat, unaided by covering
or muscular exertion, being sufficient to counterbalance all
his losses.
Not to pass over any thing calculated to throw a doubt
on the conclusion which would naturally be drawn from
this experiment, viz. that the source of heat was less pow-
erful in the young than in the adult animal, we must take
72 ON THE HEAT OF YOUNG ANIMALS.
into account the circumstance of the smaller size of the
former. It is evident, that a small body, c&teris paribus,
will cool faster than a large one ; but in the case of its
producing heat, and of its developing it in sufficient quan-
tity, it will repair its loss, and retain its temperature,
whatever be its size. Now this is just the case of adult
warm-blooded animals. The greatest difference in their
size does not affect their temperature. The wren preserves
its warmth as well as the eagle, when the external temper-
ature is not at an extreme point. On the other hand, young
hawks, already covered with a thick down, and almost as
large as pigeons, in an atmosphere at 17° cent, or 62° 6'
Fahr. suffered a diminution of 14° or 15° cent, or 25° or
26° Fahr. All circumstances then unite in proving that
young birds produce less heat than adults. They require,
however, a degree of heat nearly equal to that of their
parents, and we have seen that not only the mild warmth
of spring, but the strong heat of summer is, of itself, in-
sufficient. This want is supplied by the shelter of their
nest, their mutual contact, and the assiduous care of their
parents, who are employed in imparting to them the
warmth of their own bodies during all the time that is not
occupied in obtaining food. These subsidiary aids become
less necessary with the growth of the young animals. Be-
fore they have acquired all their plumage, and when they
are still unable to take their food unassisted, they begin to
develope sufficient heat to maintain in spring and summer,
the degree which characterises warm-blooded animals.
The phenomena, indicated by the foregoing experiments
are not, however, common to all young birds. Some, as
soon as they are hatched, can maintain an elevated tem-
perature, if exposed to the air in a favourable reason. They
come into the world in a more advanced state than other
birds. When just hatched they can cat and run, and it is
ON THE HEAT OF YOUNG ANIMALS. 73
when other birds can perform these functions that they
also develope the same degree of heat.
The }roung birds which are able to run about and pre-
serve, their own temperature, are only convered with a to-
lerably thick down, and not with feathers, which is another
proof that the difference in the temperature of young ani-
mals and adults does not essentially depend on the cover-
ing with which their bodies are provided.
We have seen that the mammalia born with closed eyes,
and birds hatched without feathers, produce so little heat
as to be, in relation to the air, in the state of cold-blooded
animals. We have followed the changes which they un-
dergo as they advance in life, and have pointed out the
epoch at which they acquire the power of preserving a
high temperature when exposed without shelter to the
action of the air. Let us now examine the circumstances
in which they enjoy this faculty. They usually come into
the world in summer, when the external temperature is
favourable to them; — but suppose an alteration in this
respect, will young animals preserve their heat as well as
adults ? To solve this question, I obtained, in spring, a
winter-temperature, by immersing vessels in a mixture of
salt and ice. They were in all respects alike ; and the air
in these continued steady, at 4° c. or 39° F. In this cold
atmosphere I placed some young magpies, and left them
for a short time ; in twenty minutes one of them lost 14°c.
or 25°F. The others were examined at different intervals,
the longest not exceeding seventy minutes; they had
cooled 14°c. or 25°F. and 1 6°c. or 29°F. ; this was a con-
siderable and rapid loss of heat, which the animals could
scarcely survive. An adult of the same species, placed in
the same circumstances, sunk only 3° c. or 5° F., a loss not
incompatible with a state of health.
The cause of this difference must be looked for in the
74 ON THE HEAT OF YOUNG ANIMALS.
animals themselves, the external circumstances being the
same in both cases. By lengthening the duration of the
cooling process in the adult bird, I more than compensated
for the slight advantage which it might derive from its size
and feathers. We can scarcely ascribe the inequality in the
cooling of these birds to any other cause than a difference
in the power of producing heat. The blackbird, the jay,
the oriole, and the starling, were exposed to the same arti-
ficial cold, at an age at which their temperature had risen
and become stationary, with the same result as in the pre-
ceding case. The rapid progress which they make in ac-
quiring the power of producing heat is wonderful. But a
few days after the preceding experiment, the young birds
cooled much less when they were exposed to the same
degree of cold, although their appearance was very little,
if at all, altered. This influence of age is not confined to
birds ; I have proved its existence with the mammalia also.
Young guinea pigs at birth are able to walk and run, and
take the same food as their mother. They do not require
to be warmed by her, and appear to possess an equally
steady and constant temperature, when the season is not
severe ; but they have not the same power of maintaining
their temperature against cold. These points were proved
by means similar to those employed with birds, and it was
made equally evident that the difference depended on an
inferior power of producing heat.
On the whole, therefore, we are warranted in the general
conclusion, that the power of producing heat in warm-
blooded animals is at its minimum at birth, and increases
successively until adult age.
/o
CHAPTER II.
ON THE HEAT OF ADULT ANIMALS.
Among warm-blooded animals are to be found a small
number, which from their undergoing a considerable loss
of temperature, accompanied by a state of torpor during
the winter months, have been denominated hibernating
animals. The species which, in our climate, are universally
allowed to merit this appellation are, the bat, the hedge-
hog, the dormouse, the fat dormouse, the garden dormouse,
and the marmot. There are other species which some
naturalists suppose to be similarly circumstanced : of these
I shall speak hereafter. The, animals above-mentioned,
have all the characteristics of mammalia. They belong to
various genera and families, and are not distinguished from
other animals of the same class by any peculiarity of
structure. It is during their hibernation only that they
are in any manner to be distinguished from other mam-
malia. At this period they appear to be converted, for the
time, into cold-blooded animals; their temperature is
scarcely above that of the surrounding atmosphere ; they
are torpid like reptiles ; their respiratory movements are
irregular, feeble, and at long intervals; and, what is very
remarkable, this state continues several months, during
which they take no nourishment.
We can scarcely conceive two modes of existence more
dissimilar than the summer and winter lives of these ani-
76 ON THE HEAT 0*F ADULT ANIMALS.
mals. Does this depend, as some have supposed, on a
change of structure, which modifies their mode of being?
Or with the same organization at all seasons do they pre-
sent different phenomena, because their temperament is
subservient to changes in the atmosphere ?
If we consider that it is only when the temperature sinks
in autumn, that these animals retire into the holes in which
they are afterwards found, cold and torpid, we may pre-
sume that it is the operation of this cause which produces
the effect ; and after all that we have related above re-
specting the influence of external temperature on young
warm-blooded animals, we shall have little difficulty in
believing that it is so. If we suppose that in summer and
spring the hibernating mammalia produce less heat than
other adult warm-blooded animals, it is a necessary conse-
quence that their temperature should sink with the fall of
the year. It might however be supposed that deficiency of
nourishment produced these effects ; that not being able to
procure food in cold weather, their long fast threw them
into a state of langour approaching to death, and that
their coldness and insensibility, and their interrupted and
almost imperceptible respiration were the consequences.
Observation and experiment only can decide the question.
These animals have been made the objects of numerous
and important researches ; but they have been principally
examined during hibernation. Spallanzani, Hunter, Man-
gili, Prunelle, and De Saissy, have ascertained the pheno-
mena which they present during the state of torpor, the
means of recalling them to active life, and of again inducing
torpidity, as well as several other facts connected with
them. Of the numerous remarkable phenomena presented
by the hibernating mammalia, those only need arrest our
attention which relate to their temperature, since they
belong to the subject with which we are now engaged.
ON THE HEAT OF ADULT ANIMALS. 77
They are the more interesting because they seem to in-
fluence all the other phenomena. Buffon thought that
the temperature proper to the hibernating mammalia was
10° of Reaumur's thermometer, which is equal to 12° 5'
cent, or 54° 5' Fahr. but the physiologists just mentioned
have proved that it is from 35° cent, or 93° Fahr. to 37° cent,
or 98° 6' Fahr. in spring and summer. Here then they do
not essentially differ from other adult mammalia ; but if we
wish to discover whether, notwithstanding this similarity of
temperature, they really produce less heat, we must see
how they bear the influence of natural or artificial cold.
M. de Saissy has repeatedly examined these animals at
different periods during their state of activity. On the
sixth of August, the temperature of the air being 22° cent,
or 73° Fahr. that of a marmot was 36° 5' cent, or almost
98° Fahr. in the axilla. On the twenty-third of September,
the air was 18° cent, or 64° 5' Fahr. and the marmot 31°
25' cent, or 88° Fahr. and on the tenth of November, the
air was 7° cent, .or 44° 6' Fahr. and the animal only 27°
25' cent, or 81° Fahr. which is 9° 25' cent, or 16° 6' Fahr.
lower than its temperature in the month of August. A
garden dormouse examined under the same circumstances
had a warmth of 36° 5' cent, or 88 Fahr. on the third of
August; of 31° cent, or 87° Fahr. on the twenty-third of
September ; and only 21° cent, or 69° 8' Fahr. on the tenth
of November, having lost 15° 5' cent, or almost 28° Fahr.
since the first examination. The examination of a hedo-e-
hog gave the following results. It was 37° cent, or 99°
Fahr. on the third of August ; 35° cent, or 96° Fahr. in
September ; and only 13° 75' cent, or 57° Fahr. having
lost more than 20° cent, or 40° Fahr.
The author of these observations has not informed us
whether these animals were in the constant practice of
taking food whilst undergoing this loss of temperature, a
78 ON THE HEAT OF ADULT ANIMALS.
circumstance of some importance, to enable us to judge
of its cause, and to draw a strict comparison between the
hibernating and other mammalia.
M. de Saissy succeeded in torpifying a marmot in the
months of May and June. He had inclosed it with a little
straw in a copper box, the lid of which was pierced with a
hole about half an inch in diameter. After leaving it in an ice-
house for twenty-four hours, he exposed it to an artificial
cold of 10°c. or 18°F. below the freezing point. It fell into a
profound torpor eleven hours after, and although its tempera-
ture had fallen from 35°c. or 95°F. to 5°c. or 4l°F. ; yet its
health did not appear more altered than in the ordinary
circumstances of hibernation ; for, on being afterwards
exposed to the warmth of the atmosphere, it recovered
from its torpor, and resumed its wonted activity.
This interesting; fact shews that hibernating- animals
may become torpid at any season, and from other causes
than the want of nourishment ; and also that the pheno-
mena which take place in hibernation do not proceed from
any change in the organization of the animal at the end of
summer, as some have supposed. We may now compare
the hibernating with the other mammalia, with reference
to the external temperature during spring and summer,
when both are in the enjoyment of the full activity and
vigour of life.
In the preceding experiment, the degree and duration of
the cold to which the marmot was subjected, were such as
might lead us to question whether non-hibernating animals
would not have lost as much heat under the same circum-
stances, enclosed in a box with so small an aperture, that
respiration might have been impeded. We may also con-
clude, from the following observation of the same author,
that cold was not the only influential cause : — " The mar-
mot which I reduced to a torpid state at two different
ON THE HEAT OF ADULT ANIMALS, 79
times, only became so, I believe, in consequence of its oc-
curring to me, to close the aperture in the lid at a time
when its respiration was much enfeebled. It was only in
this manner that I succeeded, for all my previous attempts
had been vain." We have here, then, a combination of
two causes — external cold, and diminished respiration ;
without being able to distinguish the respective effects of
each.
I performed the following experiment, with a view to
determine the influence of cold upon an hibernating animal,
compared with other warm-blooded animals in similar cir-
cumstances. In April, 1819. the air being 16°c. or 61°F.
an adult bat, of the long-eared species, recently taken, in
good condition, and at the temperature 34°c. or 93°F. was
placed in an earthen vessel, which was cooled by a mixture
of ice and salt, which surrounded it, till the air within
was reduced to l°c. or 33° 8' F. It had a cover, which
allowed a free communication with the external air. After
the animal had been there for an hour, its temperature was
reduced to 14°c. or 57°F., being a loss in this short space
of time of 20c. or 36°F. Guinea pigs, and adult birds,
placed in 4;he same circumstances, lost, at the utmost, no
more than two or three degrees, although the influence of
the cold was prolonged in this case, to compensate for the
difference of size. We see from this, that bats are in the
habit of producing less heat than animals which do not
hibernate ; and it is to this cause that we must chiefly
ascribe the reduction of their temperature during the cold
season. If we compare this experiment on the bat, with
those on young warm-blooded animals, we perceive a
remarkable analogy, with this difference, however, that
what is a transitory condition in the young of most warm-
blooded animals, is permanent in the bat.
We may safely extend the result of this experiment to
80 ON THE HEAT OF ADULT ANIMALS.
the whole group of hibernating animals, — and draw this
general conclusion respecting them, that whatever causes
of a different nature may influence their temperature
during hibernation, it is mainly to be attributed to a defi-
ciency in the power of producing heat.
81
CHAPTER III.
THE INFLUENCE OF THE SEASONS IN THE PRODUC-
TION OF HEAT.
Age, the influence of which we have just been considering,
is certainly not the only cause common to warm-blooded
animals which modifies the development of heat. We
shall now examine the effect of the seasons in this respect.
From reflecting on the remarkable change produced in
the vertebrated cold-blooded animals, by the long-continued
action of heat and cold, which has progressively modified
their constitution, so that in summer and in winter, though
placed, in other respects, in precisely the same circum-
stances, they have a vitality so different that they would
scarcely be known as the same beings, except from ob-
serving their form and structure ; I was led to presume
that the other classes of the vertebrata, though more ele-
vated in the scale of beings, might also experience some
constitutional change under the constant action of causes
so powerful.
As no inquiries appeared to have been instituted on this
subject, I was induced to take it up, and I did so the more
willingly, as it is obviously connected with the influence
of climates.
I proposed to examine whether, in the opposite seasons
of winter and summer, warm-blooded animals, not hiber-
nating, present any difference in respect of their power of
82 THE INFLUENCE OF THE SEASONS
producing heat. This was to be ascertained by placing
animals of the same species in the same conditions of
refrigeration in winter and in summer, and observing if
their temperature diminished unequally. In this case it
would follow, that their power of producing heat is not the
same at these two periods, supposing nothing to be omitted
to render the experiments parallel.
It is necessary, in the first place, that the animals se-
lected should be as similar as possible, and that the expe-
riments should be sufficiently numerous to obviate any
considerable influence from individual diversities. In
order that the mode of refrigeration should be the same,
attention must be paid, not only to the temperature, but to
the humidity of the atmosphere; for a difference in the
hygrometric state of the air would produce a corresponding
difference in the evaporation from the lungs and skin, and
consequently in the quantity of heat lost.
The apparatus consisted of glass vessels, of the capacity
of two pints, placed in a freezing mixture of salt and ice.
The air thus cooled, is at its point of saturation with mois-
ture. When it is at zero cent, or 32° Fahr. the animal is
introduced, and placed on a false bottom of gauze, to pre-
vent the contact of the cold glass. A lid covered with ice is
placed over the vessel, but so as to permit change of air
for the free exercise of respiration ; and, in order more
effectually to secure the purity of the air, a concentrated
solution of caustic potass is placed at the bottom, to absorb
the carbonic acid, which it readily does, through the gauze.
The general results are as follows : —
In the month of February the experiment was made, at
the same time, upon five adult sparrows. In the course
of an hour they lost, on an average, only 4° cent, or 72°
Fahr. — some having lost none, others only 1° cent, or 1° 8'
Fahr. Their temperature then remained stationary, until
ON THE PRODUCTION OF HEAT. 83
the end of the experiment, which lasted three hours. In
July, I tried the same experiment on four others. Their
temperature, in the course of the first hour, sustained an
average loss of 3° 62' cent, or 6° 5' Fahr. j at the end of
the third hour the average reduction from their original
temperature was 6° cent, or 10° Fahr. In another series of
experiments on six sparrows, in the month of August, the
mean loss of temperature at the end of the first hour was
1° 62' cent, or 2° 9' Fahr. ; and after three hours, 4s 87'
cent, or 8° 76' Fahr.
These experiments indicate a considerable change ef-
fected in the constitution of these warm-blooded animals,
by the influence of the seasons ; they shew that the con-
tinued elevation of temperature diminishes the power of
producing heat, and that the opposite state of the atmo-
sphere, provided the cold is not too severe, increases it.
g 2
84
CHAPTER IV.
ON ASPHYXIA.
Having examined the principal points connected with the
influence of heat on the animal economy, we shall now
pass to the consideration of the air, another physical agent
no less important in its relation to life.
The ancients were to a great degree, ignorant of the pro-
perties of the atmosphere, and most of them have only been
ascertained of late years. Whilst they remained unknown,
it was impossible to understand the action of the air upon
the animal economy. Already our knowledge of this agent
has been advantageously applied : the subject, however, ad-
mits of being carried considerably further, but the investi-
gation requires much time.
The earliest knowledge which was acquired respecting the
relations of the air with the animal economy, was the most
important fact of the necessity of this fluid for the support
of life, a necessity so urgent, that man, and the animals
which most resemble him in their structure, perish almost
as soon as they are deprived of it. Three or four minutes
suffice to do away with all appearance of sensation and
motion, and though some feeble remains may yet exist in
the interior of the body, these are quickly extinguished.
The cessation of external sensation and motion is called
apparent death, and in this case it is scarcely short of actual
death. So powerfully docs the privation of air tend to destroy
ASPHYXIA. 60
life, that animals of the largest size, and those possessed of
the greatest muscular energy, sink under it almost as quickly
as the smallest and the weakest. We might be inclined
suppose that those warm-blooded animals, which are con-
stantly obliged to plunge under water in pursuit of prey, or
to elude their enemies, would acquire the power of resisting
the effects of the privation of air longer than other animals.
To ascertain this fact, a moor-hen was plunged in water :
at the end of about three minutes, it had neither sense nor
motion. Some birds, it is true, perish sooner, and others
perhaps, will survive longer ; but this fact indicates of
what slight avail on this occasion is habit, which, in general
has so powerful an influence on the animal economy.
The hope of producing such an alteration in animals as
to enable them to support the privation of air, for a much
longer term than is natural to them, led BufFon to a very
important discovery with respect to young animals. He
placed a greyhound bitch of the largest species, when on
the point of giving birth to young in a tub of warm water,
and secured her in such a manner that she was obliged to
bring them forth under water. These were afterwards for
the sake of nourishment transferred to a smaller tub of
warm milk, but without giving them time to breathe. They
remained there for above half an hour, after which they
were taken out and all found alive. They began to breathe,
which they were allowed to do for half an hour, and were
then again plunged in the milk which had been warmed
again in the mean time. There they remained for another
half hour, and when they were again taken out, two were
quite strong, and seemed not to have at all suffered: The
third appeared drooping: but was carried to its mother,
and soon recovered. The experiment was continued on
the other two, they were allowed to breathe a second time
for about an hour ; and were then plunged once more in
86 ASPHYXIA.
the warm milk for half an hour, after which they appeared
as strong as before. However, being taken to their mother
one of them died the same day, whether by accident or
from having suffered from the privation of air could not be
ascertained. The other lived as well as the first, and both
thrived as well as the other puppies produced after the
bitch was removed from the water, and which had not
undergone the ordeal.
Le Gallois who does not appear to have been aware of
what Buffon had done, made experiments upon rabbits
with the same view. He undertook them, for the purpose
of ascertaining how long a full grown foetus could survive
without breathing, when separated from its communica-
tion with the mother. He found that when he deprived
them of respiration by immersing them in water, the mean
duration of their life was twenty-eight minutes. But this
power of resisting the want of air, rapidly diminishes with
the progress of life. Le Gallois observed, that at the end of
five days, young rabbits plunged in water, live only sixteen
minutes. At the end of another five days, the time is re-
duced to five minutes and a half, and when they are fifteen
days old, they have then reached the limit which adult
warm-blooded animals can rarely pass, when they are with-
drawn from the influence of the air. The results of these
experiments would favour the belief, that the duration of
the life of new-born mammalia, under such circumstances,
is about half an hour. I was much surprised, however to
find that the guinea-pig, at birth, when plunged in water,
lives only three or four minutes longer than the adult. I
found other species also in which the difference was not
greater. I therefore directed my attention to discover the
cause of this remarkable difference.
My researches upon cold-blooded animals had enabled
me to perceive the g;rcat influence of temperature over this
ASPHYXIA. 87
mode of existence. Having afterwards found that warm-
blooded animals present among themselves marked diffe-
rences in the production of heat, I concluded that these
might give rise to modifications of their system, analogous
to those produced by external temperature upon cold-
blooded animals.
Let us then compare together the species which have
been just mentioned, in this point of view. On the one
hand, new-born dogs, cats, and rabbits are similarly af-
fected in asphyxia. They all give signs of life for half an
hour, and sometimes longer : now these are the very species
in which we have observed so feeble a production of heat.
We formerly observed, that in this respect they bore a close
resemblance to reptiles and fishes ; we see here that they
also resemble them in the power of sustaining the priva-
tion of the air, which implies an intimate connection be-
tween these two phenomena. On the other hand guinea-pigs
are in the class of those which produce most heat at birth ;
and of these I have never seen one which lived above seven
minutes under water, and frequently they do not attain
even that limit.
We shall be better enabled to perceive the cormexion
between animal heat and this mode of vitality, by observ-
ing their respective modifications in the progress of early
life.
We have seen, in the experiments of Le Gallois, that at
the end of the fifth day the duration of life during as-
phyxia is reduced one-half: now this reduction corresponds
to a sensible elevation of their temperature. The same is
the case after the second interval of five days; the heat is
then much increased, and the power of living without
respiration is considerably diminished. Lastly, when they
have arrived at the fifteenth day, a period when they
usually have a temperature nearly equal to that of adults,
88 ASPHYXIA.
they scarcely differ from them in the duration of asphyxia.
If, instead of passing at once from the first to the fifth
day, we examine the young animals in the intervening days,
we shall find, that during the first and second, and even,
not unfrequently, the third, the duration of asphyxia is
only very slightly altered. The production of heat cor-
responds with this, and both phcenomena likewise concur
in the more rapid and striking change that quickly after
takes place.
We see that the distinction formerly pointed out between
young mammalia, founded in the production of heat, is
applicable to them also in respect to the duration of life
when deprived of respiration. This duration has its maxi-
mum in the group of mammalia which produce the least
heat at birth, and its minimum in those which produce the
most.
I have made similar researches respecting birds. I have
exposed young sparrows separately to the action of the air
to compare their rate of cooling. The temperature of the
atmosphere was at 16° cent, or 61° Fahr. in the month of
May. One of them, which had, in half an hour, cooled
from 35° cent, to 19° cent, or 95° to 66° Fahr. was after-
wards warmed, and when he had regained his original heat
was immersed in water ; he lived in it eight minutes ; now
adults live only a minute and a few seconds. The other,
whose temperature was only reduced to 26° cent, or 79°
Fahr. was in like manner warmed again and immersed
in water ; he gave signs of life for only four minutes.
Others, which lost little heat by exposure to the air, dif-
fered equally little from adults in the duration of life
under water.
These facts are sufficient to shew the correspondence
between animal heat and the power of living, excluded
from the contact of the air ; but there is a limit at which
ASPHYXIA. 89
this correspondence ceases, and animals soon arrive at it.
The increments of heat taking place beyond this limit have
no longer any sensible influence upon the duration of life
in asphyxia.
Sect. 1. — hiftuence of external Temperature.
In the preceding experiments no notice is taken of
the temperature of the water in which the submersion
took place. This circumstance has a powerful influence
on the cold-blooded vertebrata. Is it the same with the
warm-blooded ?
We shall examine the effects of temperature between
0° and 40° cent., including the range the most nearly related
to the animal economy.
I subjected some kittens a day or two old to compara-
tive experiments. In water cooled to 0° cent, or 32° Fahr.
they ceased to give signs of sensibility and motion, after
four minutes and thirty-three seconds, taking the mean
of nine experiments. At a temperature of 10° cent, or
50° Fahr. the duration of life extended to ten minutes and
twenty-three seconds. At 20° cent, or 68° Fahr. it in-
creased considerably, being on an average thirty-eight
minutes and forty-five seconds ; at 30° cent, or 86° Fahr.
a retrograde course commenced, as they lived but twenty-
nine minutes ; lastly at 40° cent, or 104° Fahr. they lived
ten minutes and twenty-seven seconds.
It may be remarked, in the first place, that the degree
most favourable to life, in the circumstances in which the
kittens were placed, may, with reason, be considered as a
cold temperature. A bath at this degree, commonly pro-
duces upon our bodies a very lively sensation of cold ; and
is 20° cent, or 36° Fahr. below the mean temperature of
warm-blooded animals. The change of the external tem-
perature either above or below this degree, produces dele-
90 ASPHYXIA.
terious effects, but in different proportions. A rise from
20° cent, or 68° Fahr. to 40° cent, or 104° Fahr. is neces-
sary to produce the same effect as a fall from 20° to 10°
cent, or 68° to 50° Fahr. ; similar experiments upon pup-
pies, &c. of the same age lead to the same results. This
influence of external temperature is not confined to early
age, it extends to every period of life ; and although the
life of adult mammalia (and, yet more, that of birds) is so
closely connected with the influence of the atmosphere,
that when it is suspended death takes place so soon as to
afford but a very limited field for observation, the fact is,
notwithstanding, apparent.
There are, then, two principal conditions which influence
the life of warm-blooded animals when deprived of air.
The one is the quantity of heat developed by the animals
themselves, the other is the external temperature to which
they are exposed.
91
CHAPTER V.
ON RESPIRATION IN YOUTH AND ADULT AGE.
After having observed what circumstances modify the
duration of life, when animals are deprived of air, let us
now examine the influence of this fluid upon the body.
Air, in contact exteriorly with the skin, and interiorly with
the lungs, exerts its vivifying influence much more power-
fully on the latter than on the former. As soon as air is
intercepted from the lungs of warm-blooded animals, al-
though the whole external surface be still exposed to it,
they experience the same distress, as if they were entirely
plunged in water; and if this interception of the air be
continued, asphyxia is produced as quickly as by submer-
sion. If, on the contrary, the contact of air with the skin
is prevented, whilst it has free access to the lungs, no in-
convenience is found to arise from it.
These facts have necessarily led to the lungs being re-
garded as the only organ intended to support life by means
of contact with the atmosphere. We will, for the present
admit the correctness of this opinion, and shall, in the first
place, consider the mutual relation of the lungs and air for
the support of life ; we shall afterwards examine if the
skin does not contribute to the same effect.
The first relation of the air to the lungs, depends on the
capacity of these organs, and the extent of surface which
they present. The differenee in the size of warm-blooded
92 RESPIRATION IN YOUTH AND ADULT AGE.
animals, indicates a corresponding difference in the capa-
city of their lungs. But when we limit the respiration of
animals of various sizes to the air contained in the lungs
by placing a ligature upon the trachea, the small live al-
most as long as the large. One might hence infer that the
extent of surface of the lungs in animals of the same class
is also proportioned to their size. We shall return to this
subject.
The air which supports life must be continually renewed.
The necessity of this renewal is proved by the accidents
which happen when it is suspended. The whole of the
air in the lungs is not, however, renewed by an inspiration
and expiration ; and it is the portion of air which enters
and issues from the lungs when these acts are performed,
which essentially contributes to the support of life.
Although the will has a slight control over the respi-
ratory motions, yet, on the whole, they may be considered
as involuntary ; and in a state of health, and in a condition
free from the influence of disturbing causes, they have a
strong tendency to uniformity.
The capacity of the lungs, as compared to the size of
the trunk, is but little affected by age. If it is rather less
in youth than in adult age, the succession of respiratory
movements is, in general, more rapid, so that, in the same
space of time, the quantity of air which comes in contact
with the pulmonary surface of a young animal is propor-
tionally equal, if not superior, to that which is inspired by
an adult.
From the necessity of the renewal of the air in respiration,
it may be inferred that it undergoes some change. In two
respects this change is evident. The expired portion has
acquired an increase of temperature, and is charged with
vapor.
It is, however, an ascertained fact, that the most im-
RESPIRATION TN YOUTH AND ADULT AGE. 93
portant alteration of the air during respiration is chemical,
and consists principally in the substitution of carbonic
acid for a part of its oxygen. When the quantity of air
in which a warm-blooded animal respires, is limited, this
alteration is progressive, and when it arives at a certain
point, the animal dies as it does when altogether deprived
of the contact of the air. All warm-blooded animals,
when thus confined to a limited quantity of air, alter it to
nearly the same degree, and though it still contains a
small quantity of oxygen, it is as fatal to them, when
placed in it, as submersion in water. The space of time
which they live in a given quantity of air, is determined
by the rapidity with which they consume the quantity of
oxygen, which is susceptible of alteration by respiration.
This subject merits particular attention. The difference
between individuals in this respect does not wholly depend
on the proportionate quantity of air admitted into the
lungs, but in part on the constitution of the animals. I
placed some sparrows, in every respect as much alike as
possible, in vessels of the same form, and containing each
a litre, or about a pint and three quarters of air, inverted
over mercury. Still further to ensure equality in the con-
dition of the experiments, I performed them simultane-
ously, thereby avoiding differences in the temperature, pres-
sure and humidity of the air. In a great number of ex-
periments, I ascertained that there was sometimes a con-
siderable difference in the duration of life with the same
quantity of air, and that the shortest and the longest du-
ration might differ by one-third. The air, however, was
altered nearly to the same degree by all, so that the du-
ration of life was principally affected by the comparative
rapidity in the consumption of oxygen.
Since the experiment was complicated by the presence
of carbonic acid ; to the action of this gas, varying accord-
94 RESPIRATION IN YOUTH AND ADULT AGE.
ing to the sensibility of the individuals, might perhaps be
attributed a difference in the respiratory movements, which
would affect the rapidity with which they consumed the
air, and thus diminish the respective duration of their lives.
The presence of carbonic acid does, it is true, influence the
respiratory movements, but the differences above stated,
equally existed when I employed means to absorb the car-
bonic acid as it was formed. We must then admit other
causes depending upon individual constitution which affect
the rapidity with which the air is consumed.
We shall now proceed to consider the changes in this
respect, which the same individual undergoes in the pro-
gress of life. In youth, all the functions seem to conspire
to promote the development and growth of the body. Di-
gestion is more rapid — the calls of appetite are more fre-
quent and more pressing — respiration is more rapid, and
when we consider the necessity of air for the continuance
of life, we might be induced to presume, that the relative
consumption of air was greatest in youth. Our reasoning
may be deceptive ; experiment alone can decide the point.
In this investigation there are several precautions neces-
sary to arrive at accurate praetical results. We must avoid
comparing those animals in which age occasions a great
difference in size, as the question is to determine the
influence derived from the constitution, and not from a
difference in bulk. But as the increase of the body and
the changes in the constitution are inseparable during a
certain period of life, we ought to choose those species
whose dimensions vary the least in the progress of life,
and in which the other differences are more prominent.
The species used in the preceding experiments combines
these advantages. To simplify the comparison still more?
we must absorb the carbonic acid as it is formed.
The experiment was made with vessels containing a
RESPIRATION IN YOUTH AND ADULT AGE. 95
pint and three quarters or sixty-one cubic inches of air,
inverted over a solution of caustic potash. The animal was
placed on a partition of gauze. The young sparrows
which I employed were apparently from eight to ten days
old : their bulk was about two cubic inches and a fifth,
and that of the adults rather more than twice as much.
This difference in size alone would occasion a more rapid
consumption of air by the older birds, and it ought not to
appear extraordinary that they died sooner. The mean
duration of their life was 1 h. 30' 32" ; but the young
sparrows prolonged their existence to so disproportionate
an extent as to astonish me; their mean term was 14 h.
49' 40".
Towards the close of the experiment, when they have
altered the air until it is no longer capable of supporting
life, we may suppose that they still live as long as they
can when deprived of air. We have seen in the former
chapter upon asphyxia, that this period is longer in young
than in adult animals. But the maximum with sparrows
is seven minutes. It is evident, therefore, that in allowing
for all these differences, the young sparrows lived much
the longest in the same quantity of air, and that conse-
quently their consumption of it is comparatively less.
What is the modification of the animal economy, de-
pendant upon age, which corresponds with this difference
in the consumption of air ? The most striking difference
between the constitution of young animals and that of
adults exists, as we have already shewn, in their production
of heat. It is in the early steps of life that warm-blooded
animals develop least heat. It is also in the early stages of
life that the. sparrows consumed the air most slowly.
In order to verify this relation under circumstances the
most favourable to a satisfactory result, these experiments
were continued on the same snecies at less distant ages.
96 RESPIRATION IN YOUTH AND ADULT AGE.
Their growth is so rapid that they scarcely begin to feed
themselves before their size is nearly equal to that of
adults. Their temperature then supports itself in the open
air. It was at this age that I compared them with adults.
Five of these young animals, placed in sixty-one cubic
inches of air, and supported by a gauze partition over a
strong solution of caustic potass, lived, on an average
2h. 39', but adults, in the same circumstances, lived only
lh. 32'. Here we have no correction to make either for
volume, or for difference in the duration of life after the
air has become unfit for respiration. These are alike in
both these respects, or differ too slightly to deserve atten-
tion ; but they differ essentially in the production of heat,
and we see that the young birds, which produce much less
heat, also consume air more slowly than adults.
These researches, following a different method, were
extended to mammalia, I placed over mercury, in ves-
sels containing the same quantity of air as in the pre-
ceding experiment, puppies a day or two old, and Guinea
pigs about a fortnight old. The dogs were taken out
at the end of four hours and fifty-nine minutes, and
the Guinea pigs after an hour and forty-two minutes.
By analysis of the air, the mean of the quantities of
oxygen was found to be sensibly the same. Regarding
only the difference of bulk, the consumption of air by
the puppies ought to have been much more rapid, be-
cause they were larger, but when we recollect the fact pre-
viously established that young puppies at birth produce
much less heat than Guinea pigs, we see here the same
relation to exist between the consumption of air, and the
production of heat, that we had determined in the case of
the sparrows.
These facts regarding the vital heat and respiration of
young animals compared with adults, opposed, as they are,
RESPIRATION IN YOUTH AND ADULT AGE. 97
to preconceived and general opinion will, on reflection, be
seen to be in perfect accordance with the order of nature.
Is it not the same relation which the cold-blooded have
long been known to bear to the warm-blooded vertebrated
animals, and does not the same relation exist between the
mammalia and birds ?
98
CHAPTER VI.
ON THE INFLUENCE OF THE SEASONS UPON
RESPIRATION.
In the course of trie seasons, several changes in the atmo-
sphere occur, which may affect respiration. Such are
variations in the temperature, pressure and density of the
air.
Let us consider the effects of different degrees of density
of the air upon the consumption of this fluid in respiration,
independently of other atmospheric changes. We know
that we can quickly destroy warm-blooded animals placed
under the receiver of an air-pump, by rarefying the air
which they breathe. It is true, the rarefaction of the air
does not produce one effect only; but whatever other
effects it may produce, we can attribute the suddenness of
the death only to the fact, that air when dilated is consumed
so slowly as not to suffice for the maintenance of life.*
From this condition, which we shall consider as simple,
we shall proceed to another which is complicated. When
the temperature of the air changes, its density changes
also ; cold contracts it, heat dilates it. We have noticed
the effects of the change of density, but what is the pecu-
liar effect of temperature ? We here leave out of view its
influence on the motions of respiration and those of the
heart, as this exists in extreme cases only. The air being
* See Legallois' Papers on Respiration.
INFLUENCE OF THE SEASONS, &C. 99
rarer in summer and at the same time warmer, but to a de-
gree which does not affect the motions of the respiratory
muscles or of the heart, what is the effect of this elevation
of temperature? Does it act conjointly with the rarefac-
tion in diminishing the consumption of the air, or does it
counteract such an effect ? The respective effects of ele-
vation of temperature and rarefaction of the air do not ap-
pear to have been ever examined. Their combined opera-
tion has not been altogether neglected. Crawford made
guinea-pigs breathe in air of different temperatures, and
found by analysis that more carbonic acid was produced in
air at the temperature of 8° cent, or 46 Fahr., which may be
considered as cold, than in warm air of nearly 35° cent, or
95 Fahr. : but as the colder is likewise the denser air, this
latter circumstance may have occasioned the difference no-
ticed by Crawford. Analogous experiments performed by
Delaroche, obtained variable and somewhat contradictory
results. The subject must therefore be considered as un-
decided, and I shall not enter upon it here, as it requires
the employment of means which I have reserved for ano-
ther occasion. I have devoted considerable attention to it,
and I shall state the facts which I have proved, when I
come to speak expressly of the changes effected in the air
by respiration.
But another important question remains : Does the
change of seasons occasion modifications in the constitu-
tion, such, that, supposing the density, temperature, &c. to
remain the same, it would be consumed in different propor-
tions at different periods ?
The facts which we have already established lead us
to form a very probable conjecture as to the result of the
inquiry. In following the changes which take place with
the progress of age in warm-blooded animals, we have
seen, that at different periods from birth to maturity, the
h 2
100 THE INFLUENCE OF THE SEASONS
consumption of air increases, ceteris paribus, with the deve-
lopment of heat. This connexion between respiration and
the production of heat, is in accordance with the relation
which we have observed that animals of different classes
bear to each other, such as the cold-blooded to the warm-
blooded vertebrata, and the mammalia to birds. We may
therefore expect likewise to discover a corresponding rela-
tion in cases like that which we are now to examine, in
which it may not as yet have been observed.
It has been shewn in one of the preceding chapters, that
warm-blooded animals, if in full vigor, and possessed of
constitutions adapted to the climate, possess the power of
producing heat to a greater degree in winter than in sum-
mer. There ought, then, circumstances being in other re-
spects the same, to be a greater consumption of air in win-
ter than in summer, if there really exist an intimate con-
nexion between the two functions.
With a view to determine this question, I made in Ja-
nuary, 1819, a series of experiments on six yellow-hammers,
( Emberiza citrinella,) in separate receivers, each containing
71 cubic inches, or rather more than two pints of air, placed
over mercury, with a gauze partition for the bird to rest on.
I raised the temperature of the air to 20° and 21° cent, or
68° and 70° Fahr. in order to represent a moderate summer
temperature. The average of the duration of their life in this
quantity of air was lh. 2' 25". In August and September
the same experiments were repeated at the same tempera-
ture, upon 13 individuals of the same kind. The average
duration of their life was then lh. 22'.
In January of the same year, the same experiment was
performed on four green-finches; (Loxia chloris.) They
lived on an average lh. 9' 15". In August, for want of
opportunity to procure a larger number, the experiment
was tried upon only two ; one lived lh. 30', and the other
UPON RESPIRATION. 101
lh. 36'. This is mentioned merely, as tending to confirm
the preceding ; alone, the fact would be altogether insuffi-
cient.
The experiments, hitherto, had been made over mercury ;
consequently, the carbonic acid formed during respiration
remained in the receiver, and complicated the experiment.
I proposed, in another series of comparative experiments
in the two seasons, to suppress this cause of complication,
by placing the receivers over a strong solution of caustic
potass, capable of absorbing the carbonic acid gas which
was produced.
With this modification, I resolved to apply it to a great
number of individuals. At the close of December and in
January, it was tried upon 16 yellow-hammers. The mean
duration of their life was lh. 7' 37". The following sum-
mer, at the close of August and beginning of September,
the temperature being at 20° cent, or 68 Fahr., and 21°
cent, or 70 Fahr. ; the same experiment was made upon
12 yellow-hammers ; — they lived on an average lh. 23' 43"
The concurrent evidence of these varied experiments leaves
no doubt as to a change being produced in the constitu-
tion of the animals by the influence of the seasons.
I considered that the phenomena presented by animals
respiring the same quantity of air, would likewise furnish
some data calculated to throw light on the mode in which
they consume air in the different seasons.
When respiration is performed in a limited portion of
air, that fluid loses its oxygen and receives an accession of
carbonic acid. When this last is absorbed as it is formed,
the diminution of the oxygen will still occasion the respi-
ration to be oppressed. An unequivocal symptom of this
oppressed respiration in birds is the opening of the beak,
a symptom which is manifested sooner or later, according
to the more or less rapid consumption of the oxygen.
102 THE INFLUENCE OF THE SEASONS.
I noted in January, in the case of 10 yellow-hammers,
the period at which they began to open their beaks, during
an experiment similar to that above described, the carbo-
nic acid being absorbed by a solution of potass. The aver-
age period was 52' 53" from the commencement of the
experiment. Similar observations made at the end of Au-
gust and beginning of September, upon 12 yellow-ham-
mers, in the same circumstances furnished an average of
lh. 8' 55" from the beginning of the experiment. There
could not be a more evident confirmation of the conclusion
to which the former experiments likewise tended, that the
consumption of oxygen is more rapid in winter than in
summer.
In order to obviate any objection which would attribute
the result to a diminished quantity of air in the winter ex-
periment, it may be mentioned, that the mean pressure
was the same in both seasons ; but the air with which the
vessels were filled was colder previously to raising it to the
summer temperature, so that there was really more air
used in the winter experiment.
Hence, we mav conclude, that the differences in the
phenomena of respiration depended on the change in the
constitution, effected by the influence of the seasons. Such
a conclusion might have been anticipated from the fact
proved by former experiments, that the power of producing
heat in warm-blooded animals is greater in winter than in
summer, and from the evident relation subsisting between
the consumption of air and the development of animal
heat.
103
CHAP. VII.
ON PERSPIRATION, OR EXHALATION,
When on the subject of cold-blooded animals, we fully-
treated the influence of different states of the atmosphere
in increasing or diminishing the loss of weight occasioned
by perspiration in that class of animals. We shall now
resume the same series of researches, with respect to the
perspiration of warm-blooded animals.
Sect. 1. — Loss by Perspiration in equal and successive
periods.
We shall begin by determining what is the proportion
between the successive quantities lost in equal times under
the same external influence.
Four young guinea-pigs were placed separately in small
iron-wire cages. The temperature of the room was 14°
cent. 57° Fahr., and the air was kept still, and free from
draughts. They had been previously fed, that they might
be in the best condition. They were weighed from hour to
hour. A plate was placed under the cage to receive their
urinary and alvine evacuations. Every excretion was
weighed immediately, and the liquid part taken up with
silver paper, the weight of which was determined both
before and after the operation. The experiment lasted six
104 ON PERSPIRATION, OR EXHALATION.
hours. The quantities lost, compared from hour to hour,
were so various, that no tendeney to a regular course could
be recognized. But on comparing them at intervals of two
hours, the losses decreased successively in some, and a
tendency to the same result was manifest in the others ;
again, in comparing them at intervals of three hours, the
diminution of the losses effected in three equal periods
were evident in all,
A similar experiment was tried upon another genus of
mammalia. Four adult mice were placed in small wire
cages, with the same precautions regarding the excretions.
The temperature of the room was 19° cent, or 66° Fahr.
The experiment was continued for six hours ; it was at-
tended with the same results as that upon the guinea-pigs.
Instead of pursuing these researches upon mammalia,
I thought it preferable to take animals in the other class of
warm-blooded vertebrata. The more the organization dif-
fers in individuals which present the same phenomena,
the more certain it is that these phenomena are common to
a greater number of species.
These experiments were therefore repeated upon birds.
Four sparrows were exposed to the air in a room, at 19°
cent. 66° Fahr. ; four others to a temperature of 20° cent.
68° Fahr., employing the same methods, and the same pre-
cautions, and for the same space of time as in the foregoing
experiments, and obtained the most complete confirmation
of the former results. It did not seem expedient to prolong
the duration of the experiment, lest the powers of the ani-
mals should be reduced by too long abstinence.
By stopping short at the irregularities which are observ-
able in successive intervals of a single hour, we might be
deceived as to the progress of perspiration, and not discover
any certain tendency, and the fact might be united to
many other anomalies in vital phenomena in support of the
ON PERSPIRATION, OR EXHALATION. 105
opinion, that they are not susceptible of being reduced to
laws. They may, however, be so examined, as that we
may perceive in them a greater consistency than was ima-
gined, of which the facts above stated are an instance.
Notwithstanding the difference of the species employed in
the experiments, they presented analogous results. They
were similar, whether presented by mammalia or by birds.
The facts being ascertained with animals of both classes,
it is needless to multiply examples, and we are warranted
in considering them common to warm-blooded animals.
The results, stated generally, are as follows : That the
successive losses by perspiration are subject to considera-
ble variations and alterations of increase and diminution,
when compared at short intervals, but constantly decrease
when considered at longer periods. The periods during
which the fluctuations take place in vertebrated animals
generally, may be pretty accurately determined. We have
always observed, in warm-blooded animals, the alterations
to take place with intervals of an hour, and this term may
be regarded as a general rule. On examining the whole
series of experiments upon vertebrata of different classes,
it was observed that the shortest intervals within which
the successive diminution took place were those of two
hours, and the longest, nine. In taking a mean of six, we
may hope to include almost all the cases, for even when a
longer space of time was necessary, three hours were suffi-
cient to determine a diminution, if not constant, at least
with little variation. In the greater number of cases, it
took place in successive intervals of three hours.
The first series of experiments upon the perspiration of
warm-blooded animals, having yielded results perfectly con-
formable to those which were obtained by corresponding re-
searches respecting the cold-blooded, it is probable that we
shall discover uniformity in others.
106 PERSPIRATION, OR EXHALTION.
It is almost needless to observe, that with reference to
temperature solely, the action of the air similarly influences
the perspiration of both warm and cold-blooded animals.
The same remark does not hold good with respect to dry
and moist air. The testimony of our senses is not adequate
to inform us of the effects of these two modifications of the
atmosphere. A dry air, by its property of absorbing moisture,
may cause perspiration to disappear, and a moist air by the
opposite quality allows it to accumulate on the surface of
the body. In the first case, it might be imagined, that dry
air diminished perspiration, and in the second, that humid
air increased it. May not sensibility, which in the higher
order of animals is so exquisite, and has so powerful an in-
fluence on their secretions, be so affected as to occasion
very different results from those which are purely physical ?
May not dry air produce such a constriction at the sur-
face of the skin, and on the internal surface of the lungs as
to diminish perspiration, and may not moist air occasion
such a relaxation as to cause the opposite effect ?
These considerations are sufficient to shew the uncer-
tainty which must exist on this question, if we have not re-
course to direct experiment, and are unwilling to follow the
analogy drawn from the facts connected with the cold
blooded vertebrata. It is surprising that the direct experi-
mental enquiry should never have been made. Delaroche
ascertained the comparative effects of dry and moist air
upon man at high temperatures, but this condition ma-
terially changes the effects of the agents. Other indivi-
duals who have examined the subject of perspiration, have
made experiments upon it at moderate temperatures, but
under such complicated conditions, that the results may be
attributable to other causes than those to which they have
been assigned.
PERSPIRATION, OR EXHALATION. 107
Sect. 2. — Influence of the Hygrometric state of the Air.
In order to compare the effects of dry and humid air,
all other conditions such as temperature, pressure, &c.
must be equal. To succeed in this most easily, the ex-
periments ought to be performed simultaneously.
As to humid air, the vapour should be transparent, and
not that which is termed vesicular, the state in which it is
exhibited in fogs. The other state of the atmosphere is the
most usual, and consequently the most important to be
known.
A guinea-pig was placed in a wire cage suspended in a
glass vessel, the sides of which had been previously wetted
and which was afterwards placed over water. The vessel
contained about 12 litres, or 732*5 cubic inches. It had
been previously ascertained that, under such circumstances,
the air rapidly arrives at extreme humidity. At the same
time, I suspended in a perfectly similar vessel, another
guinea-pig of the same litter, and as nearly as possible of
the same weight. The vessel was placed over two pounds
of quick lime, to absorb the moisture, and tallow was used
to intercept the air.# An hygrometer within, indicated the
progressive desiccation of the air. The external tempera-
ture was 1 5° cent, or 59° Fahr. Perfect dryness, although
easily obtained, at the commencement of the experiment,
could not be preserved during its continuance. The animal,
if passed through mercury into the vessel might have ac-
quired weight, and when introduced there, its perspiration
would furnish moisture, perhaps, faster than it could be
* The vessels or little chambers were not, however, perfectly air-tight,
which would have interfered with the respiration of the animals, they
were made of panes of glass, so put together as to allow the animals to
breathe, yet sufficiently close to secure the requisite hygrometric state.
108 PERSPIRATION, OR EXHALATION.
removed by the means employed to absorb it. By the means
which I employed, a high degree of dryness may be ob-
tained, equal to any met with in our climate, except at
very great heights.
The necessary conditions of the experiment, prevented
us from ascertaining directly the losses occasioned by the
alvine and urinary evacuations. We, however, sufficiently
fulfilled the condition of equality in this respect, by mul-
tiplying the experiments. Let us examine the results,
which we shall afterwards submit to another test.
Five guinea-pigs were placed in air of extreme humidity,
and five others in air comparatively dry, and whose dry-
ness went on increasing during the whole course of the
experiments, which lasted six hours, except on one occa-
sion which occupied eight. In all the cases, the losses in
the dry air were much more considerable than in the
humid. The influence of individual varieties did not fail
to exhibit itself, but it was only in varying the amount of
the difference. We see here a confirmation of the power-
ful action of the hygrometric state of the air, since it pre-
vails over all disturbing causes, originating from varied
combinations of organization and sensibility in individuals
of the same species.
In order to obviate the objection that the difference in
the losses arose from the difference in the weight of the
animals, the largest were placed in the moist air, in which,
from the experiments on cold-blooded animals, I concluded
that the losses would be least. Since, then, the superiority
in the weight of the larger animals, though counteracting,
did not compensate for the inferiority in the quantity lost,
the difference in the weight is only a fuller confirmation of
the result of the experiment.
It may likewise be objected, that the diminution of loss
in damp air is occasioned, not by a diminution of perspira-
PERSPIRATION, OR EXHALATION. 109
tion, but by that of the alvine and urinary evacuation. But
we had occasion to observe, that their excretions were rather
increased than diminished by the moisture of the atmosphere.
In order to verify these results in the case of other warm-
blooded animals, differing considerably in organization,
eight adult sparrows were submitted to similar experiments
with the same precautions. This species of animals has
the advantage of exhibiting less difference in weight, and
other particulars among individuals belonging to it, than
many others. The results were similar to those of the pre-
ceding experiments.
The numbers representing the amount of loss in an-
alogous cases were very similar, when the experiments
were not unduly protracted ; but when they lasted above
six hours, the want of food and other causes produced a
degree of suffering, which, without disturbing the relation
between the effects of dry and moist air, may increase per-
spiration by hurrying the respiration and circulation. The
state of respiration has a great influence in this respect.
Hitherto we have considered merely the differences in
the quantities lost, but we may approximate to the pro-
portion which they bear to each other. I determined the
average weight of the alvine and urinary evacuations of
eight individuals of the same species, exposed to the open
air of the room for six hours. This I subtracted from the
loss sustained by those which were confined in dry and
moist air for the same space of time ; the remainder fur-
nished the amount of the respective losses by perspiration.
Those in the dry air lost 1-04 grammes, or 15*9 grains : those
in the moist air only Ol? grammes, or 2*6 grains. Hence, it
follows, that the perspiration was six times greater in the
dry than in the humid atmosphere. It is evident, however,
that the properties might be rendered much greater, since
the air was far from its extreme point of dryness.
110 PERSPIRATION, OR EXHALATION.
These facts appear very simple, they are nevertheless
very complicated. They will be explained in the fourth
part of this work.
Sect. 3. — Influence of the Motion and Rest of the Air.
The effects of rest and motion in the atmosphere, have
an intimate connexion with the preceding facts. The
evaporation continually taking place from the bodies of
animals in an atmosphere not saturated with moisture,
creates for them a peculiar atmosphere more humid than
the rest of the air. Now, currents of air tend to prevent
this effect, by constantly renewing the air by which the
bodies are surrounded, and consequently to increase per-
spiration. Air at rest has the opposite effect. But in the
present case, the effect of the motion of the air is not con-
fined to this. The temperature of warm-blooded animals
raises that of the fluid in contact with them. Inordinary
circumstances, currents furnish supplies of colder air in
place of that which is thus warmed, and consequently oc-
casion a fall of temperature, which tends to diminish the
perspiration. Now it remains to be ascertained, whether
this last effect counterbalances the former.
To ascertain this point, I compared the losses from per-
spiration in the calmest air which could be procured, and in
air moderately agitated. This was effected in the following-
manner. The apparatus which were employed in the ex-
periments on the hygrometric state of the air, served, at
the same time, to prevent, as much as possible the agita-
tion of this fluid. But since during confinement in a close
vessel, the air is moistened by perspiration ; I compared
the losses occasioned by perspiration in a vessel of dried'
air, with the losses of animals of the same species, in the
PERSPIRATION, OR EXHALATION. Ill
open air of the room ; and I found that not only in mam-
malia but in birds, the losses were greater in the latter
case. Now, in consequence of the greater dryness of the
air in the vessels, the perspiration ought to have been
the more abundant ; but the slight agitation of the outer
air was more than sufficient to counterbalance this effect.
In comparing the foregoing results of experiments on the
perspiration of warm-blooded animals with the correspond-
ing cases of cold-blooded vertebrata, we observe a striking
similarity in the effects produced by the same physical
agents. This agreement tends to confirm both ; and the
confirmation is the greater, as the animals which furnish
them, present the greatest differences of structure in the
scale of vertebrata.
112
PART IV.
MAN AND VERTEBRAL ANIMALS.
CHAPTER I.
/ ON THE MODIFICATIONS OF HEAT IN MAN, FROM \
BIRTH TO ADULT AGE.
The results obtained in my experimental inquiries into the
influence of physical agents on other warm-blooded ani-
mals have been so uniform, that they may, by analogy, be
extended to man, although he can scarcely be made the
subject of the experiments themselves, and, for this reason,
was not mentioned in the preceding part.
Considered in reference to structure, man has been
placed in the class Mammalia.
Standing alone in the gift of intellect, he resembles other
mammalia, in the effects produced on organization by phy-
sical agents.
His life, like theirs, may be endangered by mechanical
forces, and his intellect merely enables him to resist those
forces by means of others of the same kind. Like them,
he suffers from the extremes of heat and cold, and would
sink under them, if his intelligence had not discovered the
means of setting their destructive influences in opposition
to each other. He is not, less than they, subjected to the
THE MODIFICATIONS OF HEAT IN MAN, &C 113
necessity of the constant contact and renewal of the air,
without which, his life would be extinguished as promptly
as that of other animals of the same class. He has no pri-
vilege from his organization capable of removing him from
the power of the physical laws which preside over the for-
mation of vapours, and by virtue of which, a part of the
water contained in his body is dissipated in the atmosphere.
He has not a sensibility so peculiar, that the function by
which the skin excretes upon its surface a part of the fluid,
is uninfluenced, as in other mammalia, by the condition of
the external temperature.
As a species, man may be affected peculiarly as to de-
gree, and in this respect he presents individual differences,
or the same individual may vary at different periods of his
life, but as to the manner in which he is affected, he comes
within the group studied in the preceding division of this
work, and the general truths there established must be
equally applicable to him.
We shall first consider how far the power of producing \
heat, is modified in man by the circumstance of age. y^
In treating of warm-blooded animals, we formerly ob-
served, that those which are born with their eyes closed,
when exposed to the air, in the spring or summer, lose their
heat, almost as rapidly as cold-blooded vertebral animals ;
while those whose eyes are open at birth, preserve, under
similar circumstances, a high and constant temperature.
In accordance with analogy, a new-born infant, born at
the full time, will have the power of maintaining a pretty
uniformly high temperature, during the warm seasons. If,
however, birth takes place at the fifth or sixth month,
the case is altered ; the pupil is in general covered by a
membrane denominated membrana pupillaris; which cha-
racter drawn, from the state of the eyes, may be considered
equivalent to the closure of the lids. We should, from
114 THE MODIFICATIONS OF HEAT IN MAN,
analogy, conclude that in such a child the power of pro-
ducing heat would be very feeble.
Let us now proceed to verify these conclusions by obser-
vation. An infant born at the full period, and separated from
its mother, if exposed to a moderate temperature, scarcely
varies in its temperature. It is true that we cannot strip it of
its clothes to judge of its power of maintaining warmth un-
der a long exposure to the air, but I have already shown
that this trial is unnecessary. Those new-born mammalia
which cool in the air almost as cold-blooded animals would
do, may in vain be well clothed. They cool, however, the
more slowly for it. The new-born infant does not then
belong to this group, confirming the conclusion drawn
a priori from the state of the eyes.
It remains still to be determined whether the human sub-
ject at birth produces less heat than afterwards. We shall
not, as in the case of inferior animals, expose individuals of
different ages to an artificially reduced temperature, in order
to ascertain their respective powers of producing heat, but,
as substitutes for such experiments, shall employ observa-
tions which will furnish satisfactory data. I have not
considered slight differences in the temperature of animals
as sufficient indication of a corresponding difference in their
power of producing heat, and I have, therefore, had recourse,
in the researches set forth in the third part, to the plan of
artificially reducing the temperature. But, after having
ascertained by this method that the young mammalia,
which are born with open eyes, produce less heat than
adults, we may take advantage of the observations made on
their natural temperature. All the animals of this group,
which I have examined, have at birth, and for some time
after, a temperature inferior to that of their parents. I have
observed in this respect a difference of one or two degrees
centigrade, or from 1° 8 to 3° 6 of Fahrenheit. This, for
FROM BIRTH TO ADULT AGE. 115
our present purpose, is an important index of the difference
in the power of producing heat. If a similar difference
exists in the human temperature at the two periods of life,
we shall not hesitate to regard it as a proof of a difference
in calorific power, like that which we have demonstrated
with respect to other mammalia.
The temperature of the adult man has frequently been
taken, and as it varies in different individuals, it is impor-
tant to ascertain its limits, and the average. It varies also
in different parts of the body. In the mouth it is generally
rather higher than in the external parts of the trunk, some-
times to the extent of one degree (of the centigrade ther-
mometer.) To establish, therefore, a comparison between
the adult and the new-born infant, the thermometer should,
in each, be applied to the same part of the body.
In thus taking the temperature of twenty adults, it was
found to vary from 35° 5 to 37° cent, or 96° to 98° Fahr.,
the mean being 36° 12 cent, or 97° Fahr., which agrees with
the best observations. In ten healthy infants, from a few
hours to two days old, in the wards of an hospital, under
the care of my friend M. Breschet, the limits of variation
were from 34° to 35° cent, or 93° to 95° Fahr. ; the mean of
the whole number was 34° 75 cent, or 94° 55 Fahr. Their
temperature is, therefore, inferior to that of adults ; a rela-
tive difference rendered probable by analogy, and confirmed
by observation. I should have laid no stress on so slight a
disagreement, if numerous experiments on warm-blooded
animals had not proved that this difference in natural tem-
perature coincides with a difference in the power of produc-
ing heat, at the different periods of life.
Another analogical conclusion which I wished to verify
related to the temperature of infants prematurely born. The
facilities for doing so do not often occur, but through the
kindness of Dr. Dagneau, who attended a lady who was
i 2
116 THE MODIFICATIONS OF HEAT IN MAN, &C.
my patient also, I had an opportunity of ascertaining the
temperature of a healthy seven-months' child, within two
or three hours after birth. It was well swathed, and near
a good fire, but the temperature at the axilla did not ex-
ceed 32° cent, or 89° 6 Fahr. Before the period when this
child was born, the membrana papillaris usually disappears.
If it had been born pretty long before the disappearance of
the membrane, there can be no doubt from what has been
above stated, that its power of producing heat would be so
feeble, that it would scarcely differ from that of mammalia
born with their eyes closed.
117
CHAPTER II.
ON THE INFLUENCE OF COLD ON MORTALITY AT DIF-
FERENT PERIODS OF LIFE.
The preceding facts being established, let us now proceed
to the consequences which flow from them. When the fa-
culty of evolving heat is not the same, the vitality will be
different. First, the relation to the external temperature
will be changed. The need of warmth and the power of
supporting cold cannot be the same where the internal
source of heat has not the same activity. There is scarcely
any agent which exerts a more powerful influence on life
than the temperature of the atmosphere ; hence, its rela-
tions are amongst those which it is the most important to
know. There is, moreover, no agent which we have more
in our power to modify and adapt to our necessities.
When circumstances prevent our doing so, as when we are
exposed to the open air, we have other resources to supply
the deficiency. Hitherto our care in this respect has mere-
ly been guided by instinct, or by that kind of observation
which every body can make. But it requires a more inti-
mate knowledge of our relation to the external temperature,
properly to regulate the employment of means, expedient to
protect us from the injurious influence of heat and cold.
Let us first examine how far these relations vary accord-
ing to the modifications dependent on age, as set forth in the
preceding chapter. Instinct leads mothers to keep their in-
fants warm. Philosophers by more or less specious reason-
118 THE INFLUENCE OF COLD ON MORTALITY
ing, have, at different times and in different countries, in-
duced them to abandon this guide, by persuading them
that external cold would fortify the constitutions of their
children, as it does those of adults. We will examine this
question by the test of experience, in order to be governed
by the observation of nature, rather than by the varying
opinions of men.
We shall begin with those young warm-blooded animals,
which produce the least heat ; viz. mammalia, born with
closed eyes, and birds hatched without feathers.
They are, for the greater part of their time, secluded from
the effects of external temperature, being warmed in their
nests by contact with each other, and more especially with
their mother. Under such circumstances, therefore, their
heat cannot differ much from that of adults. But if ex-
posed to the air in spring or summer, in the early stages of
life, their temperature would not exceed that of the atmo-
sphere by more than a very few degrees. This fact, though
not amounting to proof, renders it probable, a priori, that
the higher temperature occasioned by seclusion and con-
tact with the mother is essential to the support of life.
On 12th February 1819, a kitten, newly littered, re-
moved from its mother, and exposed to the air, at the tem-
perature of 14° cent, or 51° Fahr. being cooled down in nine
hours to 18° cent, or 64° 4 Fahr. became stiff, and almost
incapable of executing the slightest movements.
The following month the air of the room being 10° cent,
or 50° Fahr., I exposed two kittens, of one day old, and hav-
ing a temperature of 37° cent. 98° 6 Fahr. In 2h. 25,
the temperature of one was reduced to 17° cent, or 62° 6
Fahr. and that of the other to 18° cent, or 64° 4 Fahr.
They had become stiff and almost insensible.
In the month of January in the same year, four puppies,
littered the day before, were of the temperature of 35° to 36°
AT DIFFERENT PERIODS OF LIFE. 119
cent, or 95° to 97° Fahr. The air of the room was 1 1° cent,
or 52° Fahr. The cooling which they underwent from nine
in the morning till ten at night, lowered their temperature
to 13° and 14° cent, or 55° 4 and 57° Fahr. They were
then so enfeebled that they were almost motionless.
The symptoms of weakness and suffering soon after the
young animals are exposed to the air, increases as their
temperature sinks. The same circumstances occur with
those young birds which produce the least warmth when
hatched.
Although the diminution of temperature thus occasioned
by exposure to the air, would ultimately prove fatal to these
young animals, it is remarkable how long they are capable
of enduring a considerable reduction of temperature. New-
born puppies or kittens may live two or three days at a
temperature of 20° cent, or 68° Fahr. and even 17° or 18°
cent, or 62° 6 or 64° 4 Fahr. But the air must not be too
cold, or they would soon be deprived of sense and motion,
and in a short time this apparent death would become real.
When they appeared on the point of expiring, I easily re-
stored animation by placing them before the fire, or by im-
mersion in a bath. These means, if promptly applied, may
even prove effectual when they are quite motionless, and,
to all appearance, dead.
By the above facts we find that this group of young ani-
mals, both birds and mammalia, support a considerable re-
duction of their temperature, and may even be repeatedly
exposed to this trial, provided that they be not left too long
in the state of reduction, and that proper care be taken in
the restoration of warmth. The exposure is, however, in-
jurious to the animals, and if very often repeated, or too
long continued, is fatal.
This facility of recovery, after great reduction of tempera-
ture, does not continue in the same degree with the progress
120 THE INFLUENCE OF COLD ON MORTALITY
of life. I cooled artificially birds of various species, such as
jays, magpies, orioles, &c. when they were almost entirely
fledged. The temperature of some was reduced to 20°
cent, or 68° Fahr., that of others to 18° cents, or 64° 4
Fahr. They had been exposed to the cold but for a short
time. They were then very weak and seemed ready to ex-
pire. However, they did not fail to recover as rapidly, and
apparently as completely as younger birds, but this recovery
was temporary ; they mostly died in one or two days.
The reduction of the bodily temperature is, then, less
injurious, in its permanent effects, in proportion to the
youth of the animal. Now, there is here another relation
which is deserving of notice ; we see that it is according as
the power of developing heat increases, that of supporting
a reduction of temperature diminishes ; and, to be con-
vinced of the intimate connection between these two cir-
cumstances, let us compare the adults of different groups
of vertebral animals ; the cold-blooded animals, the hyber-
nating mammalia, and other warm-blooded animals. In
this arrangement they form a scale in which animal heat
goes on increasing. Reptiles and fishes, at the bottom of
the scale, are, as is well known, those which best support a
reduction of temperature ; and the hibernating mammalia,
inferior, with regard to temperature, to other warm-blooded
animals, have, on the other hand, the advantage of being
able to survive a reduction of temperature which would
destroy the latter.
In the same manner I have shewn that, in young warm-
blooded animals, the capability of supporting reductions of
temperature is inversely in proportion to their power of pro-
ducing heat. I shall now point out the necessity for this.
Whatever degree of care parents may take of their young,
they cannot always remain with them in order to maintain
their temperature at a high degree, if they are of that class
AT DIFFERENT PERIODS OF LIFE. 121
of animals which are born with eyes closed, or without
feathers. As soon as they leave them to provide subsis-
tence, the temperature of their young begins to be reduced,
and if this reduction were as injurious as it is to those
animals which produce more heat, the greater part would
perish.
Other young warm-blooded animals are not exposed to
similar reductions of temperature, because they are born with
a more abundant source of heat. But if the external tem-
perature were such that it lowered that of their bodies to the
same degree, and as frequently, as with the groups of young
animals above-mentioned, a much greater mortality would
prevail among them. Hence the danger to which they
would be exposed, if born in winter ; hence, also, may be
perceived the end which nature had in view by generally
avoiding their production in that inclement season. This
is usually the case with wild animals which are born with
the greatest development of heat. However considerable
this may be, it would not enable them to support the cold
of our climate in the early periods of life ; and as they are
at the same time stronger, more active, and more indepen-
dent, their mother could not secure them from the incle-
mency of the air. They are usually born, therefore, in
spring, or at the beginning of summer, during the fine
weather. Their power of producing heat gradually in-
creasing, they are more capable of resisting the severity of
the succeeding winter.
The following is a general review of the facts relative to
the influence of cold, at the different periods of life.
We must distinguish two things — the cooling of the
body, and the temperature capable of producing it. The
cooling of the body, without regard to its cause, is less in-
jurious in proportion to the youth of the animal.
Lower the temperature of two animals of the same spe-
122 THE INFLUENCE OF COLD ON MORTALITY, &C.
cies an equal number of degrees, the younger will suffer
less, and will recover more perfectly.
But in order to lower the temperature of animals of dif-
ferent ages, different degrees of external cold will be neces-
sary, being lower, the nearer the animal is to adult age. If,
on the one hand, young animals suffer less from the same
reduction of warmth, on the other hand they cool more
readily. It is on this last circumstance that the mortality
in warm-blooded animals, at different periods of life, from
birth to adult age, principally depends, so far as it is the
result of the influence of external cold.
123
CHAPTER III.
MOMENTARY APPLICATION OF COLD.
Although animals previously exposed to cold may have
regained their temperature, it does not follow that they
still retain to the same degree the power of producing
heat. If this be the case, on repeating the exposure to
cold, about the same time will be sufficient to enable them
to recover their temperature. But I have observed, in cool-
ing and warming successively the same individuals, that
the time required for the recovery of the original tempera-
ture became longer by repetition, which proves that their
power of producing heat was thereby diminished. With-
out that knowledge of the facts which we have unfolded
regarding animal heat, we might be tempted to attribute
the continuance of the sensation of cold long after the
cessation of its cause, merely to the natural duration of
all strong sensations. But there is more than the prolon-
gation of a strong impression, more than a simple affec-
tion of the nervous system ; there is an alteration of func-
tion, a diminution in the production of heat.
In a severe winter, in which the Seine was frozen, a
young man attempting to cross it, broke the ice and fell
into the water, but being strong and active he succeeded in
getting out. His health did not suffer, but for three days
he had a continual sensation of cold. This case is analo-
gous to those mentioned above. A potent chill acted on
124 MOMENTARY APPLICATION OF COLD.
the faculty of generating heat, producing a sensible dimi-
nution in it, greatly exceeding in duration the length of
time in which the cold was applied. And even if the
sensible heat were fully restored after such an exposure,
its influence would not have been entirely at an end. The
calorific function had not recovered all its lost power.
We do not know at what interval one may again be ex-
posed to a degree of cold, which might before have been
tolerated without inconvenience.
125
CHAPTER IV.
MOMENTARY APPLICATION OF HEAT.
After an exposure to cold, sufficient to diminish the
power of producing heat, continuance in a high tempera-
ture tends to the recovery of this power ; for, in exposing
animals to successive applications of cold, their temperature
will fall the more slowly, the longer they shall have been
subjected to the influence of warmth. It follows, therefore,
that the effect of the application of a certain degree of
heat is continued after the cessation of the cause, furnish-
ing the counterpart of what we have stated with respect
to the application of cold.
Hence, we see that those who are liable to frequent ex-
posure to severe cold, are rendered more capable of sup-
porting it, by subjecting themselves, in the intervals, to a
high temperature ; — a practice adopted by northern na-
tions, and justified by the foregoing facts. Attention
should be paid to this principle, that the transient applica-
tion of heat occasions effects which are continued beyond
the time of the application, and that it operates whenever
the system stands in need of heat. Beyond this point
other effects ensue which form the subject of the next
chapter.
126
CHAPTER V.
INFLUENCE OF THE SEASONS IN THE PRODUCTION
OF HEAT.
No phenomenon of heat discovered by the thermometer,
has excited more astonishment than the uniformity of tem-
perature maintained by man and the higher classes of
auimals. — As soon as the formation of vapour was ascer-
tained to be a cooling process, this principle was made use
of, to explain the uniformity of animal heat. But although
perspiration, by moderating the increase of heat has un-
doubtedly some influence in maintaining a uniformity of
temperature, yet there is another very important element
which enters into the solution of the question.
Warm-blooded animals may be divided into two classes,
in regard to the influence of the seasons : viz. those
whose constitution is perfectly in harmony with the cli-
mate, and those whose constitutions are not adapted to it.
The first undergo changes corresponding to the season,
which allow them the free use of their powers, and that
enjoyment of life which constitutes health. According as
the temperature falls, their internal source of heat increases,
until it attains its maximum in winter, and afterwards de-
clines with the elevation and duration of the external tem-
perature. Here, then, is a new element which should
enter into the explanation of the uniformity of animal tem-
perature. A balance is thus maintained between the heat
INFLUENCE OF THE SEASONS, &C 127
coming* from without and that which is developed within,
the excess of the one supplies the deficiency of the other.
But the system only acquires this power of accommo-
dating itself to the external temperature with the slow pro-
gress of the seasons ; at least it is only thus that it is
acquired in the highest degree. In summer, a degree of
cold which we bear in winter, would take the body as it
were by surprise and unprepared. The power of produc-
ing heat being then reduced to its minimum, the loss would
be insufficiently repaired. In this respect, our states in
summer and winter differ in the same manner, though not
in the same degree as young animals differ from adults.
In the former, the increase of the power of producing heat
takes place through the progress of organization whilst
under the influence of a mild temperature ; in the latter by
the influence of cold in degree and duration suited to their
constitution.
In the same way, the winter state being acquired, a
transient elevation of the external temperature, if it be
not excessive, has but little effect on the power of produc-
ing heat, which continues to be developed in abundance.
To reduce this power, without injury to the health, the
heat must be raised slowly, and maintained during a long
period.
These changes do not however take place in all animals.
There are some whose constitution is not adapted to so
great a range of the external temperature. The cold which
they can sustain without inconvenience is much less, be-
cause they have not the same resources for repairing the
loss of heat. When reduced below this limit a fall of tem-
perature produces an effect the reverse of what has been
above described ; instead of increasing the production of
heat, it diminishes it. The type of such constitutions is
exhibited in young warm-blooded animals and in hiberna-
128 INFLUENCE OF THE SEASONS IN
ting mammalia. They present its operations in the most
marked degree, but traces of them, whether found in man or
in other warm-blooded animals, though more feeble, are not
less truly of the same nature. When we look at the hiber-
nating mammalia, with reference to their peculiarity of
becoming torpid, it appears to separate them by an im-
mense interval from other animals of their class, but when
we consider them with reference to the function with which
we are now occupied, and which seems to be ultimately
connected with that peculiarity, we pass by insensible
degrees to those mammalia which are in appearance the
furthest removed from them. We have shewn that the
hibernating mammalia occupy the lowest ranks in the
scale of the production of heat amongst adult warm-
blooded animals. We have made one group of them
without distinction, because they present phcenomena in
common — a like diminution in temperature, and a long-
continued and profound torpor. — But they do not all
exhibit these conditions to the same degree under similar
circumstances. The unequal effects which the same de-
gree of external temperature produces on the warmth of
their bodies shew that the different species differ consider-
ably in their power of producing heat. Amongst the spe-
cies which I have mentioned, bats on the one hand, and
marmots on the other, may be placed at the two extremes
of the scale. Bats cool the most readily, they differ much
from the species which immediately follow them, and a
considerable interval exists between them and the marmots.
There are some adult species of the class mammalia,
which, though not passing the winter in a torpid state,
closely resemble hibernating animals, in their feeble power
of producing heat. Mice are of this number. On ex-
posing these animals to a moderate cold in winter, I have
been surprised at the reduction of their temperature, and
THE PRODUCTION OF HEAT. 129
this circumstance served to explain to me the use of a very,
singular habit among them. They make nests at all times,
not for their young only, but for themselves. It is known
that confined in small cages they do not propagate. I
kept in this way some of both sexes and various ages, and
observed them, in seasons when I should not have suspect-
ed that they required much heat, carefully forming nests
like those of birds. I placed near them bits of straw and
flocks of cotton, which they pulled through the bars of the
cage for this purpose. Thus we see that they seek to pre-
serve the little heat which they develope, and which is ne-
cessary to their existence, for, when exposed to the air they
often perish from a degree of cold which, to us, would ap-
pear moderate. In taking up their residence with man,
they have not only the advantage of more abundant food,
but also additional facility for guarding against the effects
of cold.
This fact leads us to recognise the group of warm-blood-
ed adult non-hibernating animals, comprehending the
species the least adapted to increase their calorific power,
under the influence of the gradual reduction of the external
temperature. Most of those animals which burrow or inhabit
caverns, and crevices in rocks or holes, in walls or trees,
are of this class. Other causes, doubtless, concur to in-
duce the choice of these retreats, as the necessity of avoid-
ing surprise and of finding a place of refuge, or for a store
of provisions against a scarcity. And if they are sometimes
chosen only as a magazine, they likewise serve as a pro-
tection from the cold, which many of these animals cannot
bear with impunity. This is particularly evident with those
animals which carefully line their dwellings with materials
suited for the retention of warmth.
A similar difference of constitution prevails among men
inhabiting the same climate. Some, and these constitute
K
130. INFLUENCE OF THE SEASONS TN
the majority, experience, a salutary effect from the gra-
dual reduction of temperature, not from blunted sensibility,
but from increased power of producing warmth. Others,
not having the same resources in themselves to counteract
the loss of cold which they undergo in winter, are obliged
to have recourse to auxiliary means of protection from the
effects of winter. There are some who regain their heat
with difficulty, even when the cold is moderate, and they
require a greater elevation of temperature in their rooms.
This class is more numerous than is suspected. It is not
confined to chilly persons; for the injurious effect of cold
does not always manifest itself by the "painful sensation to
which we give the same name : it may be indicated by very
different sensations ; by various states of indisposition, pain
and uneasiness, differing from the peculiar sensation gene-
rally produced by exposure to cold. The absence of this
sensation makes us mistake the cause, and consequently
fail in applying the remedy.
We have seen, from the experiments on warm-blooded
animals, that the temporary application of cold acts upon
constitutions of this kind, by diminishing the power of pro-
ducing heat, and that this influence extends beyond the
period of the cooling process. When, therefore, the ex-
posure to cold is lengthened, the effects of each portion of
time are added to those of the succeeding portions. Thus,
individuals of this class, by the very duration of the same
degree of cold, undergo a progressive diminution in their
power of producing heat.
This observation applies to a very remarkable pheno-
menon presented by hibernating mammalia. Pallas informs
us, in his excellent work on some new species of the family of
dormice, that, the external temperature remaining the same,
the torpor of these animals went on increasing with the du-
ration of the cold. M. de Saissy has made the same ob-
THE PRODUCTION OF HEAT. 13l
servation, which I have also had an opportunity of verify-
ing; but this effect is not unlimited. In like manner,
the continuance of the same slight cold increases the power
of producing heat in constitutions adapted to the climate,
but this increase is necessarily limited.
K2
132
CHAPTER VI.
ASPHYXIA.
We have already shown, by repeated observations, the in-
timate connexion which subsists between the power of
living for a time with a suspension of respiration and the
power of producing heat. Accordingly we divided the young
mammalia into two classes. First, Those which produce so
little heat that they have, as it were, no temperature of their
own. And second, those which produce enough to maintain
a high temperature when the air is not too cold. The first live
the longest without air ; the others for a short time. The ex-
ternal character serving to indicate the class to which any
given species ought to be referred, is derived, as has been
observed, from the state of the eyes. Now the infant is
born with its eyes open, and belongs to that class which
produces most heat, from which we may conclude that it
will, when deprived of air, live a much shorter time than
animals of the first class.
When we speak of the duration of life in asphyxia, it is
important to recollect that we only judge by the outward
signs which are manifested during the experiment. These
signs consist in movements voluntary or involuntary; and
when the animal no longer moves spontaneously, we try
to excite these motions by pinching it. As soon as this
means is ineffectual, we put an end to the experiment.
There still, however, exist internal movements ; the heart
ASPHYXIA. 133
continues to beat, but as we cannot excite visible move-
ments and the animal does not spontaneously perform
them, it is then in the state of apparent death.
I shall not here treat of the duration of this state, nor of
the conditions which limit it. It is a question connected
with an other order of phenomena requiring distinct re-
search, and must be reserved for another occasion.
We shall confine our attention to apparent death in-
duced by submersion in water.
Whether the water be aerated or not, the effects upon
mammalia are the same. The phenomena which they
present are very different according to the period of the ex-
periment. In the first moments, the motions are varied,
repeated, continuous, and evidently voluntary ; the animals
endeavour to rescue themselves from their painful situation;
but soon voluntary motion ceases, and then there is evi-
dently loss of consciousness. Up to this time the mouth
remains shut, oris only accidentally opened. But after the
animal has lost consciousness, the motions become involun-
tary; at first suspended for a short interval, they are after-
wards performed in an automatic manner, with a certain
regularity in their motion and their action. Every part of
the body participates ; the mouth opens wide, the chest ex-
pands, the trunk bends forward, the limbs approach each
other, the muscles relax, and the body becomes motionless.
These motions are repeated in nearly the same manner till
towards the close of the experiment. Then the trunk
gradually ceases to bend, the limbs to be drawn together,
the chest to be expanded, at least to a perceptible degree,
but the mouth continues at intervals to open, though less
widely than before, and this motion is the last to cease.
It is remarkable that the voluntary motions are always of
short duration, even in individuals which live the longest
in asphyxia- Thus puppies, kittens, and rabbits, recently
134 ASPHYXIA.
brought forth, although they live in that state for half an
hour, commonly lose voluntary motion and consciousness
in three or four minutes. The fact has repeatedly arrested
my attention.
Buffon was then deceived in his experiments on the sub-
mersion of puppies, when he thought that they did not suf-
fer from the suspension of respiration for half an hour. As
they were in milk he was unable to see the phenomena
which they presented. This celebrated naturalist was de-
ceived by the facility with which the puppies were restored.
The fact was, that involuntary movements not having
ceased, respiration immediately went on in air ; yet one of
the puppies which had been three times subjected to the
trial died, not indeed immediately after the experiment, but
the same day. We must here observe that puppies will
exhibit signs of life during more than half an hour's submer-
sion. I have seen them live under water fifty-four minutes,
but this case is rare. If left in water until they no longer
move, either of themselves or when excited, they would not
be restored by exposure to the air ; at least I have never
seen this take place either with them or any other species
of mammalia. I offer this observation only incidentally,
for it relates to the possibility of recalling life after appa-
rent death ; a subject which I do not propose to treat of
here. I shall merely add that man possesses one of the
most favourable conditions for restoration by exposure to
the air.
From the description which I have given of the pheno-
mena of life during submersion, we may easily judge whe-
ther the means proposed by Buffon in the following pas-
sage could obtain the end which he had in view in the
repetition of the experiment.
" I have not," he says, " pursued these experiments fur-
ther, but I have seen enough in them to persuade me that
ASPHYXIA. 135
respiration is not so absolutely necessary to the new-born
animal as to the adult, and that it might perhaps be possi-
ble, by proceeding carefully, to prevent, by these means,
the closure of the foramen ovale, and produce excellent
divers ; and species of amphibious animals, equally capable
of living in air and in water."
Let us suppose that the frequent repetition of submer-
sion, commenced at birth, could preserve to the adult, the
same mode of vitality which it possessed in infancy, and by
which it was enabled to live a long time without breathing,
it must have, to be a good diver, the use of its senses and
voluntary motion : now, we have seen that the newly born
mammalia generally lose consciousness in three or four mi-
nutes, and that they have, in this respect, but little advan-
tage over adults. I have often ascertained, at the swim-
ming schools of Paris, the length of time that the best
divers can remain under water, and have found three mi-
nutes to be the utmost. There are, indeed, few men who
are able to dive for so long a time.
We have seen from the considerable power of producing
heat which the infant possesses, that it belongs to that class
which at birth are unable long to bear submersion in
water.
Warmth, whether produced in the system or derived
from without, produces the same effects on the mode of
vitality.
There is no physiological character which more emi-
nently distinguishes the cold-blooded from the warm-
blooded vertebrata, than the great difference in the dura-
tion of their life when deprived of air, but this character
depends less on their own nature, than on the circumstances
in which they are placed. We have seen that the batrachian
reptiles can live two or three days in water deprived of air ;
but under what circumstances does this happen ? This
136 asphyxia.
long duration of life depends on two external conditions:
1st, That the water in which they are placed is at 0° cent,
or 32° Fahr. or a very little above it ; and, 2dly, That the
air shall have been, for a long time before the experiment,
at nearly the same temperature, in order that the constitu-
tions of the animals may have undergone a modification,
dependent on this long duration of cold. (See the First Part,
Chap. II.) If the same experiment be made in summer,
and with water at 20° cent, or 68° Fahr. they live about
an hour only, varying more or less, according to the degree
of preceding warmth. We may see from this that they
scarcely differ from some of the new-born warm-blooded
animals, such as puppies, which, as I have shewn above,
may live fifty-four minutes in water of the same tempera-
ture. If instead of this degree, we raise the water to
40° cent, or 104° Fahr., the mean temperature of warm-
blooded animals, batrachian reptiles plunged in it will not
live longer than the adult mammalia. The same is the case
with fishes, especially with those of small species. With
others the difference amounts merely to a few minutes. Grey
lizards, in the same circumstances, lived about six minutes.
Hence we see that heat, whether internally or externally
produced, has the same influence on the duration of life in
asphyxia.
With reference to the influence of cold, it is evident, that
in experiments upon warm-blooded animals we cannot ob-
tain results equally decisive with those derived from the
cold-blooded vertebrata. In the first place, the mammalia
and birds cannot, whatever may be their age, endure so
great a reduction of temperature as reptiles and fishes ; and
secondly, at an equal reduction of temperature, warm-
blooded animals cannot, in general, remain the same length
of time. From these considerations we should be led to
conclude, that the hibernating mammalia which are sus-
ASPHYXIA, 137
ceptible of a considerable reduction of temperature, and are
also capable of living a long time in this state under the
influence of a cold air, would bear a strong resemblance to
reptiles and fishes in the power of living a long time with-
out the contact of air. It is easy to foresee the probable
duration of their life when they are deprived of air by sub-
mersion in summer. Let .us recollect that in this season
they have a high temperature like other mammalia, and
that they have been subjected to the influence of this tem-
perature for the whole course of the preceding fine weather.
They will, therefore, be in the condition most conformable
to the duration of life in asphyxia.
I asphyxiated bats in water at 20° cent, or 68° Fahr., at
a period when they were not torpid ; they lived only four or
five minutes. Let us now change the conditions of the ex-
periment ; let some hybernating animal have undergone
the greatest reduction of temperature of which it is capable ;
let it have lived a long time in this state, under the influ-
ence of cold air ; it is easy to foresee that, participating
then in the winter mode of vitality of the cold-blooded ver-
tebrata, it will present analogous phenomena in the dura-
tion of life, when deprived of air. Spallanzani furnishes us
with some interesting facts, shewing the correctness of this
conclusion. He placed in a receiver containing carbonic
acid, at the temperature of 12° cent, or 53° 6' Fahr., a
marmot completely torpid. It shewed no sign of uneasi-
ness during the whole course of the experiment. Spallan-
zani took it out at the end of four hours, without its having
appeared to suffer from the ordeal, and certainly it would
have lived longer if left in the gas. We may remark, in
addition, that this gas is very deleterious, that it acts not
merely by depriving the animal of the contact of atmo-
spheric air, but also by a property tending to extinguish
life.
138
ASPHYXIA.
The facts just mentioned prove that temperature has a
similar influence upon all the vertebrata, in prolonging or
shortening the duration of life in asphyxia. The range of
temperature at which these observations were made lies
between 0° and 40° cent, or 32° and 104° Fahr. At the
higher limit there is a remarkably slight difference in the
times that the animals can live without breathing. It is
at the lower degrees only that the differences become more
decided, according to the species, and increase in proportion
as we approach the inferior limit.
Although the general influence of temperature as above
stated, may be considered as demonstrated, it is by no
means pretended that, amongst the complicated phenomena
of life, other causes do not concur to modify the duration of
life under privation of air.
When an animal is cut off from communication with the
air, as in submersion, the circulation continues, but the
blood loses its arterial quality, and becomes venous. Does
the circulation of this venous blood contribute to the sup-
port of life ? In the first chapter of this work, this ques-
tion has been decided in the affirmative, with regard to rep-
tiles. Is it also the case in warm-blooded animals ? I made,
with kittens, experiments similar to those related in the first
chapter upon reptiles, and found that the kittens, whose
circulation was prevented by cutting out the heart, when
plunged in water, lived in general but a quarter of an hour ;
whilst others, whose circulating system was left entire, gave
in water, at the same temperature, signs of life for about
half an hour.* In experiments upon adult warm-blooded
animals, the influence of the circulation of venous blood
cannot easily be seen, on account of the rapidity with which
the privation of air causes apparent death, and renders it
* Some experiments made on young rabbits by Le Gallois tend to the same
conclusion.
ASPHYXIA. 139
useless to endeavour to determine minute differences, which
perhaps cannot be made perceptible ; but there can be no
doubt that the circulation of venous blood contributes to
maintain the life of those animals after the cessation of ex-
ternal motion, and during that state which we call apparent
death.
These observations lead us to examine the function upon
which temperature acts, according to its degree, so as to
prolong or shorten life during asphyxia.
We may suppose that temperature between 0° and 40°
cent, or 32° and 94° Fahr. acts, either directly or indirectly,
on the motion of the heart of asphyxiated animals. As we
have proved that circulation contributes materially to pro-
long the life of those animals which live long without air, it
follows that the different degrees of activity of the heart may
exercise different degrees of influence upon the duration of
life. It is a fact that the rapidity of the heart is very differ-
ent in animals plunged under water, according to the tem-
perature of that liquid. In reptiles, as in young mammalia,
it is slowest at 0° cent, or 32° Fahr. and very rapid at 40°
cent, or 104° Fahr.
We shall suppose that the degree of rapidity of the heart
which is the best adapted to prolong the life of asphyxi-
ated animals, is that which is determined by the tempera-
ture at which they live the longest, and we shall inquire if
this same temperature has not a special action upon the
nervous system favourable to its functions ? I convinced
myself of this in the following manner. Towards the end
of December, the previous temperature having been very
low, the hearts were taken from eight frogs. Four were
placed in water at 20° cent, or 68° Fahr., and four others in
water at the freezing point. The first set lived on an aver-
age an hour and three minutes, the second eight hours and
fifty-five minutes. Temperature, therefore, acts upon the
140 ASPHYXIA.
frogs when circulation is destroyed, and which are, as it
were, reduced to the exclusive action of the nervous system,
in the same manner as in those whose circulation is in full
activity. The hearts were cut out of three new-born kit-
tens ; one was put in water at 20° cent, or 68° Fahr., ano-
ther in water at 40° cent. 104° Fahr., and the third in
water at 0° cent, or 32° Fahr. The first lived thirteen
minutes and thirty seconds ; the second seven minutes; and
the third i:ve minutes. Now these animals lived only
by the nervous and muscular systems, and if we com-
pare the result of these experiments with those related in
Part III. Chap. IV. performed on animals of the same
species, whose circulation was not destroyed, and which
were placed in the same circumstances, it will be seen that
the temperature exercised upon both an analogous influence.
For it was in water at 20° cent, or 68° Fahr. that they lived
the longest, much shorter at 40° cent, or 104° Fahr., and
the shortest at 0° cent, or 32° Fahr. Temperature, there-
fore, within these limits, exerts a direct influence on the
vitality of the nervous system.
141
CHAPTER VII.
ON THE MODIFICATIONS OF RESPIRATION DEPENDING
UPON SPECIES, AGE, &C.
If animals differ much in the duration of life, when the
contact of air is cut off, they differ no less in their commu-
nications with air by respiration. This pabulum vita is far
from being consumed by all in the same proportion. We
have given several examples of this in the Third Part of this
wort, when treating of warm-blooded animals ; but the
comparison of these vertebrata with others which breathe
in air, presents differences much more considerable. Let us
select them of about the same size, and at the period when
the cold-blooded vertebrata enjoy all their activity. Place
a frog upon an open-work partition, in a receiver containing
a litre, or 61 cubic inches, of air, over a strong solution of
pure potass, to absorb the carbonic acid produced by re-
spiration ; do the same with a yellow-hammer of the same
size ; the latter will live about an hour, the frog from three
to four days. This great difference does not arise from the
frog's being able, after having consumed all the air which
can support respiration, to live long without that function.
It breathes continually, as long as the air is respirable,
and quickly dies, after it ceases to be so. It was shewn
in the first part of this work, that these animals when de-
142 THE MODIFICATIONS OF RESPIRATION
prived of the contact of air in summer, could not live above
one or two hours. Neither does the great difference in the
duration of life depend on the frog's being able to derive
greater advantage from the air, by depriving it of its last
particles of oxygen. . When the experiment is made, as
mentioned above, by absorbing the carbonic acid as it is
formed, the bird has the power of consuming a greater quan-
tity of oxygen. So little of it remains at the end of the ex-
periment, when the air is no longer capable of supporting
life, that the proportions scarcely differ in the two cases.
The enormous disproportion in the duration of life of the
reptile and the bird, in equal quantities of air, essentially
depends on the comparative rapidity with which they con-
sume the air, that is admitted : but it may be well to fix
our attention on some of the conditions of this difference.
To consider only the lungs : it is manifest that the sur-
face in contact with the air is more extended in the bird,
not because the lungs are larger, but because the air-cells
are more numerous. The extent and frequency of the re-
spiratory motions are also an indication of the great quan-
tity of air which enters the lungs of birds. Besides, it is
known that their lungs contain much more blood, and it is
principally to the blood that we attribute the power of alter-
ing the air. All these conditions in favour of birds are to
be referred essentially to multiplied communication with the
air. They may be considered as physical data, since they
consist in relations of quantity, but there are undoubtedly
others of a different kind, which are of no less importance.
If the blood have a great influence by its quantity, will it
not likewise have by its quality ? Simple inspection may
satisfy us that the blood of the frog is more watery than
that of the bird. From this single difference must arise a
different relation between the blood and the air, for no one
will attribute the alteration of the air to the watery part of
DEPENDING UPON SPECIES, AGE, &C. 143
the blood, but rather to the animal matter which it contains.
Of this the proportion is necessarily less in the reptile.
There is still another difference which is quite fundamental.
The blood to the naked eye appears void of organization,
but by the help of the microscope it has been long known
to contain particles of a regular figure. According to the
last researches of Sir Everard Home in England, and of Pre-
vost and Dumas at Geneva, these particles always consist of
a colourless spheroid, with a red covering.* Although
these particles are elliptical both in the reptile and in the
bird, they are of very different dimensions, being much
larger in the former. Prevost and Dumas have given the
measurements in their excellent treatise on the blood.
Thus, the quality of the blood in the two species mentioned,
differs essentially both in the number and the dimensions of
the particles.
The same conditions of organization which retard the
consumption of air in the frog, as compared with the bird,
exist in all reptiles and fishes.
Mammalia clearly resemble birds in the quantity of air
which they consume. This difference in the extent of re-
spiration constitutes a remarkable distinction between the
vertebrata, and distributes them into four groups ; one in-
cluding reptiles and fishes, the other mammalia and birds.
This division is also founded on another characteristic,which
has given to the former the epithet of cold-blooded, and to
the latter that of warm-blooded ; a confirmation of the
* Prevost and Dumas have certainly given the best statement of the compara-
tive dimensions of the particles of the blood in different animals, but their views
as regards their form and structure are not confirmed by later observations made
under far more favourable circumstances as respects the instrument employed.
As far as the above remarks of Dr. Edwards are concerned, the correction is of no
importance. Some account of the physical constitution of the blood will be
found in the Appendix.
144 THE MODIFICATIONS OF RESPIRATION.
opinion that there exists an intimate connection between the
phenomena of the production of heat and the consumption
of air. The following; facts tend to the same conclusion.
Having ascertained that the mammalia which are born
with eyes closed, and the birds which are hatched without
feathers, bear a strong resemblance, in the early periods of
life, to cold-blooded vertebrata, in the phenomena of animal
heat, I was led by analogy to extend this resemblance to
the consumption of air. Experiment has confirmed this
opinion, and has shewn that the developement of heat in
mammalia and birds goes on increasing with the consump-
tion of air from birth to adult ao-e. Afterwards both these
functions undergo variations according to the influence of
the seasons. Those individuals which, by the successive
reduction of external temperature, acquire the faculty of
producing more heat, undergo, at the same time, a change
of constitution which occasions them to consume more air.
This is not the result of a difference in the rapidity of the
movements of respiration, nor of variations in the density of
the air, but of a change inherent in the animal economy.
The contrary effect is produced by the slow but progressive
elevation of the external temperature. There is a diminu-
tion in the production of heat, and also in the consumption
of air. These observations are only applicable to those indi-
viduals which, among warm-blooded animals including man,
support well the vicissitudes of heat and cold in the opposite
seasons of summer and winter. The other individuals which
we have pointed out as not seasoned to the climate, because
their production of heat diminishes by the influence of the
cold, would present the contrary phenomena. This is actually
the case with the hibernating mammalia. M. De Saissy
compared the respiration of the marmot, the hedgehog, the
dormouse, and the bat in the waking state, in August and
November. They consumed less air in the latter.
145
CHAPTER VIIL
OF THE COMBINED ACTION OF AIR AND TEMPERATURE,
It is easy, with some animals, greatly to vary their rela-
tions with the air, without destroying their life, provided
they are placed under favourable circumstances. We may
avail ourselves of this in examining the influence which
temperature exerts on life in those cases in which we vary
the extent of respiration. In the first part of this work,
many facts are stated upon which may be founded a
knowledge of this influence. I shall here briefly reca-
pitulate them, and add several others, that we may
judge of its generality. We have demonstrated that
several species of batrachian reptiles, such as the frog, the
toad, and the salamander, can live under water by means
of the air contained in it, and which acts solely on the
skin. There is then no pulmonary respiration. The
animal is reduced to cutaneous respiration, and even this
is at its minimum, because of the very small proportion of
air contained in the water. The air in this case must have
a very feeble vivifying power, yet it suffices to maintain
the life of the animal, so long as the temperature is be-
tween 0° cent, or 32° Fahr. and 10° cent, or 50° Fahr. ;
but if the temperature of the water be raised higher whilst
the animals are restricted to the same limited respiration,
the majority perish. To counteract the deleterious effects
of this low degree of warmth, their relation with the air
must be increased, its vivifying power will be augmented,
L
146
Or THE COMBINED ACTION OF
and life will be preserved. The animals cannot increase
their relation with the air except by coming to the surface
to exercise pulmonary respiration. It is by this means
that they preserve the equilibrium between the effects of
warmth and the influence of the air. When they are at
liberty in the marshes, pools, and small streams, they can
keep below the surface so long as the temperature of the
water does not exceed 10° cent, or 50° Fahr. as is generally
the case in autumn, winter, and the commencement of
spring, but however little it exceeds this point, they are
obliged to rise in order to draw air from the atmosphere.
Having received its vivifying influence by an increase of
respiration, they are again in a state to live under water,
and this for so much the longer time as the water is less
above 10° cent, or 50° Fahr., but in proportion as the tem-
perature is raised their tarriance under water is shortened,
and they come more and more frequently to the surface
until a point is arrived at, at which they can scarcely sup-
port the suspension of pulmonary respiration.
There is another mode of respiration to which these
animals are obliged to have recourse during the greatest
heat of summer. Pulmonary respiration aided by cuta-
neous respiration in water, is then unable to counteract the
effect of the high temperature. They are obliged to quit
the water to bring the skin into contact with the atmo-
sphere. Without this resource they would die in great
numbers. This is a necessary consequence of the relation
between the effect of heat and the influence of the atmo-
sphere. The following fact communicated to me by M.
Bosc confirms what I have advanced. In one of our re-
cent summers, remarkable for its long continued and in-
tense heat, many frogs died in a pool in his nursery. The
sides of the bason were too steep to allow of the frogs
coming out of the water, and during the great heat they
AIR AND TEMPERATURE. 147
were unable to counteract its influence either by cutaneous
respiration in air, or by the cooling power of evaporation.
The combined effects of temperature and air are the
same with fishes. Fish in winter can live under water
without coming to the surface to breathe. Different species,
according to their sensibility to heat, are obliged, as the
temperature rises in spring and summer, to increase their
relation with the air, by coming frequently to the surface,
to breathe the atmosphere. As this is generally the limit
of their respiration, they die in great numbers if the heat
of the season be intense. But those species which suffer
the least by evaporation in air, find the means of support-
ing this heat, by for a time exposing the skin and bronchiae
to the vivifying action of the air. Thus we may sometimes
see certain species keep in the shade, with the greater part
of their bodies out of water, resting on the leaves and
stalks of $he water-lilly, or quitting their own element to
throw themselves on the banks. They are then entirely
exposed to the action of the air, and breathe like land
animals.
The preceding cases are complicated with the substitu-
tion of another medium, the influence of which upon the
animal economy, may at equal temperatures be very dif-
ferent ; and in fact it is so, independently of the effect of
evaporation in air, but it will be seen, by the following ex-
periments in which this complication does not exist, that
this effect is only an accessory.
The batrachians can live in air with the action of the
lungs suppressed. It has been shown in a preceding
part of this work, that frogs deprived of their lungs have
survived a long time in air, by cutaneous respiration alone,
provided the necessary precautions are taken to preserve
their humidity. They live in this way in winter, and
when the temperature is low; but if the action of the lungs
l 2
148 OF THE COMBINED ACTION OF
is suppressed in this way in summer, they die almost as
quickly as when entirely deprived of the action of the
air by submersion in water. The vivifying action of the
atmosphere, on the skin is too feeble to counteract the
deleterious influence of the summer heat. Observe too
that they have the assistance of a more active evaporation
to cool them ; but this advantage is insufficient. It is
essential that they should increase their relation with the
air, by means of the lungs, in order to bear this high
temperature.
The same relation between the combined effects of heat
and air is observed when different means are employed to
limit respiration. A solid but porous envelop lessens the
contact with the air, yet frogs have lived for a considerable
time buried in plaster, (see Part I. Chap. 1.) Those expe-
riments were made in winter, and the animals bore this
limited respiration, because the temperature was low.
The case is different in summer ; I have then known them
die when similarly enclosed, almost as quickly as if they
had been plunged under water. If at this season sand be
used instead of plaster, they can live a much longer time,
because the sand admits more air.
There can be no doubt that the relation between heat
and respiration extends to warm-blooded animals. An
observation of Legallois furnishes a proof that it holds in
the case of young mammalia. The cutting of the eighth
pair of nerves produces, along with other phenomena, a
considerable diminution in the opening of the glottis, so
that in puppies recently born, or one or two days old, so
little air enters the lungs, that when the experiment is
made in ordinary circumstances, the animal perishes as
quickly as if it was entirely deprived of air ; it lives about
half an hour. But if the same operation be performed
upon puppies of the same age benumbed with cold, they
AIR AND TEMPERATURE. 149
will live a whole day, In the first case, the small quantity
of air is insufficient to counteract the effect of the heat, but
in the other it is sufficient to prolong life considerably.
We shall now apply this principle to adult age, and
particularly to man. A person is asphyxiated by an ex-
cessive quantity of carbonic acid, in the air which he
breathes ; the beating of the pulse is no longer sensible, the
respiratory movements are not seen, his temperature how-
ever is still elevated. How should we act, to recal life?
Although the action of the respiratory organs is no longer
visible, all communication with the air is not cut off. The
air is in contact with the skin, upon which it exerts a
vivifying influence ; it is also in contact with the lungs,
in which it is renewed by the agitation which is constantly
taking place in the atmosphere, and by the heat of the
body which rarifies it. The heart continues to beat, and
maintains a certain degree of circulation, although not
perceptible by the pulse. The temperature of the body is
too high to allow the feeble respiration to produce upon the
system all the effect of which it is susceptible. The tem-
perature must then be reduced, the patient must be with-
drawn from the deleterious atmosphere, stripped of his
clothes, that the air may have a more extended action
upon his skin, exposed to the cold, although it be winter,
and cold water thrown upon his face until the respiratory
movements reappear. This is precisely the treatment
adopted in practice to revive an individual in a state of
asphyxia. If instead of cold, continued warmth were to
be applied, it would be one of the most effectual means of
extinguishing life. This consequence like the former, is
confirmed by experience.
In sudden faintings, when the pulse is weak or imper-
ceptible, the action of the respiratory organs diminished,
and sensation and voluntary motion suspended, persons
150 OF THE COMBINED ACTION OF AIR, &C.
the most ignorant of medicine are aware that means of re-
frigeration must be employed, such as exposure to air,
ventilation, sprinkling with cold water. The efiicacy of
this plan of treatment is explained on the principle before
laid down.
Likewise in violent attacks of asthma, when the extent
of respiration is so reduced that the patient experiences
suffocation, he courts the cold even in the most severe
weather, he opens the windows, breathes a frosty air, and
finds himself relieved.
151
CHAPTER IX.
EFFECTS OF TEMPERATURE UPON THE FUNCTIONS OF
RESPIRATION AND CIRCULATION.
The organization of the vertebrated animals which breathe
in the atmosphere furnishes them with several means of
quickly modifying their communications with the air.
These consist principally, in the first place, in the move-
ments of the thorax and abdomen, and in the second place,
in those of the heart and blood-vessels. The former are
the movements concerned in respiration, the latter in cir-
culation. It is rare that one set is accelerated or retarded
without being accompanied by a corresponding change in
the other.
Every body knows that the will can retard, accelerate,
or stop the respiratory movements, but it rarely takes any
part in them. They are determined by another force which
keeps up and controls them. Throughout life they pro-
ceed, except under particular circumstances, without our
being conscious of them, and when the will occasionally
interferes, it only does so for a few moments. They habit-
ually proceed at a regular rate, the same number of move-
ments being produced in certain intervals.
This rhythm is maintained with very little variation so
long as the system and external circumstances remain the
same. This observation is applicable to all the vertebrata
which breathe air.
152 EFFECTS OF TEMPERATURE UPON THE
Let us study the relations according to which the
respiratory movements are affected by external tempe-
rature.
We know that elevation of temperature accelerates their
movements. It is a general phenomenon, but the degree of
temperature necessary to produce this effect is not the
same for all. From what has been already said, we may
comprehend the advantage of this acceleration, which rarely
takes place to a very sensible degree, except when the heat
is oppressive or very distressing. We then extend our re-
lations with the air, and increase its vivifying influence.
The respiratory movements become more rapid or more ex-
tensive, and thus more air comes in contact with the lungs
in a given time, and reanimates what the heat depresses.
From this increase of the respiratory movements necessary
to counteract, at least for a time, the effects of external
temperature, arises an order of phenomena different from
those of health, and which characterize a peculiar type
of fever.
There is a certain range of moderate temperature within
which the respiratory movements vary but little. This
range is of greater or less extent according to the constitu-
tion of the individual. We have shewn the effects of tem-
perature exceeding the superior limit ; we shall now pass
to the effects of temperature reduced below the inferior
limit. These effects are not, as in the preceding case, uni-
form in all the vertebrata. Cold, when it influences the
respiratory movements of reptiles, retards them progres-
sively, according to its intensity, until it arrests them.
Life then is ready to be extinguished. If, whilst respira-
tion is diminished by the cold, the heat of those animals
could maintain itself, life, with the greater part, would
soon be extinguished. But reptiles conform very closely
to the external temperature ; and the diminution of their
FUNCTIONS OF RESPIRATION AND CIRCULATION. 153
heat co-operates with that of their respiration for the pre-
servation of their life.
When the cold descends below the point at which respi-
ration ceases, it becomes destructive. To prevent death
without changing the external temperature, it is necessary
to increase the action of the air, which cannot be done but
by increasing the respiratory movements. Reptiles, how-
ever, do not appear to have such a resource in themselves,
though we shall see that there are animals which have.
Among mammalia, the hibernating animals present such
a series of phenomena. In spring and summer their tem-
perature is high and their respiratory movements lively, as
in other animals of their class ; in the decline of the year,
their temperature and motions are observed sensibly to di-
minish, provided the observations are made at sufficiently
long intervals. This simultaneous decrease may go on
until the cessation of the respiratory movements, without
putting a stop to life. But if the cold becomes more in-
tense, the animal must perish, or extend its relations with
the air. The intensity of the cold, under which it is ready
to sink, excites the respiratory movements ; the air inspired
maintains them, at least for a time, and counteracts the
destructive influence of the temperature.
Thus, cold may either retard or accelerate the respiratory
movements, according to its intensity and the constitution
of the animals. We have just seen that it is the most in-
tense cold which produces this last effect upon hibernating
mammalia.
However slightly the young of warm-blooded animals
may be exposed to cold, it accelerates the respiratory
movements or increases their extent. This phenomenon is
very remarkable in those which are born without the power
of maintaining their temperature in the open air. They,
but more especially young birds of this description, are no
154 EFFECTS OF TEMPERATURE UPON THE
sooner exposed to cold than their respiration increases in
rapidity or extent, and their temperature begins to fall.
No doubt they experience a lively sensation of cold, not-
withstanding the warmth of the season — their whole being-
indicates it. They present the phenomena of an attack
of febris algida, and this state is quickly fatal if not
remedied by renewing the heat of the body. Although
the acceleration of respiration is a powerful means of coun-
teracting the effects of cold, by extending the contact of
the air with the organs best adapted to feel its vivifying
influence, this acceleration has its limits ; it may diminish,
but cannot compensate for the effects of excessive cold.
In this case it retards, but does not prevent, death. In
other circumstances, when the cold is more moderate, this
vis conservatrix may prove effectual. The word cold is here
used in its strictest sense, but refers to temperatures to
which do not ordinarily suggest that idea. The words
heat and cold, as is well seen in this instance, are com-
pletely relative when applied to the animal economy.
Let us follow these young animals in the progress of life.
The same temperature less and less affects the respiratory
movements, until at length it has no influence over them :
consequently, in adult age, the rapidity of their movements
is much less subject to the influence of external tempera-
ture. But whatever be the extent of the range in which
the movements of the thorax preserve the characteristic
type of health, there is a degree of cold which alters them.
In all the experiments which I have made upon the refri-
geration of adult warm-blooded animals which are not sub-
ject to hibernation, I have remarked an acceleration of the
respiratory movements until, the powers being exhausted,
these movements, like all the others, languish and fail. I
do not doubt that there are cases in which an abatement
of respiration takes place with these as with the hi-
FUNCTIONS OF RESPIRATION AND CIRCULATION. 155
bernating mammalia, but we cannot now enter into this
enquiry.
We have said that there is a range of temperature within
which variations scarcely influence the rapidity of the re-
spiratory movements, and that this latitude is greater or
less according to the constitution of the animal. Now this
is a relation which it is of importance to understand with
the greatest possible precision, because, if we know the
kind of constitution which in the variations of external
temperature more or less preserves that rhythm of the re-
spiratory movements which characterizes health, we should
be better able to maintain it, or when it is deranged by this
cause, to re-establish it. We have seen that mammalia
and birds are more affected in this respect by external
temperature, in proportion to their youth. Now the most
important modifications of functions which characterize
the differences of age in the animals of these two classes,
are those of the production of heat and the extent of respi-
ration. It is with the development of these two functions
that we see a diminution of the influence of external tem-
perature upon the respiratory movements. This corre-
spondence exists even in those cases where there is no
difference of age. We may be convinced of this by com-
paring, at their birth, the mammalia which are born with
closed eyes to those which are born with their eyes open.
It is the same in adult age : thus the hibernating mam-
malia, which produce less heat and consume less air than
the other mammalia, experience a sensible alteration in
their respiratory movements, from a degree of cold which
would have no effect upon the rhythm of respiration in
others.
It follows from these facts, that when an individual ex-
periences a change of constitution which diminishes his
production of heat or consumption of air, he cannot endure
156 EFFECTS OF TEMPERATURE, &C.
that degree of cold which previously would have been salu-
tary to him, without experiencing sooner or later an altera-
tion in the rate of his respiratory movements. Hence
the necessity, when these two functions have experienced
this alteration, as in cases of organic affection of the heart
and lungs, of placing the patient in communication with a
milder temperature, either artificially or by change of
climate.
157
CHAPTER X.
INFLUENCE OF THE RESPIRATORY MOVEMENTS ON THE
PRODUCTION OF HEAT.
In studying the influence of the respiratory movements on
the production of heat, we must confine ourselves to the
mammalia and birds; because reptiles produce too little
heat to enable us easily to appreciate the causes which
modify it.
When we see the diminution of the temperature and of
the respiratory movements of hibernating animals take
place at the same time under the influence of cold, we can
draw no conclusion from it in reference to the subject be-
fore us, since the cold is the cause of both phenomena.
In like manner, when we remove one of those animals from
the place where he has been benumbed into a warmer situ-
ation, his respiration is accelerated, and his temperature
rises, under the same influence of external heat. But
there are other facts relative to those animals, in which we
recognize the influence of the respiratory movements in
the elevation of heat. I shall quote the experiments of M.
de Saissy.
The air of the room was 1° 5 cent, or 3° 7 Fahr. below
the freezing point. The temperature of a bat profoundly
torpid was at 4° cent, or 39° Fahr. M. de Saissy irritated
it by mechanical means, and left it exposed to the same
temperature at which it had become torpid. It was an
158 INFLUENCE OF THE RESPIRATORY MOVEMENTS
hour in awaking; thirty minutes after, its temperature was
15° cent, or 59° Fahr., and in thirty minutes more 27° cent,
or 80° 6 Fahr., but it could not pass this limit.
A hedge-hog, equally benumbed, in the same place was
only 3 cent, or 37° 4 Fahr. He was excited in the same
manner. lie did not awake for two hours. His tempera-
ture was then 12° 5 cent. 54° 5 Fahr. ; an hour after, 30°
cent. 86° Fahr. : it rose afterwards only 2° cent. 3° 6 Fahr.
in the same interval, and then remained stationary.
In the same circumstances, a dormouse cooled to the
same degree was stimulated in the same manner. In an
hour, its temperature was 25° cent. 77° Fahr., and in the
same space of time, the animal had recovered its natural
heat, 36° cent. 97° Fahr.
In these experiments, the external temperature had no-
thing to do with the restoration of the animal heat, and we
shall see by the following experiments of the same author
that the means of mechanical excitation had no perceptible
share in its production, except by exciting respiration and
circulation, thereby showing that the increased respiratory
movements and the restoration of heat stand related as
cause and effect.
On the same day and hour when M. de Saissy performed
the experiments above mentioned, he placed in a window
exposed to the north, with the precautions necessary not to
arouse them, another hedge-hog and dormouse, whose tem-
perature was 4° cent. 39° Fahr.,while that of the atmosphere
was 4° below zero cent. 25° Fahr. The respiratory move-
ments were very feeble. The dormouse awoke a little more
slowly than in the preceding experiment, and ran into his
cage with agility. In the first hour from his exposure to the
cold, his temperature, like that of the other dormouse, rose
to 25° cent. 77° Fahr., and at the end of the second, to
36° cent. 97° Fahr. The hedge-hog awoke two hours and
ON THE PRODUCTION OF HEAT. 159
a half after the commencement of the experiment, when his
heat had only risen to 12° cent. 54° Fahr. At the end of
five hours, it was 28° cent. 82° Fahr.
In this new set of experiments, it is evident that the
cause which produced the awakening was not of a nature
to contribute directly to the production of heat. If a mo-
derate cold may favour it, as we have shown elsewhere, a
more severe cold has a contrary tendency. In this instance
the intense cold produced an impression sufficiently power-
ful to be perceived in spite of the torpor, and excited to
more extended respiration.
We recognize in this chain of phenomena a striking ex-
ample of that vis conservatrix of which so much has been
said, and which in general has been perceived rather than
distinguished. We shall have on more than one occasion
to specify the means which nature employs to contend
against the agents which threaten life.
But the cause which has excited the movements of these
animals is not adequate to maintain them. They pro-
duce too little heat, even in expending all their resources,
to resist for any length of time the temperature which has
momentarily stimulated them. The cold which has roused
them withdraws too rapidly the heat springing up under
the influence of respiration and circulation, to allow the
play of these functions to continue ; their temperature
quickly sinks, and they relapse into a lethargy which be-
comes fatal from the intensity of the cold.
This is not the case when, in a moderate cold, they are
excited by mechanical means : after having recovered more
or less heat, according to their power of producing it, they
return to their original state, from which they may again
be excited.
In these observations on hibernating animals, the respi-
ratory movements, at first very feeble and scarcely percep-
160 INFLUENCE OF THE RESPIRATORY MOVEMENTS
tible, progressively increase to the degree of rapidity and
extent which they have in the natural state.* The ques-
tion now is, what is the influence of these movements on
the temperature of the body, when they are raised beyond
the rate of health ?
We cannot answer this enquiry by observations made
on the sick. The circumstances are then too complicated
to admit of even drawing conclusions from them : we must
seek our examples amongst healthy animals, whose consti-
tutions and the modifications which they undergo from the
circumstances in which they are placed, are not unknown
to us.
We have said that young birds collected in their nest
have a high temperature, although they have then few, if
any, feathers, but that their temperature falls as soon as
they are exposed to the air. In the first days after they
are hatched, their cooling in such a case is constantly pro-
gressive until the limit at which the cold benumbs them.
Whatever be the modifications of their respiratory move-
ments, this effect always takes place, and it is not at this
period that we can discern the influence of respiration upon
temperature : they then produce so little heat, that no ef-
fort of their organization can rescue them from the succes-
sive reduction of their temperature ; but some days later,
when they develope more heat, we frequently recognize by
unequivocal indications that the acceleration of respiration
beyond the rate of health is a salutary re-action to increase
the heat of the body, and counteract the influence of the
cooling process. The following experiments will show the
result of observations on several individuals very near the
age at which they can maintain their own temperature in
* The acceleration of the respiratory movements does not always stop at this
limit ; but in these irregular movements, we cannot distinguish the phenomenon
which we have next to examine.
ON THE PRODUCTION OF HEAT. 161
the air. One of them had a temperature of 40° cent.
104° Fahr. and 97 inspirations per minute. Taken from
the nest, and exposed to the air of the room, which was at
18° cent. 64° Fahr., he lost 3° cent. 5° 4 Fahr. in a quarter
of an hour : his respiration, however, had been accelerated.
They rose to 120 inspirations per minute, which rate was
maintained for twenty minutes. He was then warmed half
a degree ; some time after he cooled again, but his respira-
tion, which had become a little less frequent, acquired ex-
tension ; his heat was restored to the same degree, and
continued so for some time. Another had a temperature
of 38° cent. 66° Fahr. and 84 inspirations per minute ; a
quarter of an hour after his exposure to the air, he lost
three quarters of a degree cent. 1° 3 Fahr., his respiration
had risen to 108 inspirations, and continued at this rate;
examined at the end of an hour, he had recovered his ori-
ginal temperature. Lastly, in another, the respiration was
accelerated, and his temperature, instead of falling, rose
one degree.
Here, then, are several cases in which the acceleration of
respiration above the type of health may have a sensible ef-
fect upon animal heat. In the first, the temperature of the
body falls under the influence of the cooling cause ; but
by the re-action in question, it rises a little, without, how-
ever, being restored, and may afterwards fall lower, pre-
senting fluctuations. In the second it diminishes, and af-
terwards returns to the point of departure. Lastly, in the
third, it does not fall, and can not only support itself, but
even rise above what it was at first.
From the foregoing facts, it follows, that in the cases in
which the temperature of the body progressively falls, not-
withstanding the acceleration of respiration, the effect of
this acceleration is limited to a retardation of the cooling
process.
M
162
CHAPTER XL
ON PERSPIRATION.
Perspiration in the human subject has long been an
object of multiplied researches. Sanctorius was occupied
with it when experimental philosophy was yet in its in-
fancy. From the small quantity which sensibly escapes
in the form of sweat, no conception could be formed of the
considerable amount actually lost by perspiration in the
condition of imperceptible vapour. It was this quantity
which Sanctorius determined, and when he announced that
five-eighths of our ingesta escape in this form, he must
doubtless have excited either astonishment or incredulity.
He occupied himself during many years in determining,
by the help of scales, the variations in the quantity of per-
spired matter and the relations which they bear to the
food, the alvine and urinary evacuations and other percep-
tible secretions ; to the states of sleeping and waking, of
exercise and rest, of ease and of suffering, of sickness and
health ; to the passions, and to the periods of day and
night. These are relations which, with proper precautions,
he might determine with precision ; but from the state of
science at the time when he lived, he had not equal facili-
ties with respect to the action of external agents ; he has
therefore said little on the subject, and that little is either
vague or erroneous. It is more surprising that, as the in-
ventor of statical researches, he has furnished so few
ON PEKSPIRATION. 163
numerical reports, and still more wonderful that many of
his aphorisms are founded on reasoning rather than on the
use of the scales, even in those cases in which the informa-
tion could only be obtained by weighing. Sanctorius,
however, opened the path, and for this he deserves the tri-
bute of our gratitude. His successors have furnished more
positive data. Keill, Lining, Rye, Robinson, &c, have
published their results in the form of tables, the only sure
mode of enabling us justly to appreciate general proposi-
tions by shewing what is founded on fact and what merely
the produce of the imagination. All these labours princi-
pally relate to some of the subjects mentioned above, in
speaking of the researches of Sanctorius. Our object, on
the other hand, has been to examine the influence of most
of the external agents on the perspiration of vertebrated
animals. We shall apply to man the general facts which
result from these experiments ; we shall compare them with
the statements of those who have been engaged in statical
researches on perspiration ; and we shall enter into the de-
velopment of several points which we have reserved for
this (the fourth) part. We found it necessary to begin by
determining the rate of perspiration in equal and successive
periods, first examining them from hour to hour, whilst ex-
ternal circumstances continued sensibly the same. It was
shown by experiments on both cold and warm blooded
vertebrata, that the losses varied considerably from hour to
hour. The statical experimenters have paid little atten-
tion to this subject, but the fact is supported by the fol-
lowing remark of Sanctorius, " Non qualibet hora corpus
eodem modo perspirat."
We have seen, that with the inferior animals this fluctu-
ation disappears when longer intervals of time are em-
ployed, and that a successive diminution of the loss by
perspiration takes place at intervals of two, six, or nine
m 2
164 ON PERSPIRATION.
hours. If a diminution is effected in the shorter interval,
a fortiori it must take place in the longer. The average of
six hours will include almost all cases. The uniformity of
this phenomenon in the vertebrata is a sufficient ground
for admitting it in man, even though no observations had
been made on this point.
Thus, taking man, on getting up, in the state of health,
and in circumstances exercising no sensible influence on
his perspiration, whatever may be the fluctuations from
time to time, we may regard them as uniformly diminish-
ing in each succeeding period of six hours. In some it
may be presumed that longer periods will be necessary ;
nine hours ought to admit few exceptions. In some indi-
viduals again, successive diminution of perspiration may
be observed in periods of three hours ; this I should con-
sider as the minimum. We shall infer, from what has
been said, that the period of the greatest perspiration,
when no obstructing cause exists, is, in general, from the
hour of rising in the morning, say six o'clock, till noon,
and that the losses are successively less in similar intervals
for the remainder of the twenty-four hours.
To secure this regular course, it will readily be imagined
that it is necessary not only to remain quiet, but also to
abstain from food and sleep ; a condition which was pro-
bably not fulfilled by those who have hitherto made sta-
tical observations upon man. Nevertheless, it may be in-
ferred from these experiments that periods of six hours are
as applicable to men as to other animals.
Section I. — Influence of Meals.
The influence of meals requires particular examination,
the more so because it has rendered complicated the inves-
ON PERSPIRATION. 165
tigations of Sanctorius, Gorter, Keill, and others, as to the
period of most abundant perspiration. But for this com-
plication their results would, there is no doubt, have been
more accordant.
In taking food, new materials for perspiration are fur-
nished : but when does the food begin to have this effect
so as to augment the perspiration ? I shall propose ano-
ther question, which may appear strange to those who
have not had their attention turned to the subject. For
some hours after the meal, would not perspiration be di-
minished ? Sanctorius, in one of his axioms, has asserted
that perspiration is very slight for three hours after a meal,
but it is probable that the theoretical reason which he as-
signs for it, viz., that nature is too much occupied with
digestion to be engaged with perspiration, misled his judg-
ment, and induced him to generalize too hastily ; for we
may infer, from other parts of his work, that he had fre-
quently ascertained perspiration in such cases to be very
abundant. I shall content myself with a single aphorism,
Hord dormitionis meridiona. a cibo corpora aliquando libram
aliquando selibram excrementorum occulte perspirabilium ex-
cernere solent.
Keill, who has made comparative observations upon per-
spiration before and after dinner, has given us numerical
results, from which it appears that it was not less abundant
during the process of digestion. The experiments of Do-
dart and others confirm these conclusions, and even go
beyond them.
I do not, however, maintain that perspiration is necessa-
rily more abundant, but only that it is not necessarily di-
minished, and that if, as I have no doubt, it is sometimes
less at this period, it must be attributed to the fluctuation
which takes place when the periods of comparison are too
short.
166 ON PERSPIRATION.
There must, however, be limits within which we may
observe an increase of perspiration from the influence of
food. The following are the conditions necessary to render
the experiments comparative and the results conclusive :
1st. They ought to be made at the same hour, that the
system may be as much as possible in the same disposition
to perspire.
2dly. The space of time during which the perspiration
goes on ought to be sufficiently long to obviate the influ-
ence of the fluctuations so often referred to : it ought to be
six hours. These conditions appear sufficiently united in
the researches of Sanctorius to allow us to receive his data.
He expresses them in a general manner, in the 326th
aphorism : Qui vacuo ventriculo it cubitum, ea node tertiam
partem minus more solito cir titer per spir at.
We may be certain that this is not a hasty conclusion
from two small a number of experiments. He recurs to
the same subject in different places in which he gives the
quantities lost in both cases. The numbers and the pro-
portions differ, which evinces that he made repeated ex-
periments, and that the desire of uniformity did not in
this instance hurry him into premature generalization : in-
stead of a third, he frequently found more than twice that
difference.
In some instances the quantity lost by perspiration after
supper was not greater than when the individual retired
supperless. We must, however, conclude from the aver-
age, and remember that there are other causes which affect
the perspiration.
The night, in the researches of Sanctorius, is a period of
seven hours ; and as the increase of perspiration from the
influence of food was considerable, we may reduce to the
limit of six hours, the interval in which we shall recognize
ON PERSPIRATION. 167
this effect. We cannot appreciate this influence by ob-
serving the amount in similar periods before and after a meal.
Section II. — Influence of Sleep.
In order to judge of the influence of sleep we must com-
pare it with the state of watchfulness during the same
period.
It is only in Sanctorius and Keill that we find obser-
vations which can furnish data on this point. Both in-
form us in their aphorisms that perspiration is diminished
during restless nights spent in frequent tossing in bed.
It is evident that they compare a night of wakefulness
with a night of sleep. Sanctorius returns so frequently to
this subject, that he must frequently have observed the
relative influence of sleep and sleeplessness. We may
draw the same conclusion from the aphorisms in which he
speaks of perspiration during the day-sleep or siesta.
I have had sufficient occasion to observe this tendency of
sleep to increase perspiration, though I have not ascertained
it by statical experiment ; I have frequently observed upon
children of different ages, in good health, and fast asleep,
a degree of perspiration which astonished me when com-
pared with the temperature of the air or the thickness of
the bed-clothes. I am satisfied that it was not an acci-
dental effect, but an habitual tendency of sleep. We may
at any rate consider it as certain that perspiration during
sleep and in a state of health may be increased indepen-
dently of the action of external causes. It is necessary to
be aware of the natural variations in perspiration during
the twenty-four hours, and of the manner in which they
are influenced by food and sleep, in order to estimate the
power of other causes which operate on the perspiration.
168 ON PERSPIRATION.
Section III. — Influence of the Hygrometric State of the
Air.
In applying to man the results of the experiments made
on the vertebrata, we should say that the relative condi-
tions of dryness compared to extreme humidity, consider-
ably increases the perspiration within certain limits of
temperature. This qualification is indispensable to ren-
der the proposition correct. We shall afterwards see
the reason, and the facts upon which it rests. I may add
that the individual ought to be in health and in that ordi-
nary state of perspiration in which it is insensible ; in this
case, moderate degrees of dryness may render the losses of
weight by perspiration six or seven times greater than in
the cases of extreme humidity, and even go much farther.
The temperature at which these experiments were made
did not exceed 20° cent, or 68° Fahr. The greater amount
of perspiration in dry than in damp air does not take place
at all temperatures. The phenomena are reversed at a
high external temperature. We may see from this that
perspiration is a complex function, partly physical and
partly vital.
There is one circumstance accompanying the increase of
perspiration in dry air which deserves examination. It is
well known that evaporation cannot be increased without
producing cold ; all water which is converted into vapour
requires a certain quantity of heat proportionate to the
quantity evaporated. We learn that cold tends to dimi-
nish the loss occasioned by perspiration. Now, notwith-
standing the refrigeration caused by evaporation, the losses
by perspiration do not fail, with the qualification respecting
external temperature above referred to, to be greater in
dry than in damp air. The authors who have made re-
ON PERSPIRATION 169
searches respecting the perspiration of man have no diffi-
culty in admitting that it is increased by the dryness of
the air ; notwithstanding the complication of circumstances
in which their observations have been made, they have re-
cognised this effect.
Section IV. — Influence of the Motion and Rest of the
Air.
Gorter, although he has paid more attention than other
observers to the hygrometric state of the air, and has at-
tributed the increase of perspiration in dry air to increased
evaporation, has by no means fully appreciated the power
of this cause. Where the states of motion and rest are
concerned, he only considers the cooling effect produced
by the successive changes of the air heated by the body,
and concurs with the aphorisms of Sanctorius respecting
the diminution of perspiration by the movement of the air.
This is evidently not the result of experiment but of erro-
neous reasoning. The atmosphere which surrounds the
body is not only warm, but humid. That which replaces
it is colder, but at the same time drier. It is well known
that a current of air, independently of any other difference,
may in proportion to its rapidity produce an almost indefi-
nite increase in evaporation.
In other parts of this work, it has been established, by
direct experiments, that the motion of the air uniformly tends
to increase insensible perspiration. This cause is so power-
ful, that differences in the motion of the air, which appear
very slight, and which are sometimes imperceptible, occa-
sion very great differences in the losses from perspiration ;
so much do the physical conditions under which evapora-
tion takes place, influence the results of that function.
170 ON PERSPIRATION.
We have examined two of them, the hygrometric state,
and the motion of the air. It is necessary here to re-
collect, that this effect of the motion of the air is appli-
cable only to those circumstances in which there is not a
marked tendency to sensible perspiration or sweat.
Section V. — Influence of Atmospheric Pressure.
On this subject previous observers have left us nothing
but conjecture. Sanctorius, although the contemporary of
Galileo, the discoverer of the weight of the atmosphere, had
not the instruments necessary for this kind of observation.
Keill, although he carefully noted the state of the barome-
ter during his observations could discover no relation be-
tween the losses by perspiration and the changes in the
pressure of the atmosphere.
It is only within a short period that natural philosophers
have succeeded in determining the influence of the weight
of the atmosphere upon evaporation. They have taught
us that the diminution of pressure upon liquids accelerates
their conversion into vapour. After all the proof that we
have adduced of the influence exercised by physical causes
of this kind upon perspiration, we could scarcely doubt
that those which we have just mentioned act in like man-
ner on the animal economy. I have, however, attempted
to ascertain this by direct proof. I have compared the
perspiration of animals placed under the receiver of an air-
pump, containing rarefied air with that of individuals of
the same species exposed at the same time to the open air.
Cold-blooded animals are the best adapted for this kind of
experiments. They suffer little from the degree of rare-
faction to which the air must be reduced in order to ob-
tain quick and sensible effects ; the causes of complication
ON PERSPIRATION. 171
which would throw a doubt over the results of such expe-
riments upon warm-blooded animals, are thus excluded,
and it is found that in air which has been rarefied, the
losses by perspiration are increased. These experiments
are detailed in the first chapter of this work, and I have
no hesitation in applying the result to warm-blooded ani-
mals, including man.
Section VI. — Perspiration by Evaporation and by Trans-
udation.
There are three conditions which have a notable influ-
ence upon perspiration, viz. the hygrometric state, the
motion, and the pressure of the atmosphere. They act
only upon the insensible perspiration ; it is that which is
increased by the dryness, the agitation, and the rarefaction
of the atmosphere. These causes do not produce sweat,
at least directly, and the reason is evident, because they
act in a physical manner, they diminish the mass of li-
quids by causing a part to be converted into vapour. Sweat,
on the contrary, is a loss ordinarily produced by a vital
action, in the form of a liquid which transudes. This
leads us to distinguish two modes of perspiration, one by
evaporation, and the other by transudation. They would
appear at first synonymous with insensible perspiration and
sweat; but these terms, although they can sometimes be
substituted for each other, are not synonymous. The dis-
tinction is easy ; all that is lost by insensible perspiration
ought not to be considered as the result of perspiration by
evaporation. Is not the skin an excretory organ capable
of eliminating from the body a certain quantity of liquid,
independently of the co-operation of external agents, in
like manner as the urinary organs separate and reject a
part of the materials of the blood ? All that the skin
172 ON TERSPIRATION.
loses in virtue of this power is by transudation. The
quantity of liquid which issues in this way may be so
small, or if abundant may be so rapidly dissipated in va-
pour as to be insensible, and we commonly give the name
of sweat only to visible transudation. We may on the
other hand apply this term to the product of perspiration
by evaporation, when from any cause it happens to be con-
densed and precipitated upon the skin in the form of a
liquid.
All losses by perspiration are referable to these two modes
of action. They belong either to evaporation which is a
physical process, or to transudation, which is most fre-
quently a vital action.
Perspiration by evaporation takes place in the dead as
well as the living body. It is independent of every species
of transudation. It is a consequence of that porosity of
organized bodies, by which the liquids near surfaces in
contact with the air would diminish in quantity by being
converted into vapour, even though the pores should be
such as not to give passage to a single drop of liquid ; but
living bodies have the power of eliminating by their ex-
ternal surface a certain quantity of liquid ; a function
which appears to be always in operation, although vary-
ing in activity, which may be modified by external agents,
but which essentially depends upon causes inherent in the
living economy : it is in this view only that perspiration is
a secretion resembling the other secretions of the body.
We have already said that if this secretion did not exist,
perspiration by evaporation would notwithstanding go for-
ward ; on the other hand transudation takes place inde-
pendently of the other mode of perspiration.
As they are ordinarily combined, it would be interesting
to determine their relative shares ; we should then know
what we owe to physical processes and what we owe to
ON PERSPIRATION. 173
vital functions. Nothing appears easier in theory than to
establish this distinction. We have only to suppress the
physical conditions which permit evaporation, and if losses
are still produced by perspiration they will proceed from
transudation. We should then obtain the proportion
under given conditions, between perspiration by evapora-
tion and that by transudation. But in order to render
this method applicable we must pay attention to the fol-
lowing considerations.
Observe that, wholly to suppress perspiration by evapo-
ration, the air must not only be of extreme humidity, but
also at a temperature not inferior to that of the animal. If
the air were colder it would be warmed by the contact of
the body, it would then cease to be at its extreme of hu-
midity, and would permit an evaporation proportionate to
the degree to which it had been warmed. By making use
of the cold-blooded vertebrata, we may almost entirely sup-
press the loss by evaporation. Their temperature is not, as
is generally imagined, always superior to that of the at-
mosphere ; it is sometimes even lower ; and when it does
rise above it, it is usually only to a fraction of a degree,
and never more than one or two degrees (centigrade.) The
average of the differences is a little above the temperature
of the atmosphere, but this is so trifling that it may be dis-
regarded altogether.
In order to find the relative proportions of the losses by
transudation and evaporation in dry air, we must subtract
from the total that portion which has been incurred in hu-
mid air. It appeared from numerous experiments with
several species of cold-blooded vertebrata, that the propor-
tion in these modifications of the air is, in the generality of
cases, as seven to one.
Since the second term represents the quantity lost by
transudation, if it be subtracted from the first, the re-
174 ON PERSPIRATION.
mainder is equal to the loss by evaporation. Perspiration
by evaporation is then, in these cases, to that by transuda-
tion, as six to one.
By a series of experiments and inductions we have now
been enabled to determine that in ordinary circumstances,
in which perspiration is insensible, the losses by transu-
dation form but a small portion of the whole. This serves
to explain a great number of phenomena. We can thus
conceive how the physical conditions which are favourable
to evaporation, notwithstanding the diminution of transu-
dation occasioned by the cold which they produce, do not
fail, in ordinary circumstances, to increase the total loss.
We may also imagine how much the continual variation
in the motion of the air must contribute to produce these
variations of perspiration which we have observed to take
place with cold-blooded animals in successive intervals of
an hour.
All that we have hitherto shewn on the subject of per-
spiration will considerably facilitate our examination of a
question which naturally presents itself. Is perspiration
susceptible of being suppressed? It is easier to resolve
this question with regard to man and other warm-blooded
animals, than with respect to the cold-blooded vertebra ta.
Let us see what is the result of a very low temperature
upon warm-blooded animals. We know, by the effect of
cold upon the sweat, that it diminishes transudation. Now
let us suppose that it may, by its intensity, suppress it al-
together, there will remain perspiration by evaporation,
which will always take place however humid the air may
be. The high temperature of man and other warm-blooded
animals, warms the air in contact with the body, and
changes its hygrometric state by removing it from its ex-
treme of humidity, and consequently occasions evapora-
tion. If, on the other hand, the temperature of the air
ON PERSPIRATION. 175
be raised to an equality with that of the body, at the time
that it is saturated with humidity in order to suppress eva-
poration, then perspiration by transudation is excited,
and takes place to such an extent in man and other warm-
blooded animals, that the sweat will stream from all parts
of the body. We can then in no case suppress their per-
spiration ; it will be performed either by evaporation or by
transudation. We ought therefore to be careful how we
take literally what we find in medical books respecting
suppressed perspiration. There can be no such thing.
That there may be suppression of sweat, is evident to every
one ; but it does not follow that even in these cases there
is no transudation.
Since it is difficult to assure ourselves directly whether
transudation is ever entirely suppressed in man and other
warm-blooded animals, let us see what the cold-blooded
vertebrata will offer on this point.
The batrachians are the best adapted to this kind of re-
searches, on account of the nakedness of their skin, of the
fineness of its texture, of the copious loss which may be
incurred through its medium, and consequently of the re-
lation which their perspiration bears to that of man.
On exposing frogs to the temperature of 0° cent. 32°
Fahr. in humid air, in order to suppress perspiration by
evaporation, they have lost by transudation, in different
experiments, the 30th part of their weight. Transuda-
tion is more abundant in these animals than in man, though
the latter be placed in circumstanees much more favourable.
When we consider how sensible these creatures are to cold,
how much the activity of all their functions is diminished
at a low temperature, and how much they may even then
lose by transudation, it is not to be supposed that cold
suppresses this mode of perspiration in man, and the less
so from his having a temperature of his own which varies
176 ON PERSPIRATION.
very little with the changes of the atmosphere, a condition
which has a powerful tendency to maintain transudation.
It may be very much diminished by the action of cold, but
it appears that it cannot be altogether suppressed.
It is a remarkable, but well known fact, that when life
is sinking, and to appearance nearly extinct, the body is
covered with sweat — so strong is the tendency to continue
this function.
Since we can scarcely determine by direct experiment on
man and other warm-blooded animals the variations in the
amount of transudation at temperatures below that of the
body, because the losses by this mode of perspiration are
confounded with those by evaporation, we must have re-
course to the indirect means which have already served us
under similar circumstances.
Section VII. — On the Influence of Temperature.
In studying the influence of temperature upon the trans-
udation of batrachians at different degrees from 0° to 40°
cent. 32° to 104° Fahr. in air saturated with humidity, in
order to suppress perspiration by evaporation, we have ob-
served that the increase of loss by transudation between
0° and 10° 32° and 50° Fahr. was very slight ; that it was
similar between 10 and 20° cent. 50° and 68° Fahr. but
that at 40° cent. 104° Fahr. the increase was considerable ;
that on comparing the total of the losses in the space of
six hours at the temperature of 0° cent. 32° Fahr. and
that which took place at 40° cent. 104° Fahr. they were
nearly as 1 to 55.
By raising the temperature of the humid air to 40° cent-
104° Fahr. we may occasion as great loss from transuda-
tion, as that which results from perspiration by evapora-
ON PERSPIRATION. 177
tion solely in a dry atmosphere at a temperature not ex-
ceeding 20° cent. 38° Fahr.
What inference can we draw from these facts relating
to cold-blooded animals which will be applicable to man
and other warm-blooded animals? It is probable from
what has just been shewn, that transudation in them,
undergoes but a slight increase from elevations of tempe-
rature to different degrees between 0° and 20° cent. 32°
and 68° Fahr. If we endeavour to verify this application
by the indications which simple observation furnishes, in
the impossibility of exact appreciation we shall find this
presumption confirmed. Every one has had occasion to
observe that between the limits of temperature which we
have mentioned, sweat is scarcely observable in man, when
he is at rest, is in perfect health, and is free from all agi-
tation of mind ; but when the temperature rises only 5° or
6° cent. 9° or 10° Fahr. above this limit, transudation be-
comes evident on a great number of persons in the most
tranquil state of body and mind, provided that the air be
neither too dry nor too agitated. However little the tem-
perature may be raised, the sweat increases in a proportion
which appears much greater than that of the increase of
temperature. There will then be a degree at which the
loss by transudation may equal that resulting from per-
spiration by evaporation in a very dry air, at or below 20°
cent. 68° Fahr.
Let us follow the modification of perspiration in an at-
mosphere of a progressively rising temperature. Two ef-
fects would result, which we shall now compare. The in-
crease of heat above 20° cent. 68° Fahr. would increase
transudation rapidly ; on the other hand the air becoming-
warmer, would increase evaporation in an increasing pro-
gression ; but the perspiration by evaporation would not
necessarily follow the same rate ; and for this reason : ac-
N
178 ON PERSPIRATION.
cording as the sweat becomes abundant, it spreads over
the body, and forms there an external layer more or less
extended. In this space in which the sweat intercepts the
contact of air with the skin, there is no perspiration by
evaporation ; there is evaporation at the expence of the layer
of sweat always supplied by transudation, but from these
parts no fluid evaporates from within through the pores,
and so far no perspiration by evaporation. This suppression
will be general when the sweat universally covers the skin.
Evaporation will always take place, but it will not be by
perspiration. In order that this progressive diminution of
perspiration by evaporation should take place in a dry air
of a rising temperature, it is evident that the atmosphere
ought to be calm or but little agitated ; for the motion of
the air, in proportion to its rapidity, increases evaporation
almost indefinitely ; whence it follows that sweat may be
so quickly taken off in an atmosphere which is dry, warm,
and sufficiently agitated, that the two modes of perspira-
tion, by evaporation and by transudation, may take place
at the same time as they do at lower temperatures.
Section VIII. — Cutaneous and Pulmonary Perspiration.
Sanctorius and Gorter were not ignorant of the pulmo-
nary perspiration, but the means which they employed to
estimate it were so imperfect that it would be useless to
give their results. Hales employed more exact processes,
but we shall pass them over and proceed to a period at
which chemistry and experimental philosophy were much
further advanced.
Lavoisier and Seguin estimated the average loss by per-
spiration from the skin and lungs in twenty-four hours, at
2 lbs. 13 ounces, of which 1 lb. 14 ounces is dissipated by
ON PEKSPJRATloN. 179
the skin, and 15 ounces by the lungs, which gives the pro-
portion of two to one.#
Of this loss a portion is owing to the evaporation of
water from the lungs, and another to the chemical changes
of the air in respiration ; but it is certain that the water is
the predominant portion. The difference in the manner in
which this fluid is dissipated by the lungs and by the skin
deserves particular attention.
Whatever transudation there may be within the lungs,
no liquid can issue from them but in the form of vapour.
A new portion of air enters at each inspiration ; it becomes
warm, and remains there until the whole mass rises nearly
to the temperature of the body : in virtue of this acquired
elevation, whatever may have been its previous hygrome-
tric state, it converts into vapour the liquid with which it
is in contact, and in respiration carries it into the atmo-
sphere. It brings with it no water in a liquid state, nor
any other substance in this form. There is then no loss
by pulmonary transudation. All the perspiration, as far
as water is concerned, takes place by evaporation ; making
a considerable difference between the lungs and the skin,
where the two modes of perspiration are united. This de-
pends on their structure, one of their organs being a cavity
which does not permit the flowing out of a liquid ; the other
a surface so disposed, as to allow its escape at all parts.
Here then is one reason for which, in man, the losses by
cutaneous perspiration are more abundant than those oc-
casioned by pulmonary perspiration. From this double
source of perspiration at the skin, it is subject, as we have
shewn, to great variations. From its greater simplicity,
the pulmonary perspiration is much more regular, and con-
sequently the losses are much more nearly equal in differ-
ent periods. However, the loss of water by the lungs is
See Lavoisier's Traite elementaire de Chimie, 3d edit. p. 228.
N 2
180 ON PERSPIRATION.
capable of being suppressed, because, being performed by
a physical process, it may be stopped by the physical con-
ditions which prevent evaporation. In an atmosphei'e sa-
turated with moisture, if the temperature were equal to or
above that of the body, there would be no watery perspi-
ration from the lungs, because there would be no evapora-
tions ; whilst the cutaneous perspiration would take place,
not by evaporation, but by transudation, and that to a very
large amount.
Section IX. — Perspiration in Water.
Supposing that water, in contact with the skin, had no
physiological action upon that organ, it would merely pre-
vent the contact of the air, and consequently suppress per-
spiration by evaporation from the skin. There would then
remain the loss by cutaneous transudation, which must
be added to that which takes place by the lungs.
181
CHAPTER XII.
ABSORPTION IN WATER.
We have hitherto proceeded on the supposition that water
exerted no special influence on the skin, and that it only
acted by intercepting the contact of the air. We shall now
enquire whether the presence of water produces any other
effects which complicate the results. Does any absorption
take place when water is in contact with the human skin ?
Seguin,* after examining the changes in the weight of the
body, both immersed in water and out of it, was induced to
reject the idea of absorption. The result of these experi-
ments may, however, admit of being differently viewed.
We have proved in that part of this work which treats of
the cold-blooded vertebrata, that the batrachians, whether
smooth like the frog, or thick and rough like the toad, are
capable of absorbing much water by their external surface,
and that the quantity absorbed not merely soaks into the tis-
sue of the skin, but spreads through the system, and is distri-
buted to the different parts. These animals, like man, have
the skin naked ; a condition the most favourable to absorp-
tion. It is true that the skin of man, from the nature of
its epidermis, is less disposed to absorption ; it nevertheless
possesses this property to a very great degree. We cannot
doubt it, when we observe what takes place in animals,
* See Memoires sur les Vaisseaux Absorbans, <Sfc. Annalesde Chimie, torn. xc.
182 ABSORPTION IN WATER.
whose integuments appear less fitted for giving passage to
water. I shall not speak of scaly fishes in which I have
proved absorption by the external surface, because in them
it might be attributed to the fins, the membranes of which
are extremely delicate, but I shall relate some facts re-
specting lizards, which I have not yet brought forward.
Their skin being entirely scaly would appear to offer an
insurmountable obstacle to absorption, yet I suspected that
this might not be the case. A lizard was exposed to the
open air in order to remove it from the point of saturation
and cause a sensible loss of weight. Perspiration in these
animals being very slight, several days were allowed. It
was then introduced into a tube and fastened by a fore and
a hind foot. I then placed it in water so as to immerse
only the tail, the hind legs and the hinder part of the trunk.
It was afterwards weighed at distant intervals and found
to have successively increased in weight, until it had sup-
plied the loss incurred by perspiration in the air. The ex-
periment was then stopped. This absorption was not mere
imbibition limited to the surface ; the water penetrated
deeper, and was distributed through the system. The body
and the limbs had resumed their roundness and plumpness,
and life, which would, ere long, have been extinguished in
the air, as had happened to sevei*al other individuals, which
were exposed at the same time, was prolonged by the
liquid which absorption at the external surface had fur-
nished to repair the loss which had been sustained.
If the scaly skin of the lizard permits such an ab-
sorption, it is impossible not to attribute this property to
the skin of man.
The skin of man, when in contact with water, exercises
two opposed functions: transudation and absorption, and
according to the predominance of either of these above the
other, the weight of the body is diminished or increased, or
ABSORPTION IN WATER. 183
their proportion may be such as completely to balance
their effects.
If the diminution of the weight of a man plunged in a
bath be exactly equal to the loss incurred by pulmonary
perspiration, the absorption by the skin is equal to the
transudation by the same organ.
The proportion, as quoted in the former chapter, from
Lavoisier and Seguin, which pulmonary perspiration bears
to general perspiration in the air, is 6° to 18° ; in their
second Memoir on Perspiration (Annales de Chim. vol. xc.
p. 22.) they give it 7° to 18". In the first series of expe-
riments, in which Seguin compares the loss in water to
that in air, he finds the proportion 6° 5' to 17°. Hence it
follows, that the loss in the bath did not exceed the pul-
monary perspiration. No more is necessary to render this
case an example of absorption, since we do not find in it
the excess of loss which would result from cutaneous
transudation. Seguin, however, infers from it the absence
of both functions ; and this explanation will equally ac-
count for the result ; but his own researches oblige him to
admit transudation in water at higher temperatures, al-
though he maintains that between the degrees of 12° 5' and
22° 5' cent, and 54° 5' and 72° 5' Fahr. neither transudation
nor absorption takes place.
There are cases in which direct proof cannot be ob-
tained, and in no science does this happen so often as in
physiology. When man is concerned experiment is fre-
quently impossible. In other cases in which a trial may be
made the results are equivocal, because, as in the present
case, the facts may be explained by two hypotheses. We
must then have recourse to comparative physiology, and
select those animals which admit of decisive experiments,
and whose constitution will admit of our arguing a fortiori
with respect to man.
184 ABSORPTION IN WATER
Let us apply this to the present case.
If we observe animals much more sensible to cold than
man, and in which it enchains all the functions in a much
greater degree, and find that transpiration takes place in
water of a much lower temperature than that which has
been supposed to suppress it in man, can we be induced to
believe that it really is suppressed at the more elevated tem-
perature in man, in whom the function in question pos-
sesses considerable energy ?
It will be recollected that in the first part of this work,
we treated of the influence of temperature upon the transu-
dation and absorption of batrachians in water. It was there
shewn that even at the degree of cold at which water is
ready to freeze, these two functions do not cease, which is
rendered evident by the alternate diminution and increase
of their weight according as either function predominates.
It is known that cold of that degree has a most powerful
action on these animals, whose activity it diminishes consi-
derably, so that at a temperature a little lower they become
torpid. Since transudation is not suppressed in them, not-
withstanding the intensity of the cold, will it cease in man
in a bath of from 12° 5' to 22° cent, or from 32° 5' to 40°
Fahr. higher temperature ?
Two causes exert the principal influence upon these
functions ; the quantity of liquid contained in the body,
and the temperature of the water in which it is immersed.
The greater the fullness of the body the less is the absorp-
tion, and the lower the temperature of the water the less
the exudation. Now it so happens that the experiments
of Seguin were made when the water was at a temperature
intermediate between the extremes of zero, cent, or 32° Fahr.
at which the increase of weight in the batrachians, if they
are a little below saturation, predominates over the loss by
transudation, and of 30° cent, or 66° Fahr. at which the
ABSORPTION IN WATER. 185
latter predominates over the former, and when it was con-
sequently to be expected that the two influences would
approximate to an equality. But in order to secure an in-
crease of weight in man by immersion, not only must the
circumstances be such, that absorption may exceed transu-
dation, but also that the excess may be greater than all the
loss occasioned by pulmonary exhalation during the im-
mersion, which according to the average of Seguin's ex-
periments is seven grains per minute or six drachms an
hour. Such a result cannot be expected under ordinary
circumstances ; but we must not hence conclude that such
an increase is impossible and reject the assertion of Haller.
We have seen that the preponderance of absorption over
transudation depends not only on the temperature, but also
on the greater or less fullness of the body. If, therefore, the
body had previously undergone a considerable loss from
perspiration by evaporation, without repairing that loss, it
would perspire the less, and be in the condition the most
favourable to increase by absorption.
186
CHAPTER XIII.
ABSORPTION IN HUMID AIR.
We should not be warranted in concluding, that bodies so
impregnated with humidity as those of animals absorb
watery vapour from the atmosphere, from the mere fact of
their absorbing water when immersed in it. When im-
mersed in a liquid the pores will be penetrated by it, or
there will be an interchange with the fluids already con-
tained in them, in consequence of the movements which
take place in every medium. Animals, on acconnt of the
quantity of fluid which they contain, appear more likely to
impart humidity to the atmosphere than to receive it ; this
is peculiarly applicable to warm-blooded animals, because,
having a temperature usually much higher than that of the
atmosphere, the air in contact with their bodies is warmed,
and thereby becomes more susceptible of imbibing moisture.
This at least applies to aqueous vapour ; the case may be
different with other vapours, such as those which have an
affinity to water. However, it is certain that the hair, at
least, is hygrometric, even when on our bodies during life,
and hence a part of the vapour which it condenses must
necessarily be transmitted to the bulb, when absorption
will take place.
The difficulty of ascertaining by the weight of the body
the absorption of aqueous vapour is still greater than in
the question as to the absorption of liquid water. Scattered
ABSORPTION IN HUMID AIR. 187
facts favour the idea of absorption from the atmosphere, but
they are, in general, vague and inconclusive.
I cannot doubt, from the vast number of facts attesting
it, that perspiration by transudation is a constant pheno-
menon within the limits of temperature to which my expe-
riments applied. Now I have had occasion to observe that
frogs in an extremely humid atmosphere, for the space of
an hour, had neither gained nor lost weight ; an interval in
which I had always found that they sensibly lost by transu-
dation. Instead of concluding that transudation was sup-
pressed, I conceived that there had been an absorption of
watery vapour equivalent to the loss by transudation ; and
the analogy of this process with what I had shown re-
specting their functions in water, necessarily decided me.
But as these experiments were somewhat equivocal, it
was desirable that others less ambiguous in their results
should be attempted.
A ring adder (couluivre a collier) was placed in a vessel
containing air of extreme humidity. The animal was
weighed at different intervals, and found at first to have
lost weight ; but instead of continuing to do so, it after-
wards gained more than fifteen grains, not above what it had
weighed originally, but above the point of diminution at
which it had arrived.
It has been stated, that in this respect warm-blooded ani-
mals are less favourably circumstanced than the cold-
blooded, to absorb vapour from the atmosphere, but their
organization may compensate for this, or even go beyond
it. I cannot but regard the following result, as a proof of
the absorption of watery vapour by the mammalia. I com-
pared the loss of weight of several guinea-pigs in dry and in
humid air. From the nature of the apparatus I was unable
to estimate the loss by perspiration, otherwise than by sub-
tracting from the total loss that of the alvine and urinary
188 ABSORPTION IN HUMID AIR.
evacuations of similar animals in the open air; but in
comparison I found that the average of the evacuations ex-
ceeded the diminution of weight in the humid air. It ap-
peared, therefore, that the absorption of watery vapour had
supplied this difference, as well as the loss by transudation ;
for it is not to the absorption of a portion of the respired
air that this effect can be ascribed.
Now applying these results to the case of man, it can-
not, in the first place, be believed that man has not, like
them, the power of absorbing watery vapour, and that in
sufficient quantity to be rendered evident, either by the
weight of the body not losing in humid air, or even by its
gaining during some time.
Secondly, these cases must be rare, if compared with
those in which we observe a loss of weight by perspiration,
notwithstanding the humidity of the atmosphere.
If now we examine recorded facts, we shall find a con-
firmation of these conclusions.
Gorter has been quoted as furnishing facts in proof of
the absorption of aqueous vapour, but I can only find in his
work, facts which relate to the cloths. Keill, in one of his
aphorisms, says, " Qua in are sub vaporis speck circum-
volitant aqua particular a cute nostra attracts cum sanguine
commiscentur et corpus pondere augent." Without the facts
on which it is founded, we might call the correctness of
the aphorism in question, or be uncertain as to the precise
sense in which it is to be understood ; for Sanctorius and
Gorter sometimes speak of increase of weight to denote the
sensation of heaviness, and sometimes a loss of weight below
that which is customary, which is a relative increase.
There is, however, a statement of Keill, which contains
a fact. " 27 Decemb. hac nocte octodecim humoris
uncias ex aere ad se somnians (corpus) attraxit."
Whatever doubt may be felt regarding either the source
ABSORPTION IN HUMID AIR. 189
or the authenticity of this observation of Keill, it acquires
a high value when we combine it with another made by
Lining, so circumstantial as to carry conviction along with
it:
" The same day again, betwixt 2f and 5-| P. M. my
clothing being the same and having no exercise, I drank
betwixt 5 xxiii. and ^xxv. more of punch, and the air being-
cooled by the clouds overspreading the heavens, the quan-
tity of urine was greatly increased, amounting in these 2|
hours to 5 xxviii. f ; but the perspiration was so much di-
minished, that the quantity of humid particles attracted
by my skin exceeded the quantity perspired in these 2\
hours, by 5 viii. 4. Two more instances of this attraction you
have in the same table." — Philosophical Transactions,
vol. xlii. 1743, p. 496.
190
CHAPTER XIV.
ON TEMPERATURE.
Sect. 1. — On the Degree of Heat which Man and Animals
can endure.
Shortly after the invention of the thermometer, when
meteorological observations were few and incomplete, it was
not known that man and other warm-blooded animals could
support a temperature superior to that of their bodies.
Boerhaave, in reflecting on the use of air in respiration,
adopted the opinion, that the access of this fluid seemed
to cool the lungs, in which the blood underwent a fermenta-
tion, by which a considerable degree of heat was produced,
and he thought that life would be extinguished if the tem-
perature of the air were superior to that of the bodies of
animals. Some experiments, undertaken at his suggestion,
by Fahrenheit and Prevoost, seemed to confirm this
opinion.
It was generally received, until the observations of
Lining, at Charlestown, in 1748, of Adanson, during his
voyage to Senegal, and of Henry Ellis, when governor of
Georgia, in 1758, proved that the temperature in those
various climates was elevated some degrees above that of
man, and yet proved injurious to only a very small number
of individuals. But the most remarkable fact that has
been published on this subject, is that for which we are in-
ON TEMPERATURE. 191
debted to the observation of Tillet and Duhavnel, provided
that no objection can be made to their measure of the tem-
perature.
During their stay at Rochefaucault in Angoumois, in
1 760, a baker's daughter, in their presence, entered into an
oven, the temperature of which they estimated to be at
least 1 12° Reaumur, which is equal to 128° 75' cent, or 264°
Fahr. She remained about twelve minutes in this exces-
sive heat without being much incommoded by it. This ex-
periment was repeated several times, after their departure,
on another girl, with the same success.*
New researches and observations were afterwards made
by Dr. Fordyce, with Banks, Blagden, Solander, and
others, in 1775. An association of men so distinguished
by their learning and sagacity, who observed on their own
persons the effects of excessive heat, must necessarily have
given rise to very interesting results.f These experiments
were for the most part repeated by Dobson at Liverpool.^
This subject was not of a nature to be exhausted ; MM.
Delaroche and Berger took it up in 1806, and supplied
several deficiencies. §
The experiments of Delaroche and Berger apply not
only to man but to other animals, and as they are the most
numerous and varied, we shall begin with some of their
results.
1st. In dry air. Wishing to ascertain the effects of a dry
atmosphere at a temperature little above that of warm-
blooded animals, they raised it by means of an iron stove
* Mem.de l'Acad. des Sciences, 1764. p. 185.
t Philosophical Transactions for 1775. pp. Ill and 484.
X Idem, 1775. p. 463.
§ Exp. sur les effets qu'une forte chaleur produit sur l'economie, etc. Paris,
1806.
192 ON TEMPERATURE.
in a small apartment, to a temperature varying between
42° 5' and 45° cent, or 108° 5' and 1 12° Fahr. They ex-
posed to this heat different species of vertebrata, viz. a cat,
a rabbit, a pigeon, a yellow-hammer, and a large frog; the
greater number at first remained undisturbed, but in about
half-an-hour they became agitated and their respiration was
progressively accelerated for about three quarters of an
hour, until it became panting. There was then a remission
of the symptoms in almost all the animals. They remained
an hour and a half; when none of them came out in a
natural state, but in half an hour or an hour they appeared
perfectly recovered.
It would appear, from these experiments, that vertebrated
animals exposed to a dry and hot air of 45° cent, or 112°
Fahr. are near the limit at which they cannot long survive.
Indeed, the same individuals, after having sensibly re-
covered from the effects of the previous heat, were intro-
duced into a stove, the air of which, at first 56° 25' cent,
or 133° 25' Fahr., arose towards the conclusion of the ex-
periment to 65° cent, or 149° Fahr. All except the frog
perished at various periods, from 24 minutes to 1 hour and
55 minutes. Three other series of experiments on reptiles*
mammifera, and birds, made within nearly the same limits
of temperature, had the same effects.
I know no example of man having supported for a longer
time so intense a heat. However, there have been persons
exposed for a short time to a higher temperature of
the air. A young man, in Dobson's experiments, re-
mained for twenty minutes, without great inconvenience,
in a stove, the air of which was at 98° 88' cent, or 210°
Fahr. but his pulse, which commonly was at 75 per minute,
beat 1 64 in this hot air.
But even this is not the extreme limit. M. Berger sup-
ON TEMPERATURE. 193
ported for 7 minutes an atmosphere of the temperature
of 109°.48 cent, or 229°.06 Fahr.; and Blagden, that of
115°.55 to 127°.67 cent. 240° to 260° Fahr. for 8 minutes.
2. In watery vapour'. It is known that bodies of a dif-
ferent nature, but whose temperature is the same, do not
communicate by contact, the same quantity of heat in a
given time. Hitherto, however, the investigation of the
heating power has been confined to the gases which have
been examined, with this object in view, by Petit and Du-
long. We are ignorant not only of the amount of the dif-
ference between watery vapour and dry air, but even on
which side is the superiority. We should naturally infer
that the heating power of vesicular vapour is greater than
that of dry air, and that animals are consequently unable
to endure it at so high a temperature. This inference is
confirmed by experiment.
M. Delaroche could not support, above ten minutes and
a half, a vapour bath, which, at first, at 37°.5 cent, or 99°.5
Fahr. rose, in eight minutes, to 51°.25 cent, or 124°.25
Fahr. and afterwards fell one degree.
M. Berger was obliged in twelve minutes and a half to
come out of a vapour bath of which the temperature had
risen from 41°.25 cent, or 106°.25 Fahr. to 53°.75 cent, or
128°.75 Fahr. He was weak and tottered on his legs, and
was affected with vertigo. The weakness and thirst lasted
the remainder of the day.
These gentlemen, however, supported for a considerably
longer time, without much inconvenience, higher tempera-
tures in dry air.
The peculiar sensation which resulted from the impres-
sion of heat was much more lively in the vapour bath, it
was a sense of scalding. These experiments have been
cited, because they are comparative, but not as indicating
the extreme of heat, which man is capable of supporting in
o
194 ON TEMPERATURE,
the vapour bath for that space of time. Joseph Acerb?
relates, in his voyage to the North Cape, that the peasants
of Finland can remain for above half-an-hour in a vapour
bath, the temperature of which is raised to 70° or 75° cent,
or J 58° or 167° Fahr.
3. In liquid water. It is not necessary to make very
precise experiments in order to be convinced that a bath
of hot water, at the same elevated temperature as a vapour-
bath, would act much more powerfully on the animal
economy.
I have had occasion to observe in reptiles, the great dif-
ference in the action of liquid water and of steam, at the
same temperature. I have never seen batrachians which
could live above two minutes in water, at 40° cent, or 104°
Fahr. although I have taken the precaution of holding a
part of the head out of the water, to allow the pulmonary
respiration to continue ; whilst individuals of the same
species (frogs), have supported the heat of air charged with
vapour at the same temperature above five hours.
Lemonnier, being at Bareges, plunged into the hottest
spring, which was at 45° cent, or 113° Fahr. He could not
remain in it above eight minutes. Violent agitation and
giddiness forced him to come out.
In comparing the intensity of the action of the different
media, — dry air, vapour and liquid water, upon the animal
economy when raised by a high temperature, I have only
referred to the difference in their heating power. I do not,
however, exclude other causes, but propose to examine them
as facts arise which relate to them.
In giving the results of these experiments, I have men-
tioned some of the effects produced by excessive heat, such
as the acceleration of the pulse and respiration, and sensa-
tion of greater or less heat, and some other symptions con-
nected with the nervous system. There is one which I
ON TEMPERATURE, 195
have not mentioned which deserves separate consideration,
I mean the state of the temperature of the body and tran-
spiration.
Sect. 2. — On the Infiuence of Excessive Heat upon the
Temperature of the Body.
]. Man. The first observations on the permanence of the
temperature of the body, notwithstanding the changes of the
seasons and the difference of climates, brought to light a
very remarkable phenomenon.
At first these observations only related to ordinary varia-
tions of temperature within limits below the heat of the
human body. Dr. Franklin was, I believe, the first to no-
tice a fact which appeared more wonderful.
He observed, one day in summer, the temperature of the
air being 37°.77 cent, or 100° Fahr. that the temperature
of his own body was only 35°.55 cent, or 96° Fahr. Now
this fact is particularly worthy of attention, first, as proving
that warm-blooded animals have the power of maintaining
in themselves a temperature inferior to that of the atmo-
sphere, when the latter is above its ordinary limits ; and
secondly, the temperature of the Doctor's body being below
the average temperature of man, excludes the idea that it
had received any accession of temperature from the atmo-
sphere.
But the question remains, is any degree of external heat
capable of raising the bodily temperature of man and other
warm-blooded animals, and if so, to what limit can it
raise ?
Dr. Fordyce, and his coadjutors, observed that their
temperature could be raised two or three degrees of Fahr.,
o2
196 ON TEMPERATURE.
equivalent to about a degree or a degree and a half of the
centigrade thermometer.
The greatest elevations of the bodily temperature of man,
under the influence of external heat, have been observed
by Delaroche and Berger in their own persons. The tem-
perature of the former being 36°.56 cent, or 97°.8 Fahr.
rose 5° cent, or 9° Fahr. by his staying eight minutes in a
stove containing air at 80° cent, or 176° Fahr. Berger,
whose temperature was the same, received an accession of
4°.25 cent, or 7°.65 Fahr., after staying sixteen minutes
inthe same stove, at 87°.5 cent, or 189°.5 Fahr. ; but it
might be objected to the estimation of their bodily tem-
perature, that they were taken at the mouth in an atmo-
sphere much warmer, which might have contributed to
raise the thermometer, or it might have been the result of a
local heat.
To obtain a decision free from objection, Berger and
Delaroche placed themselves successively in a case, through
which they could pass their heads, and by means of linen
cloths surrounding this aperture and their necks, they in-
tercepted the passage of the steam. The temperature of
the mouth must then have been the result of the tempera-
ture of the other parts of the body. After staying seven-
teen minutes in this steam-bath, at a temperature from
37°.5 cent, or 99°.5 Fahr. to 48°.75 cent, or 119°.75 Fahr.
^he temperature of Delaroche increased 3°. 12 cent, or 5°. 6
Fahr. In the same apparatus, the steam being from 40°
cent, or 104° Fahr. to 41°.25 cent, or 106° Fahr. Berger 's
temperature rose 1°.87 cent, or 3°.36 Fahr. in fifteen mi-
nutes.
Of course, experiments upon man cannot be extended
far enough to ascertain what is the highest degree which
his temperature can attain under the influence of exces-
sive atmospheric heat.
ON TEMPERATURE. 197
2. Warm-blooded animals. In the before-mentioned
stove, Delaroche and Berger exposed various species of
mammalia and birds to different degrees of dry hot air, the
lowest 50° cent, or 122° Fahr. and the highest 93°.75 cent,
or 200°.75 Fahr. They left them there till they died.
Notwithstanding the diversity of species, and of classes,
and of the degrees of heat to which they were exposed,
they all acquired nearly the same increase of temperature,
the limits of the variation being from 6°.25 cent, or 11°.25
Fahr. to 7°.18 cent, or 12°.92 Fahr. The bodily tempe-
rature having been ascertained by a thermometer introduced .
far into the rectum, is free from the objections above stated.
When we consider the uniformity of the above results,
we may infer, generally, that man and warm-blooded ani-
mals, under the influence of excessive heat in a dry air,
could not, during life, experience a higher elevation of
bodily temperature than 7° cent, or 12*6 Fahr., or 8° cent,
or 14° Fahr.
3. Cold-blooded vertebrata. The temperature of these
animals differs no more than one or two degrees cent, from
the external air throughout the various seasons of the year,
and it is, therefore, to be expected that it would continue to
exhibit a similar conformity in higher degrees of heat. In
the experiments of Delaroche and Berger, the highest tem-
perature attained, at the period of death, by individuals of
this species placed in the stove, was 40°.93 cent, or 105°. 67
Fahr. which is within the limits of the bodily temperature
of warm-blooded animals.
198 ON TEMPERATURE.
Sect. 3. — Comparison of the Losses by Perspiration in Dry
Air, Humid Air, and Water, at Temperatures inferior to
that of the Body.
Were we to conclude solely from experiments made at
temperatures below that of warm-blooded animals, we
should regard it as certain, that the loss by perspiration must
be greater in dry than in humid air when both are raised
to the same degree of excessive temperature. We do not,
at first, see why it should not be so. This was the opinion
of Blagden, who, in the experiments undertaken by Dr.
Fordyce, having felt the effects of excessively hot air, both
dry and humid, could judge from observation. But he
did not have recourse to weighing. Delaroche and Ber-
ger did, and obtained decisive results.
According to their experiments, made in the stove, and
vapour-bath, already mentioned, air excessively hot, and
charged with extreme humidity, excited a more abundant
perspiration than dry air, at a higher temperature.
The cause of this difference between the results of tem-
peratures higher than that of the body, and those which
occur in temperatures inferior to it, may be conceived from
what has already been stated on the subject of perspiration
by evaporation, and that by transudation.
In the variations of temperature under 20° cent, or 68°
Fahr., and in the ordinary circumstances of health, &c.
transudation forms only a small part of the general per-
spiration, but it increases rapidly from the effect of heat in
higher temperatures. At an excessive degree of heat, trans-
udation increases so much as to cover the whole surface of
the skin ; there is then no more perspiration by evaporation
at this surface, it being only an evaporation of water already
eliminated from the economy. In this state of things per-
ON TEMPERATURE. 199
spiration by the skin is performed only by transudation,
whether in dry air, or in that which is charged with hu-
midity. Other circumstances then being equal as regards
the skin, that state of air which has the greater heating
power, will occasion the greater transudation. Now, as we
have formerly shown, vesicular vapour, which is that of
vapour-baths, has a greater heating power than dry air ;
whence we conclude, that the loss through the medium of
the skin will be greater in the vapour-bath than in dry air.
There yet remains the comparison of the loss by the means
of the lungs ; here the predominance is not on the side of
the vapour-bath. The loss, as far as water is concerned,
is none, because it cannot be evaporated in air of extreme
humidity and of a heat superior to that of the body ; but in
dry air of the same temperature, the evaporation from the
lungs may be considerable. We know, however, by ex-
periment, that the excess of transudation in air loaded with
vesicular vapour more than counterbalances the evaporation
from the lungs in dry air.
Another circumstance to be considered is the cooling-
influence of evaporation, which takes places in dry air
only, and hence a considerable diminution of transuda-
tion.
It is easy to foresee the effects of a water-bath of exces-
sive heat, compared to those of dry and humid air. For the
same reason that the loss by perspiration is greater in the
vapour-bath than in the dry air at an excessive heat, it will
be still greater in water of the same temperature ; for the
heating power of water is greater than either that of vesi-
cular vapour, or dry air of the same temperature. This
conclusion is confirmed by fact. Lemonnier, after staying
eight minutes in a water bath at 45° cent, or 113° Fahr«
lost twenty ounces, which is at least double that which De-
200 ON TEMPERATURE.
laroche and Berger lost at the same temperature in a vapour-
bath, and at a temperature of above 90° cent, or 194° Fahr.
in dry air.
Sect. 4.— On the Influence of Evaporation upon the Tem-
perature of the Body when exposed to an excessive Heat.
When Franklin had made experiments on the power of
evaporation in the cooling of liquids, he referred to the
same cause, the faculty which he attributed to animals of
maintaining the temperature of their bodies below that of
the air when its heat is excessive. This opinion received
some support from the experiments of Fordyce, who did
not, however, regard the cause in question as the only one.
The researches of Delaroche and Berger give a more accu-
rate idea of the influence of evaporation on the temperature
of the body when exposed to great heat.
One of those porous vessels, called by the Spaniards al-
carazaz, which are susceptible of evaporation from the
whole of their surface, was introduced by Delaroche and
Berger into a stove, with two moistened sponges and a
frog. The temperature of the vessel and of the sponges
had been previously raised to that of warm-blooded animals,
from 38°. 12 cent, or 100°.6 Fahr. to 40°.93 cent, or 105°.67
Fahr. The temperature of the stove varied between 52°.5
cent, or 126°.o Fahr. and 61°.25 cent, or 142°.25 Fahr.
In a quarter of an hour, the vessel, the two sponges, and
the animal, were nearly of the same temperature, not
exceeding the limit of that of warm-blooded animals. They
retained it pretty nearly two hours. This term is remark-
able. In order to arrive at it, the vessel and the sponges,
instead of being warmed, cooled about a degree; on the
contrary, the temperature of the frog, which was at first
ON TEMPERATURE. 201
21°.25 cent, or 70°.25 Fahr. rose to 37°. 18 cent, or 98°.9
Fahr. in the space of fifteen minutes, and remained station-
ary for the rest of the time, maintaining itself, like the alca-
razaz and the sponges, at from 15° cent, or 27° Fahr. to21°.5
cent, or 38°.7 Fahr. below that of the surrounding medium.
A greater difference is observed, according as the ex-
ternal temperature is higher, but at the same time, the
term at which that of evaporating bodies becomes nearly
stationary is a little higher, in conformity with this in-
crease of heat in the air.
If we suppose that as long as respiration is performed
by an animal, especially a warm-blooded animal, it pre-
serves the power of producing heat, a difference will thence
be inferred between its temperature and that of an inani-
mate body with an evaporating surface, exposed to an ex-
cessive heat, although their point of departure should be
the same. This conclusion is justified by the results of ex-
periments made by Delaroche and Berger. The evapora-
tion in a rabbit exposed to air from 62°.5 cent, or 144°.5
Fahr. to 87°.5 cent, or 189°.5 Fahr., judging by the di-
minution of its weight, was quite as great as that of the
alcarazaz ; the final temperature, however, of the rabbit
was superior by at least 2°. 5 cent, or 4°.5 Fahr.
Thus the same general cause, viz., evaporation, would
alone be sufficient to retain the temperature of animals and
inorganized bodies below that of the external air, when the
latter is excessive, that is, when it is above the bodily tem-
perature of warm-blooded animals ; but below this limit it
would be incorrect to attribute to this cause, as is gene-
rally done, the real or supposed power of man and other
warm-blooded animals, to maintain uniformity of tem-
perature under the vicissitudes of seasons and climates.
202 ON TEMPERATURE.
Sect. 5. — On Cooling in Different Media, at Temperatures,
inferior to that of the Body.
Let us now compare the power of cooling in the re-
spective media of dry air, vesicular vapour, and water at
temperatures inferior to that of the body. In the dry air,
less heat is taken off by contact, that is, its cooling power
is less, hence the heat will tend to accumulate in the body ;
but on the other hand, the evaporation being greater, there
will be in this respect a greater cooling effect than in the
vapour. The reverse will hold, in both respects, in ve-
sicular vapour. Thus, we see, in both instances, that at
inferior temperatures the two agents which influence the
heat of the body are opposed in their action, but we cannot
compare the result of their opposing powers, being ignorant
of the measure of each.
We cannot determine, a priori, in which the cooling effect
will preponderate.
The same applies to the comparision with water, and
our uncertainty is still greater in relation to air saturated
with transparent vapour; for experimental philosophers
are quite ignorant of the relative intensity of its cooling
power, and even whether it is greater or less than that of
air. It is to be hoped that they will, ere long, decide a
point not unimportant in physics, and certainly important
in physiology.
It is, nevertheless, a generally established opinion, that
we experience a greater cooling effect in humid than in dry
air. This is evidently founded on the sensation, and other
effects which it produces on the animal system. It might
from this be inferred, that the cooling power of evaporation
in dry air was more than equalled by that of the contact of
transparent vapour. But this method of judging is very
ON TEMPERATURE. 203
equivocal. Hence I was induced to attempt a mode of in-
vestigation that would admit of greater certainty.
We have formerly shewn that many warm-blooded ani-
mals at the period of their birth, and shortly after, have
not the power of maintaining their temperature when with-
drawn from their nest, and exposed separately to the airo
I availed myself of this circumstance in order to compare
the refrigeration undergone in dry and humid air. I em-
ployed large vessels similar in form and dimensions to those
which I had used in investigating the phenomena of per-
spiration. I preferred animals of very small size, that the
proportion of air might be greater, with a view to the in-
fluence which the alteration of this fluid by respiration
might exercise on the temperature of the animals.
Besides, the vessels, formed of large squares of glass con-
nected by their edges, allowed of a change of air through
the joints, but with sufficient slowness to permit the pro-
duction of the necessary changes in its hygrometric state.
The same animal was placed successively in the two condi-
tions of extreme dryness and extreme humidity, but at suffi-
cient intervals to prevent the previous refrigeration from in-
fluencing that which was to succeed it. Several animals
of different ages were made use of, each of which was
alternately placed in the two different conditions. It would
be tedious to enumerate all the precautions which were
taken to render the comparison fair ; one only may be men-
tioned, which was, that the interval between the compara-
tive experiments on the same individual was not allowed
to be more than a few hours, since even a day would be
sufficient sensibly to increase the production of heat, the
progress of which is very rapid at so early a period of life.
Ten experiments were made in dry air, and as many in
humid air, upon young sparrows. The average of refrige-
ration was 6°.o cent, or 11°.7 Fahr., for the drv air, and
204 OF TEMPERATURE.
7°.7 cent, or 12° Fahr. for the humid. Disregarding this
slight difference we may admit, as the general result of
these experiments, that the refrigeration was the same in
the dry air and in the humid ; whence it follows that the
cold produced by the greater evaporation in the dry air, was
balanced by the cold resulting from the contact of the hu-
mid air.
Such is the average result of these experiments, but in
examining each singly, we shall see that in some the re-
frigeration was exactly the same in both conditions, in
others it was greater in the humid air, in others, in the dry
air. It is to be observed, that the humid air was at its
maximum in almost all the cases, and differed very little
from it in the others ; that the degree of dryness of the dry
air varied in the different experiments, and that it is pre-
cisely in that of which the limits were from 55 to 44 of
the hygrometer of Saussure, that the superiority of refrige-
ration was decidedly on the side of the dry air.
Sect. 6. — On Refrigeration in Air at Rest, and in Air
in Motion.
In air at rest, at a temperature inferior to that of our
bodies, we lose heat in three ways, by evaporation, by
the contact of the air, and by radiation. Loss by radiation
would equally have taken place in vacuo, and appears not
to be influenced by the motion of the gas. Now let the
air 'be agitated, its radiation will not be affected; but the
change of the air considerably increases the quantity of
heat taken away by contact, and in a degree proportioned
to the rapidity of the current. To the greater loss of heat
by this action of the wind, we must add the refrigeration
produced by an increased evaporation, which also aug-
ON TEMPERATURE. 205
ments with the rapidity of the wind. It is to these two
causes combined, that we must attribute the strong feeling
of cold which we experience when no other change of the
state of the atmosphere occurs than in the rapidity of its
motion.
In the celebrated voyage of Captain Parry to the Artie
Regions, there was frequent occasion to remark the dif*
ference between the indications of the thermometer and
those drawn from the feelings of the voyagers. They bore
very easily a temperature of 17°.77 cent, below the freezing-
point (0° Fahr.) when they were walking in the open air
in calm weather. This was not the case if the air was
agitated ; however, the temperature always rose with the
wind, whatever might be its direction. They suffered
more cold in a breeze when the temperature was only 6°.66
cent, below 0° ( + 20° Fahr.) than at 17°.77 cent, below
0° (0° Fahr.) when the air was at rest. The second sur-
geon in the expedition, Alexander Fisher, who relates the
above facts, furnishes a more remarkable example of the
cold occasioned by wind. He informs us that the tempera-
ture being at 46°.ll cent, below 0° ( — 51° Fahr.) during
calm weather, they were no more inconvenienced by the
cold, than when the air was at 17°.77 cent. (0° Fahr.)
during a breeze.
CHAPTER XV.
ON THE INFLUENCE OF LIGHT UPON THE DEVELOP-
MENT OF THE BODY.
Has light, by which we see and are warmed, any other
effect on the animal economy? Its influence on inorganic
bodies and on vegetables, is unequivocal. The solar rays
produce in the mineral kingdom combinations, which can-
not be brought about at the same low temperature without
it. Unaided by the influence of light, plants would
scarcely produce any of the green matter (of Priestly), a
substance so generally diffused through the vegetable king-
dom, that it seems to be one of the essential productions of
this class. When we consider that without light, inde-
pendently of its heat, there would scarcely exist a trace of
vegetation, can we suppose that it is inert with respect to
animal life?
But when we cast our eyes on man, and the various
classes of inferior animals, we scarcely observe any other
sensible relations with light than those of vision, which give
the perception of colours, forms and distances. The brown
tinge observable upon persons who are much exposed to the
sun, as it scarcely occurs except on exposed parts, and does
not require a great intensity of heat, is justly attributed to
the peculiar action of light. To what are called coups de
soleil, the heat appears to contribute in a considerable de-
ON THE INFLUENCE OF LIGHT. 207
gree. They have been attributed to a concentration of the
solar rays, in consequence of a particular disposition of the
clouds giving them the faculty of acting as a lens : there is,
however, no occasion to have recourse to so bold a suppo-
sition. But if it be true that inflammation of the skin
comes on most frequently from the effect of a burning sun,
it is likewise true that it may be the effect of a somewhat
intense light. I have known persons who were subject to
that affection when they were in strong day-light, in cir-
cumstances in which the sun had little force ; which indi-
cates a great sensibility to the peculiar action of light. It
is to the combined action of light and heat, that the sudden
deaths of those who are long exposed to the sun in hot
weather, ought in general to be ascribed.
With respect to the impaired health of those who live in
the dark, as for example, in mines and prisons, it is obvious
that we cannot distinguish the effect of the privation of
light from that of many other deleterious causes which we
find united in those unhealthly situations.
I thought that I might perhaps find an example of the
effect of light, in the development of animals, that is to say,
in those changes of form which they undergo in the interval
between conception or fecudation and adult age. This pro-
cess, previously to birth, is generally carried on in the dark.
There are, however, animals, whose impregnated eggs are
hatched, notwithstanding their exposure to the rays of the
sun. Of this number are the batrachians. I wished to
determine what influence light, independently of heat,
might exert upon this kind of development. With this
view I placed some frogs' spawn in water, in a vessel, which
was rendered impermeable to light by dark paper. The
other vessel was transparent. They were exposed to the
same degree of temperature, but the transparent vessel re-
ceived the rays of the sun. The eggs exposed to light
208 INFLUENCE OF LIGHT ON THE
were developed in succession. Of those in the dark none
did well ; in some, however, I remarked unequivocal in-
dications of the transformation of the embryo.
But it is especially after birth that it is interesting to
determine the peculiar effect of light upon the development
of the body, because then almost all animals are more or
less exposed to it. Although all, in growing, change their
form and proportions, it is difficult to perceive and appre-
ciate correctly slight shades of modification. The choice
must, therefore, fall upon species among the vertebrata,
whose development presents precise and palpable differences.
These conditions are combined in the highest degree, in
the species made use of in the preceding experiments, and,
in fact, in the whole batrachian family. All, during the
first period, have the form, and even the mode of life, of
fishes. They have no limbs, but a tail and gills. In the
second period they are reptiles without a trace of re-
semblance to the exterior form of fishes ; four limbs, and
neither tails nor gills ; the metamorphosis is complete. It is
evident from the experiments on these animals detailed in
the second part of this work, that the absence of light does
not necessarily prevent the development in question, since
two tadpoles, out of twelve, in a tin box pierced with small
holes for the change of water, and placed at the depth of
several feet in the Seine, underwent the change of form,
which renders them reptiles. Let us remark, in the first
place, that these two individuals were transformed much
later than those which were exposed to light, and were at
liberty to rise to the surface of the water. To what was
this lateness, and also the continuance of the others in the
form of fishes to be attributed ? Was it to the want of light
or of pulmonary respiration, or to the combination of both ?
An attempt was made to determine the respective influ-
ence of these two causes, first, by putting tadpoles in two
TEMPERATURE OF THE BODY. 209
large vessels containing ten litres of water, both capable
of admitting light ; one of glass, but with a partition close
to the water, to prevent atmospheric respiration, the other
open to allow the animals to rise to the surface and breathe
the atmospheric air. Those who were deprived of respira-
tion were certainly later in transforming themselves than
the others, but this delay was so short that the influence
of the want of respiration appeared to be very slight. It
results from the comparison of this fact with the pre-
ceding, that the absence of light had the principal share
in retarding the transformation of the two tadpoles plunged
in water, and in the continuance of the form of all the
others. This conclusion was afterwards put to the test of
a counter-proof. The experiment was performed upon two
tadpoles of the rana obstetricans. Both were allowed to
breathe at the surface ; they were inclosed in vessels into
which the light did not penetrate ; a large number of others
were placed in transparent vessels. One of those which
were deprived of light arrived at complete development ;
but the other retained its original form, characteristic of
the first period, whilst all those which enjoyed the pre-
sence of the light underwent the change of form apper-
taining to the adult. It is here very important to ob-
serve, that this influence of darkness on the form does not
proceed from a decay of the individual. It appeared in
perfect health, and what is very remarkable, it attained to
a large size, which phenomenon I had also observed in the
untransformed tadpoles in the tin-box before mentioned.
At the commencement of the experiment they had almost
attained the size at which the transformation takes place.
Each was weighed before it was placed in the compart-
ment appropriated to it. Several in the course of the
experiment doubled and even tripled their weight. These
two series of experiments unite, therefore, in proving that
p
210 INFLUENCE OF THE ATMOSPHERE ON THE
the presence of solar light favours the development of form.
They also shew the distinction between this kind of growth
and that which consists in the increase of size.
We see then that the action of light tends to develope
the different parts of the body, in that just proportion
which characterizes the type of the species. This type is
well characterized, only in the adult. The deviations from
it are the more strongly marked the nearer the animal is
to the period of its birth. If, therefore, there were any
species existing in circumstances unfavourable to their fur-
ther development, they might possibly long subsist under
* a type very different from that which nature had designed
for them. The proteus anguiformis appears to be of this
number. The facts above mentioned tend to confirm this
opinion. The proteus anguiformis lives in the subterra-
neous waters of Carniola, where the absence of light unites
with the low temperature of those lakes, in preventing the
development of the peculiar form of the adult.
The principles which we have deduced from experiments
upon animals, lead us to the following considerations re-
specting man. Tn the climates in which nudity is not in-
compatible with health, the exposure of the whole surface
of the body to light will be very favourable to the regular
conformation of the body. This application is confirmed
by an observation of Alexander de Humboldt in his voy-
age to the equinoctial regions. Speaking of the Chaymas,
he says : " Both men and women are very muscular, their
forms are fleshy and rounded. It is needless to add that
I have not seen a single individual with a natural de-
formity. I can say the same of many thousands of Caribs,
Muyscas, and Mexican and Peruvian Indians, which we
have observed during five years. Deformities and de-
viations are exceedingly rare in certain races of men, espe-
cially those which have the skin strongly coloured."
TEMPERATURE OF THE BODY. 211
On the other hand we must also conclude that the want
of sufficient light must constitute one of the external causes
which produce these deviations of form in children affected
with scrofula, which conclusion is supported by the obser-
vation that this disease is most prevalent in poor children
living in confined and dark streets. We may from the
same principle infer that in cases where these deformities I
do not appear incurable, exposure to the sun, in the open \
air, is one of the means tending to restore a good conforma-
tion. It is true that the light which falls upon our clothes,
acts only by the heat which it occasions, but the exposed
parts receive the peculiar influence of the light. Among
these parts, we must certainly regard the eyes as not merely
designed to enable us to perceive colour, form and size.
Their exquisite sensibility to light, must render them pecu-
liarly adapted to transmit the influence of this agent through-
out the system, and we know that the impression, of even
a moderate light, upon these organs produces, in several
acute diseases, a general exacerbation of symptoms.
p 2
212
CHAPTER XVI.
ON THE ALTERATIONS IN THE AIR FROM RESPIRA-
TION.
Since the first experiments of Priestley and Lavoisier,
on the alterations produced in the air by respiration, phi-
losophers have agreed upon these two points only ; 1, The
disappearance of a portion of oxygen ; and 2, The produc-
tion of carbonic acid. On the questions, — what becomes
of the oxygen ? how is the carbonic acid formed ? what
proportion does the oxygen bear to the carbonic acid ?
what takes place with respect to azote ? and several others
connected with this subject, great difference of opinion
continues to exist. These differences induced me to re-
sume the subject. When the constituents of the atmo-
sphere were first discovered, their proportions were not
exactly determined. This deficiency was necessarily a
source of error in the results of experimenters, yet since
the analysis of the air has been more complete, these dis-
crepancies have not been removed. Another cause must
therefore be sought, either in the mode of conducting the
experiment, or in the animals operated upon. As to the
mode of experiment, it never strictly resembles natural
respiration in the open air. Either the rhythm of the
respiratory movements, or the purity of the air is changed.
ALTERATIONS IN THE AIR FROM RESPIRATION. 213
Hence the results are more or less doubtful in proportion
as the natural respiration has been little or much disturbed.
The differences, referrible to the animals, depend rather on
nature than on the experimenter. These have been the
most overlooked. With the exception of Spallanzani and
Humboldt, almost all experimenters have confined their
attention to the respiration of man and of two species of
mammalia, the guinea-pig and the mouse. Man presents
other difficulties besides those just stated. His lungs con-
tain a large quantity of air both before and after the ex-
periment. The appretiation of this is indispensable in
very many cases, but it is so uncertain, that the results
dependent upon it are perpetually the subject of doubt and
dispute. The experiments of Spallanzani embrace almost
the whole scale of animated beings. The extent and ge-
nerality of the results, and the sagacity and talent of their
author, were calculated to inspire great confidence, yet
they had little influence on the views of physiologists re-
specting the alteration of the air in respiration, either be-
cause the analysis of the atmosphere was in his time im-
perfect, or because his experiments were not made on man.
It must, however, be remarked that Humboldt, who with
Gay-Lussac, has contributed much to establish the exact
proportion of oxygen and azote, has proved, in his exten-
sive labours with Provencal respecting the respiration of
fishes, that that class of vertebrata change the air in the
same manner as Spallanzani had pointed out with respect
to the other vertebrata. About the same time Davy, whose
name marks an epoch in the history of chemistry and ex-
perimental philosophy, obtained similar results with man,
and on other species of mammalia. These successive re-
searches seemed to be decisive. Others were yet under-
taken by Allen and Pepys, who by the precautions which
214 ON THE ALTERATIONS IN THE
they adopted gave great weight to the results. According
to them, free natural respiration is reducible to two facts
already discovered, viz. the disappearance of a portion of
oxygen, and the production of an equivalent portion of car-
bonic acid. Respiration was thus reduced to great simpli-
city. The oxygen lost being exactly represented by the car-
bonic acid, its office appeared to be merely that of entering
the lungs to form a portion of carbon and be expelled. Hence
it might be argued that no oxygen is absorbed and carried
into the circulation, either to enter into new combinations
or to excite and vivify the ceconomy. The azote appeared
to pass for nothing in respiration. However accurate
Allen and Pepys may have been in their experiments, it
does not necessarily follow that their results must be con-
stant. They only operated on man, and on one other spe-
cies, the guinea-pig. We are therefore thrown back on
several of the causes of doubt mentioned above.
I saw no means of avoiding them but by paying a regard
to all, and varying the experiments so as to render the
conclusions independent of the sources of error by which
previous attempts had been affected. I therefore proposed
to myself, to multiply experiments, not only upon in-
dividuals of the same species, but also to submit to them
individuals of different species taken from the three classes
of vertebrata which perform atmospheric respiration : to
vary the conditions dependent upon age and external
circumstances : to diversify the mode of respiration from
the most laborious degree, to that which approaches near-
est to the natural state : to establish such a proportion
between the quantity of air respired and the bulk of the
individuals, that the quantity and bulk of the air re-
maining in the lungs could not sensibly affect the results:
to pay a scrupulous regard to measurement, and to es-
AIR FROM RESPIRATION. 215
timate how far the errors inseparable from it can affect the
conclusions.*
Since no process leaves respiration strictly in its natural
state, it was essential to compare the effects of a respira-
tion more or less constrained, in order to judge of the in-
fluence of such extraordinary respiration upon the mode of
alteration of the air.
By beginning with the longest confinement possible, and
diminishing it successively, in different series of experi-
ments, all the degrees of respiration are gone through. If
the effects are similar, without however being precisely the
same, we may judge what respiration must be in relation
to the alteration of the air, when it is in its natural and
healthy state.
I proposed to gain by this method, another advantage,
viz. that in the degrees of laborious respiration excited by
the experimental process, such alterations of this function
must present themselves as are met in diseases of the chest,
whence would result applications to pathology.
In the choice of my apparatus, I bestowed particular
attention to the means of measuring the quantities of air
before and after the experiment. It consists of a glass
globe, to which is fitted a tube whose diameter is large
enough to allow the introduction of the animal. As the
animals subjected to experiment were either adults of very
small species, or young animals of larger species, the
diameter of this tube was small enough to allow very
slight differences in the volume of the air to be determined
* There are two methods by which we may equally obtain a nearly natural
respiration. The first by renewing the air and collecting that which has been
breathed, as was done by Allen and Pepys. The second by keeping the animal
for a short time in a quantity of air which shall be large in proportion to the
bulk of the auimal. I chose the latter, as the more simple method, which is an
important advantage when experiments are to be multiplied.
216 ON THE ALTERATIONS IN THE
by the graduation. Each degree was equivalent to a quar-
ter of a centilitre, or "152 cubic inches. The graduation
was double, in order that the level of the mercury might
be well observed on both sides. The air, previous to the
experiment, was brought to the state of extreme humidity,
in order that the perspiration might not change its bulk.
The animal was introduced through the mercury, upon a
partition of iron wire, to the top of the tube, and supported
by a stem of the same material, fastened to the lower ori-
fice.
Section I. — Proportions of the oxygen which disappears,
and of the carbonic acid produced.
Three puppies, a day or two old, were introduced into
separate vessels of the description above mentioned, con-
taining 150 centilitres, or 91*5 cubic inches of air. They
remained there five hours. During the experiment it was
evident that there was an absorption of air ; for the mer-
cury rose in the tube, and it was necessary to pour a fresh
supply into the vessel in which it was immersed. It was
evident that the absorption was considerable, but the exact
measure of it could not be ascertained. From the analysis
of the respired air, it appeared that the three puppies had
produced nearly the same quantity of carbonic acid, of
which the mean was 17-86 centilitres, or about 10*90 cubic
inches, and that the absorption, likewise nearly the
same in all, was on an average 9*30 centil. or 5*67 cubic
inches, and that it was at the expense of the oxygen.
We shall now see what light this first experiment
throws on the nature of the gas absorbed. Is it pure
oxygen, or carbonic acid which mixes with the air during
respiration, or lastly, a mixture of both ? We shall, for
AIR FROM RESPIRATION. 217
the present, suppose that the two first hypotheses only are
possible ; we shall afterwards examine the last.
In the early stages of the experiment, when the respira-
tion begins, there is scarcely any carbonic acid in the ves-
sel ; but the quantity increases as the experiment proceeds.
If, therefore, it is this gas which is absorbed, the absorp-
tion will be scarcely sensible at first, will go on increasing,
and be at its maximum at the end of the experiment. On
the other hand, if it be oxygen, the reverse will take
place, since its proportion is largest at the commencement,
and diminishes progressively. Now the following are the
phenomena presented in the experiment. As soon as the
animals are introduced, scarcely any of the expansion of
the air, which must necessarily take place from the rise of
temperature, is indicated by the mercury in the tube ;
whence it results that absorption takes place from the be-
ginning, and consequently that it is the oxygen which is
absorbed. In confirmation of this we may observe that
when the absorption is evident by the ascension of the
mercury in the tube, it is more rapid at the beginning than
towards the conclusion of the experiment.
Three puppies, like the preceding, were placed in the
same conditions as in the first series of experiments ; but
instead of remaining five hours, they remained only two.
The average quantity of carbonic acid produced was 14*86
centil. or 9 cubic inches, and 7 centil. or 4*27 cubic inch
of gas were absorbed. In this instance the gas absorbed
was rather less than half the carbonic acid produced, and
in the former rather more than half. We see from this
how little influence the lengthened confinement of these
animals in air containing a pretty large proportion of car-
bonic acid, had on the proportion between the two quan-
tities, whence it is evident that the gas absorbed is prin-
cipally oxygen.
218 ON THE ALTERATIONS IN THE
Three very young cabias, or guinea-pigs, were subjected
to the same kind of experiment for 1 h. 42'. They pro-
duced each on an average 21*69 centil. or 13*23 cubic
inches of carbonic acid, and absorbed 5*44 centil. or 3*32
cubic inches of oxygen. The change of species occasion-
ed a striking change in the proportion of the oxygen lost to
the carbonic acid produced. In the case of the cabias, it is
as 1 to 4 ; in the puppies of the second series a little less
than 1 to 2. Besides the difference depending on their
species, the one being carnivorous, and the other herbivor-
ous, there is another very remarkable one, to which we
have frequently alluded, depending on their development.
The new-born cabias comes into the world in a more ad-
vanced state, which gives them the power of producing
more heat.
Hitherto we have seen that the proportion of gas ab-
sorbed to the carbonic acid produced, varies principally
according to the species and the age ; for in casting a
glance at the tables, it is evident that the mean quantities
differ but little from the particular results. But we shall
now observe the results of experiments upon other species,
in which the individuals differed much in this respect.
These examples are taken from birds, both in laborious
inspiration or in that which may be regarded as nearly
free and natural. The conditions of the experiment may
be so modified as to approach indefinitely to natural
respiration, by increasing the quality of air in proportion
to the bulk of the animal, and by shortening the period of
confinement,
I chose ten adult yellow-hammers, whose bulk was equal
to a little more than 3 centilitres or 1*8 cubic inches.
Each of these was placed in a vessel of the kind already
mentioned, containing 155 centil. or 94*5 cubic inches of
air. They remained there only 1 5 minutes. They produced
on an average 5'98 centil. or 3*65 cubic inches of car-
AIR FROM RESPIRATION. 219
bonic acid, and absorbed 1*29 centil. or *787 cubic inches
of oxygen. Here the small size of the animals, the large
proportion of air, the short duration of the experiment, the
quantity of carbonic acid, scarcely any at first, and in small
proportions at last, allow no room to doubt that the ab-
sorption was almost entirely at the expense of the oxygen,
and that the same would be the case in the open air.
In comparing the results of individual experiments of
this kind, considerable difference was observable in the
proportion of the oxygen absorbed to the carbonic acid
produced, ranging between rather less than half, and one-
sixth. The quantity of carbonic acid produced was very
uniform when the circumstances were similar.
Let us now descend to the other extremity of the scale of
vertebrata having atmospheric respiration, in order to as-
certain whether the results are similar, as to the absorption
of oxygen, by which I mean the disappearance of a portion
beyond that which corresponds to the carbonic acid pro-
duced.
Since reptiles alter the air much more slowly, their con-
finement must be considerably prolonged in order to obtain
effectual results. Its duration in this case, does not pre-
vent their respiration in a close vessel from sufficiently re-
sembling respiration in the open air, provided that the other
conditions before mentioned have been fulfilled, and that
they are taken out when they have produced a small quan-
tity of carbonic acid in proportion to the air in the vessel.
During the heat of summer, the thermometer being 27°
cent. 80°.6 Fahr. I tried nine experiments with the green
frog, rana escuknta, in 74 centil. or 45*16 cubic inches of
air, in which they were left 24 hours. They produced, on
an average, 5*26 centil. 3-23 cubic inches of carbonic acid,
and absorbed 2*18 centil. or 1'23 of oxygen. Other ex-
periments, made at lower, but moderate temperatures, did
220 ON THE ALTERATIONS IN THE
not fail to exhibit a considerable proportion of oxygen ab-
sorbed, compared to the carbonic acid produced.
Similar researches, made with grey lizards, had the same
success. It results from them that the proportion between
the oxygen which disappears, and the carbonic acid pro-
duced is very variable. The excess of the former varies in
such proportion, that sometimes it exceeds the third part
of carbonic acid formed, sometimes it is so small that it
maybe disregarded. This difference is not solely dependent
on the constitution of the species, but also on the compa-
rative degree of development, from difference in age, and on
individual differences among adults.
It is easy now to determine to what we must attribute
the diversity in the results obtained by the philosophers
who have been engaged with observations upon the che-
mical changes effected in the air by respiration. Those
who have inferred from their experiments, that the oxygen
which had disappeared exceeded the quantity of carbonic
acid produced, were not mistaken, even in the origin of
the researches upon this subject, when there were several
sources of error, in the measurement of volumes of air,
in the endiometric processes, and in the conditions of
the experiment, because there are numerous cases in which
this excess is so great, that it exceeds the limit of any
error which the observers of that period could possibly
have committed.
These results do not exclude those of Allen and Pepys,
who found the quantities of oxygen lost and carbonic acid
produced apparently the same, since we have seen above
that proportion varies greatly, and that in some instances
it approaches to equality. They employed the greatest
care to obtain accurate results, but their experiments were
with few individuals and very few species.
This result of my experiments upon respiration, in re-
AIR FROM RESPIRATION. 221
gard to the great extent of variation in the proportions of
oxygen which disappears, and of carbonic acid produced,
has appeared to be important, not because it reconciles the
results of previous labours, (though even that is not unin-
teresting), but because it establishes a fundamental fact of
importance to the theory of that function.
Since the period at which I presented this result to the
Academy of Sciences in 1821, additional proofs have been
furnished of the extent in which the proportions of oxygen
which disappear, and of carbonic acid produced, may vary
according to the species. For these we are indebted to
M. Dulong, who has compared, with his characteristic
talent, the quantities of heat developed by animals with
that which would proceed from respiration, in accordance
with the theory of Lavoisier. A notice of them is to be
found in the Journal de Phy&iologie de M. Magendie, Ja-
nuary 1823.
Section II. — On the Proportions of Azote in the Air in-
spired and expired.
We now come to a fundamental question relative to the
changes produced in air by respiration, upon which the
results of former observations differ still more than in the
preceding question. For in that there were only two op-
posite results ; one that the oxygen exceeds the carbonic
acid, the other that it equals it; whereas in the present
question there are all the contradictions possible. 1st, That
the inspired is equal to the expired azote. 2nd, That it is
greater ; and 3d, That it is less.
The examination of the alteration in the air, by the re-
spiration of new-born puppies and guinea-pigs, in a num-
ber of experiments, shewed that, with a single exception,
222 ON THE ALTERATIONS IN THE
there was in all the cases an augmentation of the quantity
of azote. Now, if in some of them the quantities were
small, in others they appear to me beyond the limits of any
errors that I could have committed, and I therefore con-
clude that they are the effect of the exhalation of azote ;
and since this effect took place in both the first and second
series of experiments, wherein animals of the same species
and the same age had remained in the air during very dif-
ferent times, I considered that the same would hold with
natural respiration.
In the tabular view of my experiments upon the respi-
ration of birds, the columns referring to azote exhibit the
same result in all the cases in which the birds remained a
long time in the respired air, although for different periods,
and at different temperatures. The respiration of frogs in
my experiments, must be regarded as natural, or nearly so,
on account of the slight alteration in the proportion of
oxygen and the small quantity of carbonic acid at the end
of the experiments. There was, in almost all, an excess of
azote, and in the greater part, a quantity sufficiently re-
markable to admit of being attributed to exhalation. The
same may be said of lizards.
Of the numerous experiments which are recorded in the
tables, and of many others which are not mentioned,
the result was, that in almost all the cases there was an
excess of azote ; but the consideration of the differences
leads necessarily to the two following conclusions : —
1. In a large number of cases the azote inspired and ex-
pired so nearly approaches to equality, that the slight dif-
ference may be disregarded, and exhalation rejected.
2. In a great number of other cases the excess of azote
is so considerable that the exhalation of this gas cannot be
denied, inasmuch as the quantity greatly exceeds the vo-
AIR FROM RESPIRATION. 223
lume of the lungs, and bears a large proportion to that of
the animal.
These results were met with in the experiments of both
series and with species the most widely different.
I should have paid no attention to the very small number
of cases in the tables, in which there was a loss of azote in
the expired air, since in nearly all of them the difference
was so small, that I could not have attributed it to absorp-
tion, if other experiments had not furnished me with fur-
ther data.
Let it be remarked in the first place, that the foregoing
facts refer to experiments made in spring and summer
months.
We shall now call the reader's attention to the tables of
experiments made in autumn and winter.
The exhalation of azote was still taking place on the 22d
of October, as shewn by experiments on adult sparrows.
From the 26th the phenomena are reversed, and the loss of
azote becomes as striking as the excess had been before,
the attending circumstances still remaining the same.
As this series of experiments was made upon individuals,
which remained as long as possible in respired air, it might
be believed, that this absorption of azote would not have
taken place during natural respiration, but it must be ob-
served, that the same phsenomenon was produced by so
short a confinement, that the respiration approached very
nearly to that which takes place in the open air.
Yellowhammers which were kept only 15 minutes in
155 centil. or 94*6 cubic inch, of air, which they very little
deteriorated, produced in the month of November, in
almost every instance, a diminution in the quantity of
azote.
We see that these two series of experiments, made upon
adult sparrows and yellowhammers, in a different season,
224 ON THE ALTERATIONS IN THE
present us with a phenomenon directly the reverse of that
which we formerly shewed. I have proved it on the same
species of birds, in autumn, in winter, and at the beginning
of spring.
During the cold season the exceptions were extremely
rare, but in pursuing these researches with the same species
of birds, I observed that the phenomena became reversed.
I first observed this in the spring ; it continued through
the summer, and with a very few exceptions during the
commencement of Autumn. Although nothing could
have made me anticipate the relation between the inspired
and expired azote, noticed in the preceding cases, and
which continued throughout the period of fine weather, I
was led to expect that inverse phenomena would prevail
from some period of the autumn. This was a powerful
inducement for me to continue this species of experiment,
and I obtained results which I have exhibited in the tables.
In the series of experiments relating to birds, the quantities
of inspired and expired azote are variable^ but may be
classed under three heads, namely ; 1st, of equality be-
tween the two gases, and 2ndly, of the excess of one, and
3rdly, of the excess of the other. If the difference between
the inspired and expired azote had been quite irregular and
confusedly scattered throughout the course of the experi-
ments, no reliance could have been placed in them, but on
the other hand, when we see these differences, however
slight, constantly bearing for a considerable period in one
direction, and then having an opposite tendency during an
equal space of time, notwithstanding the identity of the
mode of experiment, we cannot but conclude that a real
change has taken place in the subject under investigation.
But what is more subject to change than a living animal ?
Have we not already seen in the course of this work, that
striking changes take place in the constitution of these
AIR FROM RESPIRATION. 225
very animals ? It was this change in their constitutions in
successive seasons, which made me presume that a change
might also take place in the effect produced upon inspired
air, and made me undertake a series of researches con-
tinued throughout the year. Considering then the inspired
and expired azote abstractedly and without connexion with
the causes which may make them vary, we may assert, not only
that the one may at times exceed the other, but that their
extreme differences are the same on both sides.
This difference in the inspired and expired azote has
never equalled the greatest difference observable between
the oxygen which disappears and the carbonic acid pro-
duced ; so that the two former quantities tend much more to
an equality. This tendency is so great, that in many
cases, the differences have been too slight to be regarded
as real.
With respect to the causes of the variations, they are
probably very numerous and difficult to be ascertained.
As to the influence of the seasons, the effect of which we
have observed on adult yellow-hammers and sparrows, it
is evident by these very experiments, that that case does
not always prevail over the others, since there are cases
in which absorption was sensible in summer and exhalation
in winter. It is true, that I have observed the absorption
of azote in winter, in adult bats and mice ; but I have not
repeated my experiments upon these species as 1 have done
with the former. As to very young animals, such as young
guinea-pigs, I have scarcely ever observed anything but the
exhalation of azote both in winter and summer.
Section III. — On the Exhalation and Absorption of Azote.
The principal experimenters who have proved the absorp-
tion of azote in the respiration of vertebrated animals, are
Q
226 ON THE ALTERATIONS IN THE
Spallanzani, Humboldt, Davy, Pfaff, and Henderson. They
have frequently done so to an extent which precludes doubt.
Allen and Pepys and Dalton found no sensible change in
the quantity of this gas when the animals breathed as nearly
as possible in the natural way. An increase of the azote
was observed by Bertholet and Nysten. Although the latter
found an excess of azote to an extent which could not be
ascribed to a fault in the analysis, the fact of the exhalation
of azote in respiration was the point most requiring con-
firmation. Independently of the proofs which I have given,
it has recently been confirmed by the researches of Dulong.
Humboldt and Provencal, in their long series of experiments
upon the respiration of fishes, have proved that these ani-
mals absorb a large quantity of azote. Spallanzani recog-
nized the absorption of azote by reptiles and various species
of warm-blooded animals. Davy observed it in his own
person in so many instances as to leave no doubt of
the fact. The same was the case with Pfaff and Hen-
derson.
From our being accustomed to find a constancy in the
phenomena of inorganic nature, and habituated to judge of
the truth of the results of experiment by the possibility of
our reproducing them at pleasure, we are led to seek with
anxiety for the same character, in an order of facts which
are necessarily variable. Hence the difficulty of obtaining
general assent to the results of physiological experiments,
which by their nature are precluded from offering that uni-
formity on which the mind reposes with confidence.
Convinced that different and even opposite results do
not necessarily exclude each other, when vitality is con-
cerned, I have always endeavoured so to vary my experi-
ments, that I might reproduce some of the phasnomena
which appear contradictory in the works of other physiolo-
gists. This has been particularly the case with respect to
AIR FROM RESPIRATION. 227
the subject of respiration, and especially with reference to
azote. It remained to seek for the links by which these dif-
fering phaenomena might be connected.
In the different experiments which exhibit, on the one
hand, a diminution in the quantity of azote, and on the other
an increase, there are two ways of considering these results.
We may either regard the diminution as attributable to ab-
sorption unaccompanied by exhalation, and the increase as
arising from exhalation unaccompanied by absorption, or
we may regard both functions as acting together, and attri-
bute the diminution or increase to the predominance of the
one or the other. The question which of these views is
correct, cannot be decided by direct experiment, for we
can never observe in the same experiment, that both ab-
sorption and exhalation of azote take place at the same
time. "We must then have recourse to indirect methods,
by which, however, the same certainty can be obtained.
Let us suppose the case of an animal, giving as the result
of an experiment, equality in the inspired and expired azote,
or differences so slight that thev might be disregarded.
On the hypothesis that the result is due to the equal per-
formance of the two functions, there would be a certain
means of destroying the equilibrium. We cannot, indeed,
prevent the animal from exhaling azote ; but he may be
placed in such conditions that he could not absorb it, ex-
cept in qualities so small as not to affect the result.
This was the object of the enquiry in which I engaged,
after I had presented to the Academy of Sciences the paper
on respiration already mentioned ; but my researches were
scarcely wanted. Experiments on this subject had already
been made, though with very different views. Allen and Pepys
performed them with the greatest exactness. The results
are unequivocal, and might easily be foreseen after the
views which I have detailed.
q2
228 ON THE ALTERATIONS IN THE
The apparatus need not be described ; suffice it to say,,
that the animal was placed in such conditions that its re-
spiration was nearly the same as that which it performs in
the atmosphere, by keeping up a change of air, by a con-
stant and uniform current.
These authors placed a guinea-pig in their apparatus,
in which the animal was as well as in the open air. They
found after the experiment, that the quantity of azote was
sensibly the same as before. This result, in conformity
with others, persuaded them that the azote undergoes no
alteration in free and natural respiration.
In the same apparatus, instead of azote, they employed
oxygen, which was not absolutely pure, but which con-
tained 5 per cent, of azote. They placed in it an animal
of the same species, and maintained a current of the gas
as in the preceding experiments. The animal appeared in
good condition. From the result it appeared that the ex-
halation of azote was considerable, and it was impossible
to attribute the excess of azote to the quantity in the lungs
at the commencement of the experiment ; for the volume of
this gas expired considerably exceeded that of the animal.
The authors were led to believe, that the exhalation was
due to the extraordinary circumstance of the respiration of
oxygen ; but it takes place equally in atmospheric air, as
is proved by the results which I have obtained, and by the
facts stated by M. Dulong. It is true, the quantity is va-
riable ; but there can be no doubt, that this exhalation is a
natural phenomenon.
Let us suppose, that an animal is made to inspire an
artificial air, composed of oxygen and hydrogen, in the same
proportions as those of atmospheric air. According to the
views above stated, it may be foreseen, that in consequence of
the absence of the azote, the exhalation of this gas will be
very evident, and that the hydrogen will be absorbed as all
AIR FROM RESPIRATION. 229
other gases are. The experiment has been made by Allen
and Pepys, with the same precautions as in the preceding
cases ; and the results have been precisely similar to those
deduced from the views above-mentioned. The exhalation
of azote was so great as to exceed the bulk of the animal,
and there was a considerable absorption of hydrogen.
Here is a proof that the two functions are performed at the
same time, and the key to the observations above recorded,
that in different cases, we may find equality, excess, and
loss in the azote expired, when compared with that in-
spired.
Section IV. — On the Production of Carbonic Acid in
Respiration.
There are only two essentially different ways of consider-
ing the production of carbonic acid in respiration. Accord-
ing to one, the oxygen of the inspired air enters through
the air-cells of the lungs into contact with the blood in
the lungs, unites with a portion of the carbon of this
fluid, and thus forms carbonic acid.
According to the other view, the oxygen which disap-
pears is entirely absorbed, and replaced by carbonic acid.
Lavoisier was fully aware of this, and" observes in his
first memoir on respiration : " On this subject I find myself
led to two equally probable suppositions, between which
experiment has not yet enabled me to decide. In fact,
from what has just been stated, we may conclude,
that in respiration one of two things happens ; either that
the highly respirable portion of the atmospheric air is con-
verted into the aeriform acid of chalk (carbonic acid gas)
in passing through the lungs, or else that an exchange is
made in those organs. On the one hand, the respirable
230 ON THE ALTERATIONS IN THE
part of the air is absorbed ; and on the other, the lungs
substitute for it a nearly equal volume of the aeriform acid
of chalk." Notwithstanding the perfect impartiality with
which he expresses himself with respect to the probability
of these two modes of viewing the formation of carbonic
acid, he avows his belief, that both modes operate in the
act of respiration. But as he proceeded in his chemical
researches on the formation of carbonic acid by the com-
bustion of carbon, and on the heat produced by it, and
continued his physiological enquiry on respiration, it was
difficult not to perceive the analogy between these two
orders of phaenomena, and he therefore preferred the former
hypothesis, viz. that the carbonic acid is formed in the lungs
by the combination of the oxygen with the carbon of the
blood. He had not finished these labours on respiration, when
he was cut off by a premature and melancholy death. Had
he lived, he might have sought to determine by experiment,
as he intended to have done, what was the true hypothesis.
That which he adopted explained all the known facts con-
nected with respiration, and had the rare advantage of ac-
counting in a satisfactory manner for a most important func-
tion, the production of animal heat.
It is remarkable that Spallanzani, whilst he thought
that he was adopting the opinion of Lavoisier, held the
opposite one, and sought to establish it by experiments,
which, had they been exact, would have upset the generally
received doctrine. These experiments were not published
till after the death of Spallanzani, when M. Senebier gave
a translation of the unpublished manuscript. The facts in
question, although published in 1803, in a work which was
generally known, remained as it were buried, since they
had no influence on the views which were taken of the
phenomena of respiration, and led no one to undertake a
\eries of experiments to settle the question.
AIR PROM RESPIRATION. 231
There is only one mode of deciding by experiments be-
tween two hypotheses, namely, that employed by Spallan-
zani. It is evident that if the carbonic acid results from the
combination of the oxygen of the air with the carbon of the
blood in the act of respiration, it will not be produced in
the case of an animal respiring a gas which contains no oxy-
gen. It is unnecessary to add, that regard must be paid to
the oxygen and carbonic acid which the lungs may contain
when the animal is subjected to the experiment.
There is a difficulty, however, in making choice of a
suitable species of animal for this experiment. The quan-
tity of pure azote or hydrogen which man can inspire with-
out danger, is too small to admit of any conclusion being
drawn from experiment on human beings. The same re-
mark is applicable to other warm-blooded animals.
• On the other hand, if animals are selected from distant
classes, like the invertebrata, from the mollusca for ex-
ample, as was done by Spallanzani, we feel little disposed to
admit as a general phenomenon the results of experiments
made upon beings of so inferior an order, whose organiza-
tion appears so different from ours.
Among the cold-blooded vertebrata which perform atmo-
spheric respiration, the batrachians are almost the only ani-
mals which unite the necessary conditions, viz. the capa-
bility of living for a considerable time without oxygen,
the power of producing respiratory movements when so
circumstanced, and the possession of lungs of small capacity.
But the batrachians do not possess these advantages at
all seasons. It has been shewn in an early part of this
work, that both a high present temperature and the in-
fluence of a continued previous exposure to a high tempe-
rature greatly shorten the time which these animals can
endure the privation of oxygen ; nor can they at all seasons
and in all media perform the respiratory movements in the
232 ON THE ALTERATIONS IN THE
absence of oxygen. With regard to the lungs, their orga-
nization renders them extremely well adapted to experi-
ments of this nature ; for by pressing the flanks the air which
they contain can be expelled previously to introducing the
animals into hydrogen.
I made my first experiments in the beginning of March,
when I knew that frogs could live sufficiently long in
hydrogen to afford me a satisfactory result. Vessels were
employed, similar to those described in page 2 15. That
the hydrogen might be obtained as pure as possible, it was
disengaged by means of zinc, sulphuric acid, and water,
and, previously to collecting it, I passed it through a strong
solution of caustic potass, and it was collected over boiled
water, that there might be no admixture of atmospheric
.air. In addition to all these precautions, it was proved, by
means of analysis, to contain neither carbonic acid nor atmo-
spheric air, and its passage through the potass had deprived
it as much as possible of any adventitious odour.
The ball was filled with 153 centilitres, or 93 cubic inches
of this hydrogen, and was placed over mercury. A frog
was introduce:! upon a partition of wire gauze, supported
by a stem fastened to the lower aperture of the tube. The
animal performed, for a long time, very ample and very
regular respiratory movements. They however declined,
and ceased before the end of the experiment, which lasted
8h. 30m. The animal, although it had ceased to move,
was not yet dead. Exposed to the air, it recovered some
time afterwards. The comparison of the volume of gas,
before and after the experiments, evinced that gas had been
exhaled. A portion of the air in the ball was afterwards
analysed in a graduated tube, with a solution of caustic
potass, and found to contain a notable quantity of carbonic
acid. The quantity of carbonic acid contained in the hy-
AIR FROM RESPIRATION. 233
drogen in which the animal had breathed, amounted to
2.97 centil. or 1*8 cubic inches, which is nearly equal to the
bulk of these animals. Now this could not have proceeded
from the air contained in the lungs ; for, in plunging the
animal under mercury in order to introduce it into the
apparatus, care had been taken to compress the flanks so
as to expel the air. This compression may be carried so
far as to push the lungs into the throat where they may be
seen absolutely free from air. Besides, these organs are so
small that the quantity of carbonic acid which they can
contain, would not be sensible to ordinary eudiometers,
when so large a volume of hydrogen is employed as was
used in the experiment. The carbonic acid was therefore
entirely the product of exhalation.
I could scarcely doubt the accuracy of this result ; but
for greater satisfaction, it was repeated several times,
with the most scrupulous attention to the exactness of the
measurement; and these repeated trials clearly proved,
that these animals placed in pure hydrogen, exhaled car-
bonic acid in variable quantities, according to the indivi-
duals and the duration of the experiment. Sometimes the
quantity bore a considerable proportion to their bulk, at
other times it equalled if not surpassed it.
As I advanced in this verification, it happened, as I had
foreseen in commencing these researches, that the duration
of the experiment necessarily diminished from the alteration
in the constitutions of the animals. They were begun on
the 1st of March. The temperature was then 10° cent, or
50° Fahr., and although it varied in the course of the expe-
riments, it scarcely ran higher during that time. The ani-
mals at first lived at least eight hours in hydrogen ; but the
period ere long sensibly diminished, and at length was
reduced to half, shewing the influence of the continued
operation of that temperature in changing the winter con-
234 ON THE ALTERATIONS IN THE
stitution. But another phenomenon, no less remarkable, is
that which is presented by the organs which perform the
respiratory movements. When these animals are under
the influence of the cold season, they execute the respira-
tory movements in an atmosphere of hydrogen with the
same force and the same continuity as in atmospheric air.
They preserve enough of the constitution acquired during
winter to breathe in hydrogen in the same manner in the
beginning of spring, but as the season advances, they lose
that power, and are then affected in this gas nearly as they
are in water at all seasons of the year, that is, as soon as
they are introduced into it, the respiratory movements cease
or become very rare, although they may live for some hours.
They therefore then become ill adapted to experiments of this
nature from the shortness of the duration of their life, and
the cessation or rarity of the respiratory movements. They,
however, still continue to produce carbonic acid through the
medium of the skin ; a fact which I took care to ascertain.
I wished to extend these researches to other vertebrata,
and hoped to obtain satisfactory results in the class of
fishes. My previous researches on the duration of the life
of fishes in water deprived of air had taught me, that the
species known by the name of golden-fish, cyprinus aureus,
was the best adapted for experiments of this kind, since
they have the power of living longer than other fresh-water
fish in this liquid deprived of oxygen. Although the season
was not very favorable, it being in the spring, after I had
completed my experiments upon frogs, I nevertheless under-
took the enquiry with this species of fish. I put two of them,
of small size, into a similar vessel to that which I have before
described, and containing pure hydrogen. They were sup-
ported, like the frog, by a partition of wire-gauze. Ano-
ther fish of the same size was placed in a vessel of the same
form, but of smaller capacity. The animals in both vessels
AIR FROM RESPIRATION. 235
performed respiratory movements, which consist, as is
known, in the beating of the gills, but these movements
were weaker, less frequent, and less regular than in aerated
water or common air. The experiment lasted 5h. 5m. One
of the fishes still exhibited respiratory movements : but they
had ceased in the others. Fishes have, like the batrachians,
the power of living pretty long after the cessation of the
respiratory movements ; so that I did not take them out as
soon as I ceased to perceive motion. On analyzing a por-
tion of the air respired by the fishes in each vessel, I found
that they had produced carbonic acid in the hydrogen.
After having obtained this result with animals selected
from two classes of the vertebrata, I descended in the scale
and proceeded to the examination of animals without ver-
tebras. I took the same species of snail that Spallanzani
had employed, the helix pomatia; I introduced two of them
into the tubulated globe, containing 147*5 centil. or 90
cubic inches of hydrogen. Care must be taken that they
are drawn into the shell at the commencement of the expe-
riment, in order that no air may be left between that cover-
ing and the body.
Placed in the ball and supported on the wire-gauze, they
were not very eager to come out of their shells, but ere long
they did so, and even crawled about in the vessel. What
was most remarkable in this experiment was its duration ;
although it was made in April, they were seen, 24 hours
after their introduction, to exhibit themselves and move in
the globe as if they had been in atmospheric air. Their
motions were not constant, nor are they so in the atmosphere.
I left them in the hydrogen for 48 hours, and although
they then had little or no motion, they were still alive.
The measure of the volume of air, before and after the
experiment, shewed by its increase that there had been an
exhalation of gas. The nature of a portion of this gas
236 ON THE ALTERATIONS IN THE
could scarcely be doubted after what we formerly stated, and
analysis enabled us to discern the presence of carbonic acid
as Spallanzani had previously found. The long period of
the experiment, during which these animals shewed suffi-
cient activity to allow me to believe, that the function of
exhalation had not been much controuled, led me to hope
for a considerable quantity of carbonic acid in proportion to
their bulk. In this I was not disappointed. I found in
the hydrogen 2*79 centil. or 1*7 cubic inches of carbonic
acid, which is about equal to their bulk. I obtained a
similar result on repeating the experiment.
We may here stop to enquire, whether the phenomenon
presented in the above experiments must be restricted to
those species exclusively on which the experiments have
been tried ; or whether it may not, from analogy, be extend-
ed over the animal kingdom generally.
There will, probably, be no hesitation in applying to other
reptiles the results of the experiments upon the frogs, and
in making similar concessions in regard to fishes in general,
as well as to the animals without vertebrae. But some may
restrict the inference to these limits, and not admit of its
application to mammalia and birds, on the plea that these
animals are of a superior order, and distinguished from those
above-mentioned by the great quantity of heat which they
produce. In reply it may be observed, that the pheno-
menon in question is so fundamental in the animal economy^
that it cannot be supposed to be essentially different in mam-
malia and birds from what it is in other animals ; that the
power of producing heat is common to all ; that the high
temperature which seems to characterize the mammalia and
birds does not belong to them exclusively, since examples
of it are found among insects; that, on the other hand,
among the mammalia themselves there are species, which
at certain periods, present the principal phenomena of
AIR FROM RESPIRATION. 237
cold-blooded vertebrata: such are the hibernating mam-
malia in autumn and winter; and lastly, that a great num-
ber of non-hibernating mammalia and birds, in the early
periods of their life, shew, as far as the phenomenon of heat
is concerned, a strong resemblance to cold-blooded animals.
I had no doubt of the validity of the above arguments, yet,
as I was desirous of giving complete satisfaction, if possible,
by direct proofs, I hoped to be enabled to do so by availing
myself of the power which certain new-born species of
mammalia have of living; for about half an hour without the
contact of the air. These species appear to combine the
qualities requisite for the success of the experiment. When
they are deprived of air, the respiratory movements are not
suppressed, but they are rare. After two or three minutes,
the voluntary motions cease, and are succeeded by others
which are involuntary, consisting in strong respirations
accompanied by yawnings, and flexions of the trunk. These
movements are repeated about every minute, so that if they
live an hour they may furnish about thirty inspirations. In
the case of reptiles, such a period would be much too short,
from their languid power of producing carbonic acid ; but
the mammalia, although they produce less carbonic acid in
the early periods of their life than they do afterwards, fur-
nish sufficiently more than reptiles to compensate for the
short duration of the experiment, and the limited number
of inspirations. The smallness of their lungs is another
advantage without which, indeed, the experiment ought
not to be attempted. I made trial of it upon a kitten, three
or four days old. I employed the same apparatus with
146 centilitres of hydrogen. It performed movements, at
various intervals, for 1 9' only ; which gave, after the ces-
sation of voluntary motion, about as many inspirations. I
drew it out four minutes after, and when the apparatus was
completely cooled, I found a very sensible quantity of car-
238 ON THE ALTERATIONS IN THE
bonic acid, being 1*96 centil. or very nearly 1*2 cubic inches.
Now it became a question to compare this with the capacity
of the lungs. I removed them from the animal with the
trachea ; and then inflated them as much as possible, which
distended them beyond their natural bulk ; I then intro-
duced the air which they contained into a graduated tube.
It amounted to only four-fifths of a centilitre, or "48 cubic
inch. Now, supposing that all the oxygen of this bulk
of air had been converted into carbonic acid, which is an
exaggerated supposition, there would then have been only
the fifth of this bulk of carbonic acid, or 0-16 centil. which
is about 0*97 cubic inches, whereas we found 1*96 centil.
or about 1 *2 cubic inch.
In applying to the process of respiration in atmospheric
air, all that can be fairly inferred from the preceding expe-
riments, we conclude, that at least a portion of the carbonic
acid produced, is not the result of the immediate combina-
tion of the oxygen of the air with the carbon of the blood in
inspiration, but is the product of exhalation.
We have now to ascertain whether what is true of a part
is true of the whole ; whether one portion of the carbonic
acid is exhaled and another formed entirely in the lungs
from the oxygen of the air and the carbon of the blood ; or
whether it is entirely the product of exhalation, since both
suppositions are possible.
If, when an animal breathes in atmospheric air, a part of
the carbonic acid is exhaled, and the other formed at once
in the lungs by the presence of oxygen, it follows that in
making it breathe from hydrogen, the quantity of carbonic
acid produced will be reduced to that which he exhales, and
that it will be less than the quantity produced in atmo-
spheric respiration by the whole portion which is supposed
to be formed in the lungs. Spallanzani compared the pro-
duction of carbonic acid by snails placed in hydrogen with
AIR FROM RESPIRATION. 239
that of others in atmospheric air, and obtained this re-
markable result, that they produced at least as much car-
bonic acid in the former case as in the latter. I shall give
the result of my own experiments made with vertebrated
animals. Here the choice of the species is more confined
than in the preceding experiments. In them it was suffi-
cient that the animal breathed, no matter how, but with-
out regard to the manner, provided it was sufficiently long
to give assurance of the exhalation of carbonic acid. Here
it is necessary in addition, that the animal should breathe
with the same rapidity and to the same extent in hydrogen
as in atmospheric air, which never can take place in warm-
blooded animals, whatever be their age or their species. It
is only the cold-blooded vertebrata which are at all adapted
to it, and even among them the number of species, and the
season at which they have this power, are very limited.
At the temperature of 18° cent, or 64° Fahr. in July 1821,
three frogs, each placed in a tubulated glass globe, as above
described, containing 74 centilitres, or 45 cubic inches of
atmospheric air, after a confinement of twenty-four hours,
gave on an average, 2*57 centil. or 1*56 cubic inch of
carbonic acid.
The same experiment repeated upon three individuals of
the same species in October, the air being at 14° cent, or
51° Fahr. gave in the same time, about the same quantity,
viz. 2-77 centil. or 1-69 cubic inches. These results differ
little from the average.
When formerly treating of the subject of the respiration
of frogs in hydrogen, we mentioned that we had obtained
2-79 centil. or 1-7 cubic inches of carbonic acid. The
temperature was nearly the same ; but it is remarkable,
that this quantity of carbonic acid was exhaled in 8h. 30m. ;
whilst in atmospheric air we find a similar quantity at the
end of twenty-four hours. I shall not, however, insist upon
240 ON THE ALTERATIONS IN THE
this difference in favour of exhalation in hydrogen ; I shall
be satisfied with concluding from this comparison, that the
quantity of carbonic acid which these animals exhale in
hydrogen, under favourable circumstances, is not inferior
to that which they produce in atmospheric air, and that
consequently when they breathe in the atmosphere, car-
bonic acid is not formed at once in the act of respiration by
the combination of the oxygen of the air with the carbon of
the blood, but is entirely the product of exhalation.
This result with frogs is so completely in accordance with
that obtained in Spallanzani's experiments with snails, that
I thought it needless to repeat his experiments.
Now, as the fact in question has been verified on the one
hand upon the cold-blooded vertebrata, and on the other hand
upon the mollusca, and as the comparison cannot be estab-
lished by experiments upon warm-blooded animals, nothing-
appears to me to prevent our admitting the principle as
general.
Some of these experiments afforded fresh opportunities of
confirming the exhalation of azote as stated in the preced-
ing section. In some instances it amounted to five or six
per cent., considerably exceeding the volume of the ani-
mals. The absorption of a no less considerable portion of
hydrogen was also noticed.
The above experiments only prove the fact of the exhala-
tion of carbonic acid. From what source does this gas
proceed ?
It may be said that it proceeds from the blood, the com-
mon source of all the secretions, or it may be supposed that
it proceeds only from the air with which the tissues may be
impregnated.
The latter supposition is certainly possible, but is it
equally probable ? An animal is placed in hydrogen, and
when the conditions are favourable, it is seen to perform
AIR FROM RESPIRATION. 241
respiratory movements to the same extent and frequency
as if it were in atmospheric air. If we suppose a vertebrated
animal having atmospheric respiration, the hydrogen which
he respires becomes loaded with carbonic acid, which, we
are to suppose, it does not produce in the same manner as
in atmospheric air ; also, that its skin, which furnishes
carbonic acid in both of the gases, does not furnish it in the
same manner, but that its tissues, which are impregnated
with this gas, disengage it as soon as it is in contact with
the hydrogen ; whilst, when placed in atmospheric air, it
wholly retains the gas in its tissues, and, notwithstanding,
produces an equal quantity of carbonic acid, by the
contact of oxygen with the blood at the surface of the
body.
This supposition thus traced to its consequences seems to
refute itself ; we shall therefore conclude, that both in hy-
drogen and in atmospheric air, the carbonic acid is due to
exhalation, and that it proceeds wholly or in part from the
blood.
Here the question presents itself, whether the carbonic
acid is wholly formed in the general circulation, or whether
it is produced only in the lungs and the skin, where it is ex-
haled as it is produced.
There are well attested facts, which prove that carbonic
acid exists in the mass of the blood : such are the results
obtained by Vauquelin, Vogel, Brande, and Sir Everard
Home. The experiments of Vauquelin are, I believe, un-
published ; but for a number of years he has shewn in his
lectures, that blood placed in hydrogen disengages carbonic
acid.
242 ON THE ALTERATIONS IN THE
Section V. — General View of the Alterations of the Air in
Respiration.
The oxygen which disappears in the respiration of atmo-
spheric air is wholly absorbed. It is afterwards conveyed,
wholly or in part, into the current of circulation.
It is replaced by exhaled carbonic acid, which proceeds
wholly, or in part, from that which is contained in the mass
of the blood.
An animal breathing atmospheric air also absorbs azote ;
this is likewise conveyed wholly, or in part, into the mass of
the blood.
The absorbed azote is replaced by exhaled azote, which
proceeds wholly, or in part, from the blood.
Here are four fundamental points :
1st. The absorption of oxygen which disappears.
2d. The exhalation of carbonic acid which is expired.
3d. The absorption of azote.
4th. The exhalation of azote.
The two first relate to the oxygen, the two others to the
azote.
According to this view, respiration is not a purely che-
mical process, a simple combustion in the lungs, in which
the oxygen of the inspired air unites with the carbon of
the blood, to form carbonic acid, to be expelled ; but a
function composed of several acts. On the one hand there
are absorption and exhalation, attributes of all living be-
ings ; on the other the intervention of the two constituents
of atmospheric air, oxygen and azote.
This view is not a preconceived idea, but a result to
which we have been necessarily led by a multitude of
facts.
It exhibits to us animated beings drawing from the com-
AIR FROM RESPIRATION. 243
position of the atmosphere two of their constituent prin-
ciples.
It furnishes us with numerous inferences, several of which
are supported by facts already received in science.
Thus the oxygen which disappears being absorbed, and
the carbonic acid exhaled, the relative proportions are ne-
cessarily variable, from the nature of the two functions
which must vary in the extent of their action. The fact is
beyond doubt. They may vary in three ways. 1. The car-
bonic acid may be expired in smaller quantity than the
oxygen which disappears; 2. in equal quantity; 3. in excess.
The first is the ordinary case ; the second is supported by
the experiments of Allen and Pepys ; the third, if it is not
yet established, will probably be so hereafter. I might even
say that it is so already, when we revert to the experiment
of Allen and Pepys, relative to respiration in factitious air,
composed of oxygen and hydrogen. The same observation
applies to azote absorbed and exhaled.
Let us return to the oxygen, and consider what becomes
of it in the system. When it is absorbed and carried into
the blood, there is every reason to believe, that it contributes
to the formation of carbonic acid. But the experiments
which I have already detailed prove, that it cannot be the
only source of the gas contained in the blood.
Since we have shewn, that certain species of animals can
exhale in a given time, as much carbonic acid in hydrogen,
as in atmospheric air, there must be one or more subsidiary
sources for the carbonic acid contained in the blood. It is
easy to point out one. We know, from the researches of
Jurine, Chevreul, Magendie, and others, that this gas exists
in almost the whole extent of the alimentary canal. We
cannot but admit, that it is formed in the process of diges-
tion. It is in contact with almost the whole mucous surface
of the alimentary canal, and a part must be absorbed. If
r2
244 ALTERATIONS IN THE AIR FROM RESPIRATION.
any doubt of this were entertained, cases might be cited in
which water impregnated with carbonic acid, and drunk in
sufficient quantity, has produced symptoms of asphyxia.
Doctor Desportes has communicated observations on this
subject to the Royal Academy of Medicine.
With respect to the oxygen which is to contribute to the
formation of the carbonic acid contained in the mass of the
blood, one of two things must happen. It enters into com-
bination either suddenly or slowly. In the latter case there
will be oxygen in excess, circulating in the mass of the
blood. This pure oxygen will therefore be subject to exha-
lation, which will take place in the organs adapted for giv-
ing passage to it, as happens in fishes, in the air bladders
of which animals oxygen is found. I propose following
up this subject, and examining different kinds of blood, in
conjunction with M. Dumas.
245
CHAPTER XV.
APPLICATIONS.
As examples of the applications resulting from the general
conclusions which we have established, let us first take
some facts regarding the power of producing heat.
It has been shewn, that this power may vary con-
siderably in the same individual, in health ; much more
must we expect, that it will do so in a state of disease. Let
us deduce from the facts formerly laid down, what may
happen in those cases in which the power of producing heat
is reduced below the type of health.
I. There are two principal forms, as we have formerly
shewn, in which this state presents itself: a successive
diminution in the activity of the principal functions, pro-
ducing torpor ; or, on the contrary, an increase in the ra-
pidity of the movements of respiration and circulation. The
first case is that of hybernating animals ; the second that of
warm-blooded animals not hybernating. Without entering
into an examination of the conditions which determine these
forms, there are many reasons for believing, that they may
take place in adult individuals of any class among warm-
blooded animals. There is too great a diversity of structure
246 APPLICATIONS.
in warm-blooded hybernating animals to believe, that there
is only one peculiar organization which is susceptible of
presenting these phenomena. Structure, no doubt, exerts
some influence on the facility with which this state of hy-
bernation is produced, and on the period of its duration ;
but no organization would appear to be absolutely incapable
of it. Constitutions may so change by a concurrence of
circumstances, and the continuation of their influence, that
a similar change in animals, which we have not hitherto ob-
served in that state, is by no means impossible. The spe-
cies of warm-blooded animals, known to be hybernating,
are not so necessarily. They may cease to be so. There
are individuals among them which do not become torpid in
the season of hybernation ; a fact frequently observed in the
domestic state. It is sufficient in this case, that their power
of producing heat should be increased ; a power, in all ani-
mals, susceptible of varying between very distant limits.
This change can even be produced at pleasure, in some, by
suitable food, and a graduated temperature.
Let it not be supposed, however, that the principal phse-
nomena of hybernation, in animals habitually susceptible
of it, are only determined by a certain reduction of the ex-
ternal temperature. I have observed in many of those ani-
mals, that sleep, in summer, reduced their temperature con-
siderably, that their respiration was likewise diminished,
and that they became torpid ; only their torpor was not so
profound as in other circumstances. This effect of natural
sleep is so clearly connected with the power of producing
heat, that it is in general most strongly marked when this
power is the least. Bats and dormice afford a striking illus-
tration of this. Although this modification of function is
essential to the production of the phenomenon, I am far
from contending that it alone is always sufficient. The
state which characterizes hybernation may, and does take
APPLICATIONS. 247
place, without being preceded by a reduction of external
temperature. The influence of external cold is inversely
proportional to the power of producing heat. The tempe-
rature of summer, although very high, is commonly very
inferior to the usual heat of the mammalia and birds. The
individuals in which the power of developing heat is feeble,
will, in summer, undergo refrigeration in proportion to the
feebleness of this power ; a circumstance which takes place
when they sleep. Observe, that their sleep, at this period,
is perfectly natural, since it is not determined by external
conditions, but is the necessary sequel to wakefulness.
Now, as the foregoing observation respects different genera
of mammalia, and the connection between the two pheno-
mena is in them exceedingly well marked, we may con-
clude, that the state of natural sleep is in general accom-
panied by a diminution in the power of producing heat. I
say, natural sleep, to indicate the most ordinary form of this
state, since modifications occur which change the relation.
It follows, as a consequence of the relation between the two
pheenomena, that the external causes of refrigeration must
take a stronger hold of the system in the state of sleep.
This explains why a damp and cold air, or a dry and piercing
air, which is borne without inconvenience when the indivi-
dual is awake, even without the aid of exercise, may be hurt-
ful during sleep. It may, in addition be remarked, that the
effect of exposure to cold during sleep, must necessarily vary
according to the power of producing heat.
Natural sleep, in many species of hybernating animals,
merits the denomination of lethargic sleep, from the remark-
able diminution of temperature, respiration, and circulation,
as well as of the external motions and excitability of the
senses. It differs in intensity according to individuals and
species. We have shewn the modification of the constitution
which has the greatest influence in this respect ; so that it
248 APPLICATIONS.
will be easily imagined, that changes of this kind may take
place in man, which will render his sleep lethargic, which
state, however, is not to be confounded with the effect of
disease or accident, such as privation of air or exposure to
noxious gases. Instances of the lethargic sleep here alluded
to, are to be found in medical works and are apt to be re-
garded as fabulous, but my own experience has convinced
me, that such cases do occur.
II. We have pointed out another order of phenomena,
observable in warm-blooded animals, in which the pro-
duction of heat is feeble. We have seen, that in the early
periods of life this constitution is common to all, that they
differ in the degree of energy of this power, so as to form
two groups in each class of the warm-blooded vertebrata.
Those which produce the least heat, are commonly found
in external circumstances which supply it, and which main-
tain their health ; but as soon as they are withdrawn from
them, they present the following series of symptoms ; a
lively sensation of cold, or an appreciable reduction of the
temperature of the body, with an acceleration of the circu-
lation and respiration. We have proved, that these symp-
toms arise from their not producing sufficient heat, and that
the external temperature does not supply this defect, al-
though they may be exposed to the warm air of spring or
summer.
The cold and shivering with which they are seized, not-
withstanding the warmth of the weather, and the accele-
rated motion of their respiration and circulation, present so
lively an image of the cold stage of an intermittent fever,
that we are led to admit a connexion between the two orders
of phenomena. We know that young animals present
these symptoms, because their power of producing heat is
APPLICATIONS. 249
feeble ; now, if this power in man undergoes diminution to
a sufficient degree, it is natural that the same phenomena
should follow. Let us now inquire, whether this function
in man is really thus altered in the cold stage. In the first
place the lively sensation of cold which he experiences is
a strong presumption in favour of that opinion. But there
are facts which clearly prove it. If, in this stage, the pa-
tient be subjected to cold affusion, such a degree of cold is
produced as may risk the loss of life. (See Dr. Currie on
Cold Affusion.) Now, the exposure to a relatively low tem-
perature, or the application of cold, is the very means em-
ployed in the course of this work to estimate the power of
producing heat in animals, we must, therefore, draw the
same conclusion from the employment of this means in the
present case.
Let us proceed now to the consideration of the tempera-
ture of the body. Respiration and circulation have no
longer their usual rhythm; their movements are accelerated.
From the facts detailed in Part IV. Chap. X., it may be
seen how accelerated respiration tends, more or less, to re-
establish the heat of the body, according as the means em-
ployed by the animal, in the state of health, for the pro-
duction of heat, are more or less feeble ; and that from
these extraordinary effects, result different states of the
temperature of the body ; that it may fall, or remain sta-
tionary, or rise above its original limit.
Let us take the favourable cases, or those in which the
acceleration of respiration and circulation re-produces suffi-
cient heat. If the movements which have developed it
have not been too much deranged, a time will arrive when
they will cease, inasmuch as the cause from which they
originated no longer exists, for the external warmth sup-
plies, in a great number of cases, as we have formerly
shewn, the deficiency in the production of heat.
250 APPLICATIONS.
It might be thought that the suspension of the stage of
which we have spoken must necessarily be momentary,
and that it cannot be prolonged beyond the time that is
necessary for the heat to be dissipated ; but we have shewn
in Part IV. Chap. IV., that the application of heat in those
cases, when the system does not develope it sufficiently,
produces effects which continue for a longer or shorter
period be}rond the time of their application, by increasing
the power of producing heat by the usual means pertaining
to health ; a distinction exceedingly important, for the
energy of those means is not measured in this case, by the
greater or less activity of the movements of inspiration and
circulation, as we have formerly shewn.
There will then be an intermission of greater or less
length, according to the degree to which the power of pro-
ducing heat shall have been injured.
The extreme cases of this intermission are found, on one
hand, in the restoration to health after a single attack ;
and on the other hand, in the J'ebres intermittentes algidcz,
described by Torti, in which this power is so impaired,
that the patient dies in the cold stage, at the end of
two or three accessions, if suitable remedies are not em-
ployed.
III. Since the application of external heat tends to re-ani-
mate the power of producing it, this means may be sub-
stituted-for the extraordinary efforts of the system, which
tend to the same object. It may be done either to prevent
them, or to shorten their duration.
This means will have more or less success, according to
the measure and mode of application, and the degree of
danger of the case. A striking example of it is to be seen
in the employment of the vapour-bath by M. Chomel, in a
APPLICATIONS. 251
case of intermittent fever. (Nouv. Joum. de Medicine, t, x.
p. 270.)
This mode of applying heat has a remarkable advantage
over many others, which will be readily understood on revert-
ing to the facts mentioned in Chap. VIII. of Part. IV.
Compare, for example, the effects of a liquid-bath and those
of a vapour-bath, both raised to a high temperature. The
heat in the latter case will be so much better borne as re-
course may be had to the vivifying action of the air. In
the liquid-bath, the action of the air is suppressed upon
almost the whole extent of the skin ; in the vapour-bath, on
the contrary, it is in communication with its whole sur-
face ; so that, ceteris paribus, the heat of steam will be borne
much longer than that of water.
In general, whatever be the temperature of liquid water,
one of the effects of the bath results from the limitation of
the communication of air with the system : hence, there
are many persons who experience a difficulty of breathing,
which essentially depends upon that cause. The same
may be said of the faintness which results from long con-
tinuance in the water, and it will readily be conceived, that
these effects will vary in different individuals, according as
the pulmonary respiration has a greater or smaller extent.
(See Chap. IV. Sect. II. Part. I.)
IV. In our inquiries into refrigeration in dry and humid
air, (Part IV. Chap. XIV. Sect. V.), we saw that these two
modes of refrigeration were different ; but that they tended,
in a great number of cases, to produce the same physical
effect, that is, the same reduction of the temperature of the
body. It is evident, that refrigeration in dry air is produced
by a greater evaporation ; but the mode of refrigeration in
humid air is not so clear. We observed, that philosophers
252 APPLICATIONS.
had not determined the relative quantities of heat ab-
stracted by dry air and by watery vapour ; but, whatever
be the result of such researches, it will not furnish all the
elements necessary for explaining the mode of refrigeration
of animals in humid air; for supposing it established, that
watery vapour abstracts more heat than dry air, it will be
conceived, indeed, that this mode of physical cooling may
be equivalent, in a great number of cases, to that which
results from a greater evaporation in dry air; but observa-
tion of the refrigeration in both cases shows that there is
another element. In the experiments cited above, in which
the reduction of the temperature of the body was the same
in both cases, or even greater in dry air, the animals ap-
peared to me to suffer more in humid air : I judged by the
shivering and the acceleration of respiration. I am aware
that such signs do not furnish rigorous tests; but they
have led me for some time back to pay peculiar attention
to the respective sensations, which dry and humid air pro-
duced on myself and others in cold weather.
Humid air, at an equal or even superior temperature,
produces a peculiar sensation of cold which differs, not in
its intensity, but in its nature. It is more profoundly felt,
and seems to penetrate the whole system, and particularly
disposes to paleness and shivering. By these characters, I
could not mistake a species of refrigeration, which consists
in the diminution of the power of producing heat.
In dry air, on the contrary, a sensation is experienced,
which is called a sharp cold, and which designates rather
the nature than the degree of the sensation ; moreover, it
is superficial, and when the reduction of temperature is not
too great, an increase of activity is experienced, the skin
reddens ; and in extreme cases, the limbs have a tendency
to stiffen, instead of yielding to their irregular and involun-
tary motions, which constitute shivering.
APPLICATIONS. 253
It may be seen, by this comparison, and by what we have
stated above, that damp cold must tend to produce, in in-
dividuals whose power of developing heat is rather feeble,
the series of actions which constitute the accession of an
intermittent fever, especially if they are exposed to that
influence during sleep. The confirmation of this will be
found in the study of medical topography. In a great
number of cases, these fevers are ascribed to marsh-mias-
mata in fine weather, but others occur in places and at
seasons at which the atmospheric constitution which we
have mentioned predominates.
V. We shall now speak of the effects of climate, some of
the elements of which subject will be found in Chap. V.
Part IV. relating to the influence of the seasons on the
production of heat.
Since there are, in this respect, a summer and a winter
constitution, we shall compare the former with that of the
inhabitants of warm climates, and the second with that of
the inhabitants of cold climates ; but, there will be this
difference, that the modification which characterizes the
summer constitution in our climate, will be much more
strongly marked in warm climates.
We have shewn, that here, in individuals whose consti-
tution is suited to the climate, this modification consists in a
diminution of the power of producing heat in summer, and
an increase in this respect in winter ; whence we conclude,
that this power will be feebler in the inhabitants of warm,
than in those of cold climates ; and that consequently,
when they change their climate, they must be, in general,
less capable of supporting the cold, than the natives of the
country.
If we were to judge from their sensations only, we should
frequently be led into error. Many individuals coming
254 APPLICATIONS.
from warm climates, are, at first, less sensible to the cold
than the natives of the country; which may be easily con-
ceived from the following- experiment. If in winter, in a
room of moderate temperature, the hand be held for some
time in iced water, and it be wiped afterwards, the sensation
of cold ceases gradually, and a feeling of heat succeeds, and
this sensation is so lively, that this hand would be thought
warmer than the other. But the illusion is destroyed when
they are applied to each other ; it then appears colder to the
touch. It is really so, as can be proved by the thermometer.
This is because the heat of the hand which had been cooled
returns quickly ; and the rapid increase in the development
of heat is accompanied by a sensation comparable to that
which is experienced when the heat is greater, but the de-
velopment stationary.
The natives of warm countries, who most readily adapt
themselves to the climate of cold regions, experience a rapid
increase of the power of developing heat; and the corres-
ponding sensation, just spoken of, will render them less
sensible to the impression of cold. This state, howrever,
does not last long ; it diminishes progressively, and scarcely
extends beyond two winters. Bat those whose constitution
does not adapt itself to a change of this kind, ot who do
not experience it to a sufficient degree, will be exposed to
all the inconvenience and all the danger, which result from
the action of too cold a temperature, if they do not take
the necessary means to guard against them.
On the other hand, the natives of cold countries, if they
continue to produce the quantity of heat adapted to their
own climate, when they remove to the equinoctial regions,
would have an excess of heat which would prove injurious
to them. The high temperature of this new climate, as
well as its duration, tends, perhaps, to diminish the ac-
APPLICATIONS. 255
tivity with which heat is produced ; but the measure of
that action is not always in proportion to the wants of the
system ; it is often too strong or too feeble, according to
the constitution of the individuals.
VI. They find, indeed, in the increase of evaporation from
great heat, if the air be not too humid, a cause which tem-
pers its effects ; but whose influence has been exaggerated,
when it has been supposed that it could effect an exact
compensation.
Conditions of evaporation may be conceived, which
counterbalance certain elevations of temperature ; but do
these usually take place in man ? Evaporation, all other
circumstances being the same, is in proportion to the sur-
face considered in reference to its extent, and its propor-
tion to the mass. Water contained in vessels, and that of
rivers and seas, is commonly below the temperature of the
air, from the evaporation which deprives it of heat ; and
although the difference of heat, dependent on evaporation
between the two media, is greater in summer than in winter,
it is always slight within the limits of the temperature of the
seasons and of the hygrometric variations of the air. But
as animals present a surface proportionally greater, their
bodies are better adapted to evaporation. They are,
in this respect, more like inanimate bodies, furnishing
vapour from the whole surface. If, for example, a sponge
be soaked in water so as to saturate it, and its temperature
be examined within the limits of the usual temperature of
the seasons, it is found to vary considerably with the heat of
the air, and to differ from it but a few degrees.
If now we wish to know what takes place in animals, we
must choose the species best adapted to this kind of obser-
vation.
256 APPLICATIONS.
There are none which lose more by evaporation than frogs,
and as their production of heat is extremely feeble, we shall
disregard it. Notwithstanding the difference of their losses
by evaporation in summer and in winter, their temperature
follows pretty closely the variations of that of the air. Much
more then will evaporation, which is less active in the other
animals, be insufficient to compensate for the elevation of
external temperature. It follows, that the equality of tem-
perature of warm-blooded animals in summer and in winter,
supposing the fact ascertained, is not wholly maintained by
evaporation. The cause which co-operates with it, to render
their heat constant or nearly free from variation in the
vicissitudes of the seasons, has been elsewhere examined.
(Part IV. Chap. V.)
VII. We are now led to a question not hitherto considered,
viz. Does the temperature of man and of warm-blooded
animals, vary according to the seasons ? It had generally
been believed, previously to the period of these investiga-
tions, that it was constant in the state of health and in
ordinary circumstances, notwithstanding the heat of sum-
mer and the cold of winter. In order to be informed on
this point, I tried a series of experiments upon the tempe-
rature of yellow-hammers and sparrows, at different periods
during the course of a year. They were tried upon a great
number of individuals recently taken, rather than on such
as might have had their constitutions modified by confine-
ment. I found that the averages of their temperature ran
progressively from the depth of winter to the height of sum-
mer, within the limits of two or three degrees cent. The
observations upon sparrows gave me the greatest difference.
The average was in February 40°.8 cent, or 1050,4 Fahr. ; in
April 42° cent, or 107°-6 Fahr. ; in July 43°.77 cent, or
APPLICATIONS. 257
1 10°-78 Fahr. I afterwards noticed the contrary course in
the decline of the year.
Hence I judged, that man also would experience varia-
tions of temperature under the influence of the seasons and
of the change of climate, if not to the same extent, at least
within appreciable limits. Dr. John Davy, on his return
from Ceylon, informed me, that the temperature of the inha-
bitants of that island, was higher than ours by one or two
degrees of Fahrenheit, and that he had observed a similar
change in the same individuals before their departure and
after their arrival.
VIII. The increase of temperature of which man is sus-
ceptible in disease, without deriving it from surrounding
heat, is much more considerable. Dr. Prevost of Geneva
communicated to me a most remarkable instance of this.
One of his patients, a boy of twelve years, was affected with
tetanus, accompanied by an extraordinary development of
heat. To determine the extent, he placed a thermometer
in the axilla; and found it 35° R. equal to 430,75 cent, or
11075 Fahr. Supposing that the original temperature of
the child was 360,756 cent, or 98-2 Fahr., which is above
the average for that age, here will be an elevation of 7° cent,
or 12i Fahr.
IX. It will be admitted, that it is important to moderate the
excess of heat, not only in such extreme cases, but in others
in which it is not so high, whether it proceeds from without
or from within. There are circumstances in which heat
increases by a salutary effort of nature, and we have given
examples of it above. Even then these efforts are fre-
quently irregular, and art must interfere to moderate
them. Often the excessive production of heat has no sa-
s
258 APPLICATIONS.
lutary tendency when it is necessarily still more important
to moderate it.
The most powerful means furnished by external agents,
consists in the application of water of a suitable tempera-
ture. It is evident in the first place, that it tends, by a
physical action, to reduce the temperature of the body. It
is true, that its employment cannot be of long continuance ;
but even when only a temporary reduction is obtained, this
respite will itself be very advantageous ; and the repetition
of the means, applied according to the exigence of the case,
will multiply the intervals. But it produces another effect,
which we have mentioned elsewhere. Cold, whatever be
its nature, if it be sufficiently marked, tends to diminish the
activity with which heat is developed, and damp cold is, of
all external means of refrigeration, the best adapted to
bring about that change. This serves to explain the ad-
vantage which has frequently been derived from the use of
cold water, under the varied forms of baths, douches, and
affusions, in cases of the extraordinary development of
heat.
X. When these means are not considered expedient, the
other external methods of refrigeration, if they have a less
speedy and powerful effect, afford some compensation in
the continuance which they admit of. Thus, the sponging
of various parts of the body, although they be wiped imme-
diately, and whatever be the temperature of the water, pro-
vided it be not excessively hot, produces from the moistened
surface a more abundant evaporation, whence results a sa-
lutary refreshment which may be continued indefinitely.
XI. When care is taken to maintain the adequate ventila-
tion of an apartment, this method of refrigeration depends
not only on the quantity of heat abstracted by contact, but
APPLICATIONS. 259
also on the increase of evaporation. Few results of experi-
ments have struck me more forcibly than the difference of
perspiration by evaporation in a calm air, and in one that
is slightly agitated.
XII. If perspiration by evaporation produces a salutary
refrigeration, it produces also other effects, which, when
excessive, may in many instances, be very injurious.
We have seen, in the experiments upon fishes, that by the
perspiration from the gills and skin, either of these organs
may become dry, although the body should lose nothing of
it's weight, on account of the absorption of the water in
contact with the rest of the surface. (Part II. Chap. II.
Sect. V.)
The intensity of this effect, capable of causing the death
of these animals, directed my attention to circumstances, in
which considerable evaporation from the surface of the lungs
or skin, would be injurious toman.
One of the situations in which perspiration by evapora-
tion is considerably increased, is found in the higher re-
gions of the atmosphere, upon high mountains. Many per-
sons experience in such situations distress and anxiety in
the chest, which they refer only to the rarefaction of the
air limiting the extent of respiration. This cause may
have its share in the effects; but that which I have just
pointed out, acts in a more extensive and more general
manner.
We may thus distinguish their respective influence. The
rarefaction of the air in high situations is accompanied, in
fine weather, by a considerable dryness ; and hence such
an increase of perspiration by evaporation, not only from the
skin, but also from the lungs, that the loss of water suffered
by those organs will produce a feeling of distress in the chest,
proportionate to the desiccation.
s 2
260 APPLICATIONS.
If, as frequently happens upon mountains, the weather
change quickly, loading the air with humidity, the eva-
poration becomes moderate, and the distress diminishes, or
ceases entirely. If it still continue, it is owing to the ra-
refaction of the air. The effect of evaporation is felt the
first, and that which is owing to a want of air comes long-
after : it requires even a much greater height to produce it
than one would be inclined to believe when the two sensa-
tions are confounded.
Thirst is a symptom which attends the ascent of mountains.
It is sometimes intense, when it cannot be ascribed to the
fatigue of exercise. It is only momentarily satisfied, even
by abundant and often repeated draughts. But if the
air becomes charged with moisture, the thirst at the same
time disappears. Here is an example perfectly analogous
to that which we have elsewhere mentioned as the effect of
a partial desiccation, although the body may be furnished
with a sufficient quantity of water to prevent its losing its
total weight, the distribution of the liquid to the different
parts not being in sufficient proportion to repair local loss.
It is obvious that this influence will be very differently felt
by different individuals, according to the state of the
lungs.
XIII. There are great differences in the effects arising
from the rarefaction of the air, depending on variety of con-
stitution. The symptoms proceeding from this cause are to
be distinguished from those of evaporation, by placing animals
in conditions in which the influence of this last cause may
be disregarded, as in the large receiver of an air-pump. If
the vacuum be quickly made, the rarefaction acts on the
respiration before evaporation or the alteration of the pro-
portions of the air can produce sensible effects. We see
APPLICATIONS. 261
weakness of the body and acceleration of respiration in-
ducing hurry of the circulation. These symptoms are not
in this case complicated, as in the ascent of mountains,
with those which proceed from excessive fatigue and other
causes.
We have now to determine, if those symptoms are really
owing to the rarefaction of the air which limits respiration.
This fluid cannot be rarefied in the air-pump without at the
same time diminishing its elasticity, which is equivalent to a
diminution of pressure, and the phsenomena which the ani-
mals present may arise from either cause, or from both com-
bined. Let us suppose in the first place, that each has its
peculiar phenomena, and let us see what results from limited
respiration in the cases in which there is no diminution of
pressure. If a warm-blooded animal is placed in a limited
quantity of air, whether we leave the carbonic acid which it
produces, or absorb it, taking care to maintain the same
pressure, the general effects observed are the same as we
have referred to the rarefaction of the air. Now, as these
various means act by limiting respiration, the common
effects ought to be ascribed to that cause. Even though
the diminution of pressure were to act in the same way, it
is still true to say, that the class of phsenomena which we
have described, are owing to the rarefaction of the air : only
their intensity would be increased by the concurrence of
another cause.
There is a symptom connected with respiration limited
by rarefaction of the air, which appears to me not to have
attracted attention, or not to have been looked at in this
point of view : I mean the disposition to vomit. In order to
judge of it, it is advisable to choose those warm-blooded
animals, in which vomiting is most easily excited : such
as birds of small species, as yellow-hammers, sparrows,
262 APPLICATIONS.
fringillas, &c. The rarefaction of the air, when carried far
enough, produces this effect on a great number of indivi-
duals, and what proves that it is referable to limited respi-
ration is, that it takes place in whatever manner the extent
of this function may be limited by other modifications of
the air.
It is easy now to refer to their respective causes several
phenomena which have been observed in man when he is
elevated to great heights, whether on mountains or in bal-
loons. If the disposition to vomiting has been but seldom
observed in these circumstances, there are, nevertheless,
persons who have experienced it, and I have been convinced
by their statements, that it depended on the same condition
as that which produced it in the animals submitted to expe-
riment. I have alluded to this circumstance, not to add to
the number of symptoms which may manifest themselves,
but to connect it with a great number of others, in which
respiration is limited in different ways, as in acute or chro-
nic congestions in the lungs, when the disposition to vomit-
ing and vomiting itself, are frequently symptoms arising
from the diminution of the communication of the system
with the air.
XIV. Species and individuals vary very much in the power
of supporting limited respiration. The extent to which the
rarefaction of the air can be carried, without sensibly dis-
tressing the respiration of a great number of the superior
animals and of men, is truly surprising ; but the limits at
which extreme rarefaction produces effects almost as rapid
as those of the absolute privation of this fluid, are suffi-
ciently near to allow of few differences in this respect in
warm-blooded animals. The pressure at which the yellow-
hammers, which I subjected to the experiment, were on the
APPLICATIONS. 263
point of dying, corresponds, taking the average, to 5*31
inches of the barometer, and the average for the guinea-
pigs to 3'58 inches. I quote the species which presented
the extreme results.
XV. Facts connected with an excessive evaporation from
the lungs, may be observed in other places besides elevated re-
gions. In winter, when during a very sharp cold, an apart-
ment is warmed by means of a stove, many persons ex-
perience a painful sensation in the chest. The air, in a
frost, contains scarcely any watery vapour, and the heat of
the stove by raising the temperature of the air increases its
capacity for vapour, so that, at an equal temperature, the
quantity of liquid dissipated by evaporation is much greater
than in summer. It is an old custom to place upon the
stove a vessel containing water, in order to remedy the
uneasiness to which we have alluded ; but this is commonly
insufficient, from an incomplete application of the principle
upon which its utility is founded. It would be necessary
to produce a more abundant evaporation, in order to bring
the air to the degree of humidity which renders it suitable
to our constitution.
In the situation just pointed out, I suppose the heat
moderate, and even then it may appear excessive, because
the uneasiness alluded to is attributed to that cause.
In arid districts, effects are likewise ascribed to the heat
of the air and of the wind, which arise in a great degree
from the evaporation occasioned by the dryness of the at-
mosphere. Dr. Knox, who travelled in the interior of
Africa, to the north of the Cape of Good Hope, has related
to me facts which justify this opinion.
XVI. It is known that in an agitated atmosphere, not ex-
tremely humid, evaporation, generally considered, maybe as
264 APPLICATIONS.
great as in a calm and dry air; but, supposing two conditions
of the atmosphere, in which the effects of motion in the one
would equal those of dryness in the other, their respective
influence upon perspiration by evaporation would not be
the same. Air in motion only acts upon exposed surfaces,
as the integuments of the body ; those of the lungs are
sheltered, and notwithstanding their communication with
the atmosphere, the agitation of the air has but a slight
share in the quantity of vapour which they furnish. This
consideration will serve to determine the choice of suitable
places for the residence of delicate persons. Those to whom
the increase of evaporation from the lungs is injurious,
ought to prefer an atmosphere less dry, but slightly agi-
tated, when it is important to obtain an agreeable fresh-
ness.
XVII. In a great number of acute diseases, the skin, and a
part of the air passages manifestly become dry. Now, after
seeing the fatal effects which may be produced upon ani-
mals by the desiccation of either organ, the necessity of re-
medying it as much as possible, must be strongly felt. We
have seen how insufficient drinking; is : the exhalation of
watery vapour to which recourse is sometimes had, pro-
duces only temporary relief, and in many cases its cure is
impossible. If the atmosphere of the patient be rendered
humid, by maintaining near him a sufficient evaporation of
water, he will continually and without effort, breathe a
vapour, which will not only arrest the desiccation of the
respiratory organs, but will also tend to put a stop to that
condition, by means of the absorption of which that vapour
is susceptible. (Part IV. Chap. XIII.)
More active measures are necessary for the skin, in order
to soak it with water to a greater or less extent, and after-
wards dry the surface ; a precaution in general necessary
APPLICATIONS. 265
in order to procure for the patient, by immediate contact,
the advantage of the vivifying influence peculiar to atmo-
spheric air, or in other words, of cutaneous respiration.
Such measures adopted with assiduity and discernment,
would contribute to diminish the mortality in this kind of
diseases.
XVIII. Very important considerations result from the dif-
ference of constitution at different periods of life. If the at-
tentions which children require in climates and seasons little
favourable to the preservation of their existence, were gene-
rally understood and put in practice, it would considerably
reduce one of the most powerful sources of mortality affecting
that age in our climate. It is not confined to children whom
the misery of their parents cannot guard from the rigor of
the weather, but it operates to a great extent, without
being either perceived or suspected, in families enjoying
affluence, and in which it is believed, that the necessary
precautions are taken, because cold being relative, it is diffi-
cult from our own feelings to judge of its effects on others,
and because it does not always manifest itself by determi-
nate and uniform sensations. They do not feel the cold, but
they have an uneasiness or an indisposition which arises
from it ; their constitution becomes deteriorated by passing
through the alternations of health and disease, and they
sink under the action of an unknown cause. It is the more
likely to be unknown, because the injurious effects of cold
do not always manifest themselves during or immediately
after its application. The changes are at first insensible ;
they increase by the repetition of the impression or by its
long duration ; and the constitution is altered without the
effect being suspected.
There is a general precaution which would tend to pre-
vent these effects, and which it is sufficient here merely to
266 APPLICATIONS.
point out. It is to watch the changes which may come on
during health at the decline of the year, and in the course
of the cold season ; and, however little it may be liable to
derangement, to preserve heat by a warmer clothing. If
the clothing is adapted to the wants of the individual, it
will contribute powerfully to guard him from the alterations
dependant on the influence of the season ; he will enjoy at
the same time the advantage of being exposed to the open
air in conditions of the atmosphere which would not injure
his health.
In countries in which the cold is excessive, the feelings
so strongly impress upon the inhabitants the necessity of
guarding their children against it, that the particular care
which they take renders this cause of mortality, perhaps,
less in them than it is in temperate countries. It is suffi-
cient, then, to feel this necessity, in order to find suitable
means to meet it. These means are referable to several
heads : 1, The modifications of the air to adapt it to the
system. 2, The preservation of the natural heat by clothing.
3, The changes to be produced in the constitution of the in-
dividual, in order to increase his power of developing heat,
so as to extend the limits of the atmospheric variations to
which he may be exposed without danger.
People are frequently dissuaded from the use of warm
clothing, and the external application of heat under the
form of baths, by the idea that they may induce delicacy
and greater sensibility to cold. This opinion is undoubtedly
founded upon very general experience, and I think that the
observations which I have made on this subject do not
weaken it; but other facts equally well attested tend to
circumscribe it within just limits, and shew us that when
the system does not develop sufficient heat, the means
which we have just pointed out contribute to increase the
power of producing it.
APPLICATIONS. 267
Although the want of it is actually felt, the use of warm
clothing is often declined from the wish to reserve it for an
advanced age. But it frequently happens, that this very
precaution is the cause of preventing that age from being
attained.
The employment of the warm bath is dreaded because
water enervates, but this effect is obviated by reducing the
duration of the bath, and thus making the application of
heat predominate.
XIX. It is well known to be difficult to rear children that
are born long before the full time, such as those of about the
sixth month of pregnancy. In general, the care which is em-
ployed for preserving the heat by means of clothing would
be insufficient, as I have ascertained in the case of young
animals, which are born in a similarly imperfect state.
There ought to be a continued external application of heat
until the body has acquired sufficient development. What
I have said of childhood in general is applicable to every
period of life, when the constitution from any cause approxi-
mates to the modification in question.
Although the condition of hospitals has been considerably
improved, and although it might be easily shewn that a
sensible diminution of mortality has been the result, yet a
great number of these institutions are still susceptible of
amelioration in respect to their temperature in winter.
St. Bartholomew's Hospital in London, may be mentioned
as an example of the judicious means employed to combine
this indication with others which have reference to the sa-
lubrity of the air.
XX. Persons are often led to attribute to suppression of
perspiration, effects which principally result from the action
of cold upon the system ; and it sometimes happens, that
268 APPLICATIONS.
the perspiration is supposed to be suppressed in cases when
it is really increased. We have already shewn that it is only
the sweat which can really be suppressed ; which, however,
does not necessarily imply the suppression of transudation.
It is then diminished so far as to be insensible, but it may
continue to take place.
It is not however indifferent to the system, whether the
same loss in weight is occasioned principally by evaporation,
or by transudation. In the first case, the liquid dissipated
is nearly pure water; in the second, transudation being a
secretory process, the water carries with it a notable propor-
tion of animal matter.
Thus, considering the effects only as connected with the
proportions of liquids and solids, perspiration by evaporation
merely bears on the diminution of water in general, and
tends to the partial desiccation of some organs important to
life. Transudation, at the same time that it diminishes
the total mass of water, diminishes also that of animal
matter, and instead of drying the organ which is the seat
of it, tends on the contrary to moisten it.
Hence, in the comparison of the effects of losses equal
in weight by each process, it may be imagined, when they
are considerable, how much more that, by sweat, ought to
weaken.
The absorption of water equivalent in weight, may, nearly
or quite, repair the loss occasioned from perspiration by
evaporation ; but it would be far from repairing a loss of
equal weight occasioned by sweat.
These two modes of perspiration differ also in their pro-
gress. Perspiration by evaporation has a tendency to dimi-
nution, in equal and successive periods ; transudation or
sweat, being determined by heat, in favourable circum-
tances, tends, on the contrary, to uniformity within certain
limits.
APPLICATIONS. 269
There is this other difference, that when the physical
conditions which increase perspiration by evaporation cease,
that process diminishes in proportion. This is not the case
with transudation occasioned by a very high temperature.
This continues to a very great degree after the application,
if the heat has ceased.
XXI. When, independently of the particular modifications
of the matter perspired, we wish to know the mean quantity
which an individual loses by this means in the course of a
day, it is not immediately obvious what assistance can be
derived from the statical observations which have been
made on this subject. Indeed the results vary, according
to the persons who have stated them, within very distant
limits, from 27 to 60 ounces per day. These differences
are often attributed to differences in the constitution of the
individuals, from age, climate, and unknown causes. But
it happens here, as on many other occasions, that the facts,
although they arise from a number of causes, which, it would
appear, must occasion infinite variations, are, however, ca-
pable of presenting a result so uniform as to admit of its
being; foreseen.
In order to find a result in the case of perspiration which
will approximate to this regularity, it is necessary to pay
attention to a relation which exhibits itself in all the sta-
tical researches on the perspiration of man, continued for a
long course of time.
On comparing the daily average of meats and drinks
during the course of a year, with the sum of all the losses
by perspiration, and the alvine and urinary evacuations, it
will be seen, that they are nearly the same. It is then of
importance to examine the proportion of these evacuations
to each other. The proportion of urine to perspiration va-
ries in the tables of Robinson and others, but on taking the
270 APPLICATIONS.
average of these proportions, it approximates remarkably to
equality, and is found to be : : 1 : 1*08.
The alvine evacuation forms but a small portion of the
total loss. The mean of all the quantities eliminated by
this way, in the tables to which I have alluded, is four
ounces. By substracting this quantity from the sum of the
meats and drinks, and taking the half of the remainder, we
shall have an approximate result of the mean product of
the perspiration of a day in the course of the year.
In order to judge of the degree of approximation which
may be attained, by making use of these data with the
mere knowledge of the sum of meats and drinks, we give
the comparison of the results furnished by experience
with those deduced by calculation from the preceding
proportions.
Mean losses by perspiration in a day.
Robinson. Robinson. Keill. Rye. Lining.
42 yrs. 64-5 yrs. 39yrs. 42yrs. 40 yrs.
By observation. 45 oz. 27 oz. 30 oz. 56oz. 60 oz.
By calculation. 41 27 35 46 62
It may be seen from the tables of these authors, that the
vicissitudes of heat and cold, when well marked, as in the
countries in which they resided, tend to occasion a pre-
dominance of perspiration over urine in warm weather, and
the contrary in cold. The observations of Rye, are the
only exceptions ; for his mean perspiration, even in winter,
exceeds the urine, although it approaches to an equality.
The rule then which we have given for estimating the
mean perspiration, is applicable only to the climates of
which we have just spoken.
In warm climates it is probable, that the average of per-
APPLICATIONS. 271
spiration for the year would sensibly exceed the mean of
urine. The observations of Sanctorius, though incomplete,
indicate that this is the case in Italy ; and a fortiori, will
it be so in hotter countries.
XXII. We have formerly considered the effects which
various modifications of air produce upon perspiration ;
we shall now examine certain effects of the same con-
ditions of the atmosphere upon respiration.
The slight agitation of the atmosphere, when its hygrome-
tric state and temperature are adapted to the system, pro-
duces such a feeling of well-being, that the chest dilates in
consequence, and admits a large proportion of air. This is
a phenomenon which has particularly attracted my atten-
tion, and which I have observed, wherever, from the space
being extended, the air admitted a greater variety of move-
ments. I have frequently had occasion to ascertain, that
persons who have what is called delicate lungs, owe in a
great degree, the difficulty and oppression which they feel,
to the smallness of their apartments, a difficulty which de-
creases on going into a large room, or into the open air.
Whatever difference of purity may be attributed to the
air of small and of large rooms, of narrow and of wide
streets, of town and of country, the degree of agitation of
the air has the most marked influence on the extent to
which the chest dilates itself : the agreeable sensation which
is experienced on breathing in the country is principally
due to that cause.
We cannot be too careful in distinguishing the cases in
which difficulty of breathing arises from a want of extent in
the movements of the chest, from those in which it is owing
to a mechanical obstruction. The means of remedying the
first, are more numerous and more powerful than may be
272
APPLICATIONS.
imagined ; and often even when organic change exists, at-
tention to external circumstances may afford much relief.
XXII I . There are modification s of structure, connected wi th
respiration and circulation, which scarcely manifest symp-
toms of disease, except under certain external circumstances.
It would be as vain to attempt, at least, in the present state
of our knowledge, to reduce some of these modifications of
structure to ordinary conditions, as to desire to change
those which characterize a species. The art consists then
in suiting; the external circumstances to this state of orga-
nization. The limits within which persons so constituted
can enjoy life, are more confined than in other persons ; but
the knowledge of these limits serves to procure for them
health and even longevity. The principles deduced from
the observations and experiments detailed in this work are
such as to furnish applications of this kind.
In connexion with these modifications of structure, to
which we have just alluded, I would refer to the 9th Chap-
ter, Part IV., which treats of the effects of temperature
upon the functions of respiration and circulation ; and also
notice a series of clinical observations which serve as illus-
trations of these principles. We owe them to M. Rostan,
who has recorded them in his interesting memoir, Sur
VAsthme des Vieillards.
He has found, that the affection which he calls by this
name, corresponds to certain organic affections of the heart,
the great vessels, or the lungs. These cases are extremely
numerous in the Hospice de la Salpitriere, where he every
year sees persons labouring under it, who enjoy, in general,
pretty good health in fine weather ; but who, when the heat
declines in autumn and winter, come in numbers to the
wards of the hospital, with the palpitations and the labori-
ous respiration which characterize the disease.
APPLICATIONS. 273
XXIV. When a mechanical obstacle, such as an engorged
state of the lungs, prevents the entrance of a sufficient quan-
tity of air, there is another order of considerations relative to
those diseases, which has been suggested to me by my re-
searches upon animals. The great number of cases in
which the engorgement of the lungs diminishes the com-
munication with the air, directed my attention to the cir-
cumstances which determine the power of supporting
limited respiration. The reader will find facts relating to
this subject in Part IV. Chap. VIII. ; but we shall look
upon it here in another point of view. It has been long
known, that the young mammalia sink less rapidly than
adults, when they are entirely deprived of air. But it is
also known, that this difference ceases soon after birth, and
even that it is very slight between a very great number of
new-born mammalia and adults. (See Part III. Chap. IV.)
It is not the same with limited respiration. Long after the
period at which the state of asphyxia is scarcely of longer
duration in young animals than in adults, I ascertained
that the former much better support the effects of limited
respiration. In the repeated experiments which I have
made upon the respiration of adults, in limited quantities of
air, in no instance, after leaving them there until they sunk,
have they been restored to life by exposure to the open air.
But several young birds which had altered an equal quan-
tity of air, so as no longer to give signs of life, recovered
after they were taken out, though I have never observed
this when they were entirely deprived of the contact of air
as in the case of submersion.
By limiting the action of the air in a different way, it will
be seen in a very sensible manner how much better the con-
stitution of young animals is adapted for supporting respi-
ration, than that of adults. If the chest of an adult is
widely opened, the lungs collapse, and the external motions
T
959
APPLICATIONS.
cease almost as rapidly as if the animal were immersed in
water. Meantime the air which is in contact with the sur-
face of the body, and with the lungs, visibly maintains a
respiratory action, since the heart continues to beat, and
the blood becomes scarlet at the surface of the lungs.
The same operation was performed upon kittens, one or
two days old, some of which were deprived of the contact
of the air by putting them under water : the others were
exposed to the open air. The experiments were performed
at the temperature of 20° cent, or 68° Fahr., that most
favourable to the duration of life under water. The mean
term of the life of the kittens in water was 38 minutes, that
of those exposed to the air was lh. 2m. It is to be observed*
that in this circumstance, as in others, we have judged of
life by external acts only, and not by the feeble motions
which go on within, when these have ceased.
Hence it follows, that children in whom respiration may
be limited by engorgement of the lungs, will, all other cir-
cumstances being the same, be less in danger than adults,
when communication with the atmosphere may be limited
in like manner and to the same degree ; and as the disturb-
ance of the system, marked by the acceleration of respira-
tion, circulation, &c, is so much the greater as the want
of air is more pressing, the symptoms of pneumonia will be
more intense in adults, in cases in which the relative extent
of disease is equally limited.
The facts formerly detailed prove, that the principal
characteristic which distinguishes warm-blooded animals,
at different periods, from their birth to adult age, is derived
from their power of producing heat. We have also shewn
the connexion between this power, and that of supporting
the total privation of air. It is the same with limited re-
spiration. As we have shewn, that adults may differ much
in their power of developing heat, we may conclude, that
APPLICATIONS. 275
they differ also in their power of supporting diminished re-
spiration.
XXV. These considerations lead us farther. If an in-
dividual is affected with pneumonia, so far as to endanger
his life by diminished communication with the air, the most
urgent indication is to employ the best means to bring back
his constitution to that state which would enable him to
support this limited respiration. Now, although this has
not been kept in view, in the treatment at all times adopted
in this disease, the indication has, however, been fulfilled.
In whatever manner the blood contributes to the production
of heat, we cannot doubt that it does exercise a considerable
influence over it. A small abstraction of blood cannot in
this case produce a sensible effect, but a sufficient evacua-
tion could not fail to diminish the power of producing heat ;
and keep it within the limits compatible with life. The
more serious the case, the greater ought to be the abstrac-
tion of blood.
XXVI. The present state of our knowledge respecting
the blood, presents new views which are intimately con-
nected with physiology and pathology. MM. Prevost and
Dumas, who have analyzed the blood of a great number of
species of the cold-blooded vertebrata, and of warm-blooded
animals, have found, that the proportion of water was the
greatest in the cold-blooded vertebrata, less in mammalia,
and at the minimum in birds ; or, reciprocally, that the re-
lative number of globules (particles) increased in the order
of the preceding classes. It is evident, that if we could
change the proportion between the water and the globules,
(particles) we should have another means tending to ap-
proximate the constitution of the mammalia to that of the
cold-blooded vertebrata.
t 2
276 APPLICATIONS.
Suppose that we have recourse to the injection of water
to effect this change, it will then be found, by what we
have formerly established respecting absorption, within
what narrow limits this change will be confined.
In the experiments upon animals, the best adapted for
manifesting the effects of the absorption of water, we saw
that there was a point of saturation which they do not pass
so long as their constitution does not experience certain
changes, however multiplied and prolonged may be the
contact of the water with the absor'.ing surface. The point
of saturation at which absorption ceases, is determined by
the maximum of liquid which the body can contain in the
natural state.
Let us now suppose, that the body is at its point of sa-
turation, absorption will cease only for the moment; for the
body will rapidly recede from the point of saturation, by the
losses which perspiration continually occasions, without
mentioning other excretions. Absorption will take place
in consequence, as we have shewn elsewhere.
The body will then tend to maintain itself at the point of
saturation ; but it will not maintain itself exactly at it: —
it will undergo fluctuations dependent on excretion and
absorption, and so long as food repairs the losses of animal
matter, the injection of water, however abundant, will have
little effect upon the proportion of this fluid to the globules
(particles) of blood.
If strict abstinence is observed, as in acute diseases, the
losses of animal matter not being repaired, the proportion
of globules necessarily diminishes, but this change is too
slow for the most severe cases.
The most prompt and most efficacious means of effecting
this change, consists in the abstraction of blood. Bleed-
ing, at first affects only the quantity of blood, and not the
proportion of its constituent parts ; but the depletion, ac-
APPLICATIONS. 277
cording to its extent, has removed the body from its point
of saturation ; absorption is increased in consequence, and
is then principally operating upon the water in contact with
the absorbing surfaces. The body may thus be restored to
its original weight, or very nearly so. It follows, that the
number of globules being diminished by the abstraction of
blood, and absorption supplying this loss by water, which
brings scarcely anything with it but the materials which it
holds in solution, the proportions of the blood in relation to
the water and the globules may change very rapidly, and
to a great extent compatibly with life.
If these deductions should leave any doubt respecting
the justness of the conclusion, it may be removed by direct
observation. Prevost and Dumas have proved, that the
blood drawn at a suitable interval, after previous bleeding,
presents a diminution in the proportion of globules.
I refer those who wish further to examine the subject, to
the memoir read by Magendie in 1820, on the mechanism
of absorption in animals with red and warm blood, {Journal
de Physiologic, torn. 1.) and also to Fodera's Experimental
Researches on Absorption and Exhalation.
When it is considered, that the cold-blooded vertebrata
differ from warm-blooded animals, not only in their power
of supporting limited respiration, but also in their resistance
to a multitude of other deleterious influences, it will be ac-
knowledged, that the plan of treatment which tends to pro-
duce an approximation to their constitution, in individuals
of superior classes, within the limits which their organiza-
tion admits, would put, them also, in the most favourable
conditions for escaping the same causes of destruction.
XXVII. We have seen, by the comparison of the blood
of different species, and the action of some means adapted
to modify this fluid in a determinate manner, how this
278 APPLICATIONS.
change can be effected. But this change has limits which
depend not only on the proportions of water and of globules,
but also on the nature of those globules themselves. They
differ, as we have already pointed out, from the researches
of Prevostand Dumas, according to classes and species, by
their form and their dimensions. No means with which
we are acquainted can effect alterations of this kind ; and
even, if we had them at our controul, their employment
might, perhaps, be not salutary, but fatal. These physi-
ologists have, indeed, been able to restore life and health
to animals, which appeared deprived of them through loss
of blood, by infusing into them blood having globules of the
same kind. But when they endeavoured to produce the
same effect with blood, the globules of which were of a
different kind, they succeeded so much the worse, as the
form and dimensions of these globules were further removed
from those of the globules of the blood of the individual sub-
jected to the experiment, and in cases of extreme difference,
although at first they re-animated the animal, they caused
horrible convulsions, quickly followed by death.
XXVIII. There are other characters, besides the dimen-
sions and the form of the globules, which have intimate re-
lations with the mode of vitality. They are derived in the
first place, from the apparent change which the globules
undergo in their colour ; a change common to all the verte-
brata. The globules are composed of a central white
nucleus, and of an envelope of a red colour* ; which alone
undergoes that modification which makes the particles pass
from a dull red to a bright vermillion ; and according to the
shade, they exert upon the phenomena of life an action no
less powerful than that which is derived from their form and
* See the correction of this view in the additional matter subjoined to the
Appendix.
APPLICATIONS. 279
dimensions. Their communication with the air determines
the extent of this change. A great number of facts record-
ed in this work are referable to it, some immediately, others
in a more remote manner, and they lead to the determi-
nation of other facts which the state of science places within
reach ; such especially as those which I have given relat-
ing to the alterations of air from respiration in Part IV.
Chap. XVI.
As these facts lead us to consider the oxygen which dis-
appears in respiration as really absorbed, we should now
follow its traces in the system, and establish the nature of
its combinations and of its actions. Here commences a
new order of researches. The same is the case with the
azote absorbed in the act of respiration, and the sources from
whence the exhalation of this gas and of carbonic acid is
derived : it is also the limit prescribed to this work ; but I
cannot terminate without pointing out how this order of
researches necessarily connects itself with the recent dis-
coveries on the composition of the blood, and the action of
the nervous system.
XXIX. We have considered the composition of the blood
only in relation to the water and globules ; but these are
not its only constituents. It is known that the limpid por-
tion is not pure water ; it contains in solution, among
other substances, albumen, salts, &c, and forms what is
called serum.
It is sufficient to draw blood from a living animal and
analyse it by the known means, to find there several of these
substances and determine their proportions. But if we
confined ourselves to this method, we should not discover
other constituent parts, the knowledge of which throws a
great light, not only on the composition of this fluid, but
also on the secretory functions. The differences which had
280 APPLICATIONS.
been observed between the immediate constituents of the
blood, and those of several other fluids in the system, had
caused them to be attributed to a different origin. Thus,
urea, the characteristic principle of urine, not being found
in the blood by known methods, it had been concluded,
with much apparent reason, that it did not exist in it, and
that it owed its formation to the kidneys. This opinion has
been universally adopted since the discovery of urea. Pre-
vost and Dumas thought, that this secretion might be re-
garded in two different lights, either the one which I have
just mentioned, or the following. They discovered the means
of deciding the question. They supposed that the kidneys,
instead of forming urea with the materials derived from the
blood, might give passage to it according as the blood fur-
nished them with this principle already formed. In this
case, it would be found in so small a quantity in the blood
drawn from the animal in the natural state, that it could
not be recognized by the ordinary means of chemical ana-
lysis • but these means would be sufficient, if, on the sup-
position that the kidneys give passage to this principle,
this passage were arrested. The extirpation of the kidneys,
with the necessary precautions, must fulfil this indication,
and then the urea, accumulating in the blood, would be-
come manifest by the ordinary methods of analysis. They
thus discovered in the urea a new principle in the blood
which they found in great quantity, and made us acquainted
with one of the principal secretions of the body in a new
point of view.
The fact just mentioned relates to the state of health ;
but there are others which constitute new relations between
the composition of the blood in the state of disease, and
the secretions which depend upon it. Children are subject
to a disease characterized by induration of the cellular tissue.
Chevreul, on analyzing the fluid secreted by this tissue,
APPLICATIONS. 281
found that it contained a substance which coagulates whilst
cold. He has also recognized its existence in the blood of
the same patients, and this in great proportion. It is the
same with the colouring matter of jaundice which frequently
accompanies this disease. Thus, morbid secretions are
connected with the constitution of the blood, by the co-
existence of the same principles in this and in the other
fluids.
XXX. These relations will doubtless be multiplied.
Since a great number of the immediate principles of the
organs and of the secretions, must now be referred to the
blood, it is natural to inquire how they come to make part
of it. It is known that the digestive system furnishes a
great number of them ; but the origin of all of them cannot
be referred to that source.
Although the course which is taken by the oxygen which
disappears in respiration has not been discovered, it is a
necessary consequence of the absorption of any substance,
that it passes in a greater or less proportion into the blood.
Here then is evidently one source of the changes in this
fluid, which may give rise to some of the immediate prin-
ciples which constitute it. It remains for further researches
to determine them. Enquiries of this nature appear in-
timately connected with the study of the nervous influence,
especially since the labours of Dr. Wilson Philip have made
us acquainted with the share taken by the nervous system,
in converting the food carried into the stomach into chyle.
The accuracy of the Doctor's researches have been verified
by the experiments of Breschet, Vavasseur, and of my bro-
ther Henry Edwards. {Arch. gen. de Med. Aout, 1823,
p. 485.)
XXXI. We find, in the changes which the blood can
282 APPLICATIONS.
undergo as to its composition, a fertile source of the changes
in the mode of vitality. It would appear at first, that it is
only through this medium that we can act on the nervous
system, in order to modify its action so as to change the
constitution of individuals ; on account of the extent in
which this fluid can vary, and of the apparent immutability
of the nervous system in its form and structure.
It is evident, that the dimensions and proportions of that
system have limits assigned by nature to the modifications
which their vitality can undergo ; it is, however, sus-
ceptible of considerable changes, not discernible by in-
spection, but which manifest themselves by the actions
which result from them, and which do not arise from the
influence of the blood. Such effects may, as we have
formerly proved, be produced by temperature, by light, elec-
tricity, and a number of other influences by contact, to say
nothing of moral causes. It is this which I have had in view
in speaking of the special action of the air on the system,
and which I have designated vivifying influence.
It is thus that the impression of the air serves to
reanimate a life almost extinguished in the case of appa-
rent death, and here man has an advantage over all
warm-blooded animals, even the hybernating, Their skin,
covered with hair or feathers, is less accessible to the
air ; and I have never seen an adult individual which, after
the cessation of all external motion by submersion in water,
has been recalled to life by exposure to the air. Man, on
the contrary, whose skin is bare, delicate, and sensible,
may be re-animated by the action of the air, when he ap-
pears to have lost, under water, sense and motion.
We have shown elsewhere, that new-born children,
when deprived of air, would not give signs of life during
so long a space of time as young mammalia of the same
age, which are born with closed eyes ; they will, however
AIR FROM RESPIRATION. 283
more easily recover from apparent death, because their skin
is adapted to receive a stronger impression from the air.
We have have seen how fatal heat is in cases of asphyxia,
and of very confined respiration. Now, when the action of
the air is reduced to the effects which it produces upon con-
tact with the skin, its influence is the weakest possible, and
at first it cannot easily be conceived what advantage can be
derived from the application of heat. If that application be
of long duration it will be fatal ; in some cases it may be
useful, if it is of short duration. When an animal is plunged
in water, at the temperature of 40° cent, or 104°Fahr., its
motions, are much more forcible, but less numerous than at
inferior temperatures. There are circumstances, then, in
which heat may be momentarily applied in order to excite
the movements of the chest. The immersion of a great
part of the body in warm water, is frequently an efficacious
means of re-animating a child just born without signs of
life. As soon as motion is produced, or if it be slow in
manifesting itself, it will be right to abandon a method, the
prolonged use of which, would be fatal.
We must, therefore, look upon the vivifying influence of
the air in two points of view, its direct action on the nervous
system by contact ; and its action on the blood by the
changes which it produces in it. In like manner, the
vitality of individuals may be modified by a number of
other causes which act immediately, either on the nervous
system, or on the blood. Many facts mentioned in this
work, are examples of both modes of action.
APPENDIX.
ON ELECTRICITY.
In relation to the animal economy, the phsenomena of electri-
city may be divided into two classes : one comprehending the
actions of the external fluid upon the body of the animal,
and the other the electrical influences which he exercises
upon himself.
We shall examine, in the first place, the effects produced
by tension, or the state of a body when charged with elec-
tricity. If a man, or other animal, be placed upon an insu-
lated stool, and put in communication with a body charged
with free electricity : from the moment of contact he will
give the signs which answer the presence of that species of
electricity.
We shall now proceed to the effects which result from
the passage of a single species of electricity through a con-
ductor interposed between the source which furnishes the
fluid, and the common reservoir in which it is going to lose
itself. The molecules of which it is composed will tend to
separate, on account of the repulsive action which they
acquire while charging themselves with a similar electricity.
Were this influence to become sufficiently powerful to over-
286 APPENDIX.
come the force of aggregation which holds the molecules
together, the body would be reduced to powder.
This property may be applied without difficulty to phy-
siological phsenomena, and explains them in a manner
which leaves little to be desired. If an electric spark be
passed through a small drop of blood, the particles which
it contains, will be seen instantly to assume the appearance
of raspberries, which indicates the partial separation of the
elementary globules of which they are formed. If the same
experiment be tried upon a liquid containing spermatic or
infusory animals, a similar effect will be observed, and
these various beings will instantly lose the spontaneous
motion with which they were endowed. In all these cases,
the disorganization seems to consist merely in the forced
separation of the organic globules of which the tissue is
composed. But if the same trial be made upon bodies com-
posed of various heterogeneous tissues, it is manifest, that
the strongest action will be received by the portions best
adapted for transmitting the electric fluid. In a vertebrated
animal, it will therefore be the nervous tissue which will
suffer the most from the effects of an electric shock, and
if its intensity be such, that if the globules which compose
the nervous fibres shall be disjoined, all the functions of
that system will be instantly destroyed, and life will be
irrecoverably lost. Such is the effect of a stroke of light-
ning, and such are the general symptoms which manifest
themselves in man, and other animals, which have been
struck in this manner. No experiments have, indeed, as
yet been made calculated to show the nature of the disor-
ganization undergone by the brain and its dependencies on
such occasions, but it is very well known, that muscular
irritability diappears at the very moment at which life is
destroyed by an electric shock, while it is preserved long
after death from other causes. It is also observed in ani-
APPENDIX. 287
mals struck by lightning, that their blood does not coagu-
late, as in most other cases after death, but remains fluid,
or at least presents only a few inconsiderable clots.
There is another kind of influence which deserves still
more attention, since it appears, that it is to it that the re-
action, which the body of an animal is capable of exerting
on itself, are to be referred.
In 1789, Galvani observed by chance, that a metallic
circle, composed of two heterogeneous metals, placed in
contact on one hand with the muscles, and on the other
with the nerves, instantaneously produces contractions of
the muscular structure comprehended in this circuit. The
physical explanation of this fact was furnished by Volta,
who demonstrated, that two conductors in contact, become
charged with opposite electricities, and that when they are
united by a third body, capable of transmitting the electric
fluid, a current is established within, owing to the neutra-
lization of the fluid collected in the metals. It is this cur-
rent which determines muscular convulsion, when the nerve
of a muscle serves as a conductor, and sensation, when one
of the cerebral nerves is employed, as in the experiments of
Galvani and in others, equally remarkable, which are related
in the more ancient work of Sultzer, entitled Theorie du
Plaisir.
Let us more clearly examine each of these properties, and
we shall see to what order of phenomena, we are now enabled
to refer them.
It is well known to physiologists, that the integrity of
the division of a nerve which supplies a muscle, and the
free circulation of the blood through the vessels which are
distributed to it, must be considered as the necessary con-
ditions of the contractile power.
Anatomists are aware that the muscles present con-
siderable analogy in all the animals in which they can be
288 APPENDIX.
observed with sufficient plainness. They are bundles of
fibres, soft, flexible, yielding, and of very various lengths.
A cellular tissue of great delicacy unites them together,
and their extremities lose themselves in the common mass,
or attach themselves to tendons, which form the medium of
connection between the muscle and the parts which it is
designed to move. The manner in which their fibres are
grouped is very various, but the muscular tissue appears
to be strictly the same in all cases. Its colour is white, and
if in warm-blooded animals it appears red, this must be at-
tributed to the fluid which bathes it. We shall subdivide
the muscular fibre into three orders. We shall call tertiary
fibres, those muscular filaments which are found on cutting
the muscle longitudinally : we shall call secondary, those ob-
tained by the subdivision of the former : they are very well
marked, inasmuch, as it is impossible to subject them to any
mechanical alteration without arriving at the primary fibre,
which the labors of Home, those of Henry Edwards, and
our own, have made known in a very satisfactory manner.
Henry Edwards found the elementary fibre the same in all
animals and at all ages, and formed, in all cases, of a series
of globules of the same diameter. From the combination
of a bundle of primary fibres, result the secondary fibres,
upon which our attention must be fixed, inasmuch, as
the contractile movements are effected by their means.
When they are examined with a magnifying power of
300 diameters, they exhibit themselves frequently in a very
peculiar manner, which might lead into error respecting
their real composition. They are seen like cylinders,
crossed by a considerable number of little sinuous lines
placed at the regular distance of the 300th part of a mil-
limetre. This appearance seems owing to the membranous
sheath in which they are invested, and is not found in
secondary fibres which have been cut or torn. It disappears
APPENDIX. 289
likewise in certain states of illumination, when the true
muscular structure becomes manifest, and appears com-
posed of a considerable number of small elementary threads
placed parallel or nearly so.
If a muscle be taken sufficiently thin to be examined as
a trans parent object, without its being necessary to divide
it, it will be seen that it results from the combination of a
certain number of secondary fibres placed sometimes with
little order, one beside another, parallel, or nearly so, and
often grouped so as to produce the muscular bundles which
are conspicuous in thick muscles. These are held together
by an adipose cellular tissue, and are traversed in various
directions by vessels and nerves which seem to pervade the
muscle, without having any easily observable connexions
with it. We cannot now enter into the history of the cir-
culation peculiar to these organs, and shall therefore only
observe, that if there exists a material communication be-
tween the muscular fibres and the bloodvessels, it can only
be conceived on the supposition of transudation taking place
through the coats of the vessels. The passage from the
arteries to the veins is easily traced, and does not pre-
sent the extreme division which would be indispensable
to the nutrition of the organ, if it took place as it is generally
imagined.
Let us now examine these muscular bundles, independ-
ently of the accessory organs, and with a very weak magni-
fying power, to obviate all objections to which the use of the
microscope is liable. If the muscle be at rest, we merely
see a number of straight parallel fibres, which are very
flexible and so disposed as easily to change their position
with the least motion of the muscle.
When this appearance has become familiar to the eye,
we can appreciate the changes which are effected at the
moment of contraction. For this purpose, we take a muscle
u
290 APPENDIX.
recent and thin, the sterno-pubic muscle of the frog, for
example. We place it under the microscope, and submit
it to galvanic influence by means of a very simple arrange-
ment, described in our Essay upon Spermatic AnLmalcula.
As soon as the current is established, the muscle contracts
and presents a most remarkable appearance. The parallel
fibres which compost it are suddenly bent zigzag, and present
a great number of regular undulations. If the current be
interrupted, the organ resumes its original appearance, and
bends again when it is re-established. It is even easy, when
the muscle is strong and irritable, to repeat the experiment
a number of times. In general, however, the muscle must
be renewed after two or three trials.
The precision and instantaneousness of these changes
render this phenomenon one of the most curious in physi-
ology. On examining it with attention it will be perceived,
that the flexions take place at determinate points, and do
not change their position, which seems to indicate, that it
is occasioned by the momentary attraction of these points
to each other.
In all the muscles the same peculiarity is discovered.
Warm as well as cold-blooded animals exhibit, it; and birds
as well as mammifera. It is also perceived without diffi-
culty in the muscles of the stomach, the intestines, the
heart, the bladder, the uterus, &.c.
On the surface of the secondary fibres, and in the inner
part of the angle which they form, when contracted, may
be remarked wrinkles or folds, owing evidently to the forced
bending to which they have been subjected. This appear-
ance is frequently very well marked ; in other cases it is,
less so. This arises only from the energy of the contraction.
When it is weak, the angle is obtuse, and the fibre does
not undergo sufficient flexion to occasion these wrinkles ;
but if it becomes more acute, the inner part of the bundle
APPENDIX. 291
must necessarily be compressed, and thus form wrinkles.
It is even probable, that this cause limits the energy of the
contractions, and prevents them from passing a certain
angle. At least, it is certain, that in the muscles of loco-
motion, we have never been able to produce contractions oc-
casioning angles so acute as 50°. The fibres of the intestinal
muscles, however, frequently exhibit themselves at angles
even more acute. But, in the first place, the summits of the
angles are sensibly more distant th an in the other muscles, and
in the next, their secondary fibres are thinner, and are dis-
played over alarger surface. It will readily be conceived, there-
fore, that they are in a situation altogether peculiar, and that
each fibre contracts, as it were, independently of the others,
and without being constrained by the surrounding bundles.
Having observed the phenomena just described, it was
essential to determine all their conditions. It was possible,
that the muscular fibre might have undergone other changes
besides those which we had perceived, and that, on this
supposition, it might undergo a variation in bulk. Ancient
anatomists, and among them Borelli, had believed, that the
bulk of the muscle was sensibly augmented at the moment
of contraction. This opinion, which was not founded upon
any measurement, was overturned by Glisson. He caused
the arm of a man in the state of rest to be immersed in a
bucket filled with water, and he thought he perceived a lower-
ing of the surface as soon as the muscles came into play.
This experiment was repeated with more care by Carlisle,
who uniformly arrived at the contrary result. More judi-
cious observers have, however, perceived, that these ex-
periments were deceptive, since no allowance was made for
the alterations in the skin, and sub-cutaneous cellular
tissue, when compressed by the muscular effort. Blane
pursued a method similar to that of Carlisle ; but he took
the precaution to make use of a compact muscular mass^
v2
292 APPENDIX.
and placed in the vessel a piece of an eel, which he stimu-
lated by means of a pointed metallic wire. This method
having shewn him no alteration in the level of the liquid,
he inferred from it, the equality of volume in the two states
of the muscles. But before him, and without his know-
ledge, Barzoletti, by a much more elegant experiment, had
arrived at precisely the same conclusion. He suspended in
a bottle, the posterior part of a frog, filled the bottle with
water, and closed it with a cork, through which was passed
a narrow graduated tube. He then found the muscle to
contract by the stimulus of galvanism, and in no case
could he observe, the least variation in the column which
the tube contained.
The apparatus which we employed did not differ, in its
principal conditions, from that of Barzoletti ; though we
made use of larger masses of muscle, and not having per-
ceived any disturbance of the level, we also came to the
same conclusion as Blanc and Barzoletti.
The experiments just related were sufficient to show, that
the muscle underwent no alteration, except in the direction
of its fibres. Great importance being thus given to the
examination of the sinuosities which the muscular fibres
describe, we were induced to devote some attention to this
subject.
l q r t
h k p s u
APPENDIX. 293
On one of the muscles of the leg of a frog being placed
under the microscope, and made to contract by means of the
pile, we held over it, in several places, the broken lines as
above, and carefully compared them with the natural sinuo-
sities, making use of both eyes. We afterwards completed
the triangles by means of the dotted lines and took the fol-
lowing measures.
Length of the lines. Distance of the points.
ao — 10mm. ab — 17mm.
ob — 10 cd — 16
en — 10 ef — 16
nd — 10 gq — 42
em — 10 ry — 39
mf — 11 Total 130
gh - 10
hi — 10
ik — 11
kl — 11
lp — 12
st — 11
tu — 12
uv — 12
vx — 10-5
xy- 12
Total 172-5
If we suppose the 16 lines in the above table to form a
series, we shall have 172'5 for the distance of the points,
a and y, when the fibre is straight, and only 130, when it is
contracted. This indicates, a shortening of 0*23 in the
fibre.
294 APPENDIX.
But it was possible to assure ourselves directly of the
truth of this fact, by taking the same muscle and measur-
ing it with care, in the two states of relaxation and con-
traction. For this purpose, as soon as we had taken the
muscle from the body of the animal, we placed it under the
microscope, to ascertain that its fibres were quite straight,
and then measured its length by means of a pair of com-
passes. We afterwards stimulated it to contraction by the
current of a weak pile, and took a new measure whilst it
was in that state.
Relaxed muscle 25mm.
Contracted 17mm
20
15
25
18
20
15
90 65
By this method the diminution was found to be 0*23 .
We may then conclude, that the flexion of the fibre repre-
sents in reality the quantity by which it is shortened, which
proves, that the change which it has undergone, is refera-
ble to direction only.
This consideration is so much the more important, as
many facts commonly known prove to us the elasticity of
muscular fibre, and there might be some reason for sup-
posing, that that property was concerned in the phenome-
non of contraction. We shall now detail what we know
with precision on the subject. Living muscle, abandoned
to itself, always assumes the regular state in which we sub-
jected it to examination ; but, when its two extremities are
fixed, and the distance of the points of attachment is in-
creased, the fibre lengthens in virtue of its elasticity, as
APPENDIX. 295
shewn by old experimenters, who have endeavoured to es-
timate the weight necessary to produce its rupture. It
is evident, that this action is of an opposite nature to that
which produces contraction, and which it ought to resist
in its effects ; at least, we are authorized to think so after
the following experiments. We took female frogs a short
time before spawning. Their abdomen was very much
distended by the eggs, and the sterno-pubic muscles must
have yielded to the increase of bulk and become lengthened.
We separated these muscles from the cellular tissue, and
from the other parts of the abdominal parietes. We de-
termined their lengths, and then we cut one of their ex-
tremities. At that very instant they underwent a remark-
able shortening; but on examining them with the micro-
scope, we ascertained that that phenomenon was not accom-
panied by any flexion of the fibre, and that it consequently
differed from its ordinary contraction. Being afterwards
subjected to galvanic influence, the same muscles further
diminished in length, presenting the usual sinuosities. We
shall here give the numerical proportions, which express
the conditions of these two phenomena.
Muscle in its place 45mm. Cut 34mm. Contracted 22mm.
49 36 25
51 37 27
145 107 74
These numbers are nearly in the proportion of 30 — 20 — 15;
in other words, a muscle, whose strong contractions are equal
to a quarter of its length only, may be brought, by means of
continued traction to the distension expressed by the pro-
portion 2 : 3, without undergoing any alteration in its con-
tractile power.
296
APPENDIX.
When we reason upon this fact, a view is presented to
the mind, which altogether destroys the objection which
might be drawn from certain cases of extraordinary con-
tractions, apparently difficult to be reconciled with our
theory. In fact, the stomach, the intestines, and the
bladder, exhibit to us variations of volume, which are almost
incredible; and, although, their muscular structure is such,
that it is easy to explain why their contractile power pro-
duces results much more powerful than those, the intensity
of which we have measured in the mucles of locomotion, it
is no less true, that they would be much less than they are,
if the elasticity of their fibres did not act an important part
in that phenomenon. The explanation of the facts becomes
very easy if we make use of the two following principles :
1. The muscles are elastic, and consequently capable of
being lengthened under the influence of traction exerted at
their point of attachment; 2. Their contractile power may
act in all cases ; but it probably increases in force as it ap-
proaches to the natural state of the muscle. It results from
these two properties, that the stomach and intestine, for
example, may be greatly distended by the pressure of ali-
mentary matters. If in such circumstances, any stimulus
is made to act upon them, they will undergo successive
contractions, which will gradually follow the foreign bodies
included in their cavity, until atlength they attain their point
of rest. Their muscular fibres were straight while they were
distended, they are so still in this latter state. This power
of extension is much facilitated by the secondary fibres of
these muscles being very thin and very long. They are dis-
posed nearly on the same plan, and are united by means of
a very loose cellular tissue. These various circumstances
permit them to be easily separated ; they do so in fact when
the organ is stretched, and if this trial is carried too far,
APPENDIX. 297
rupture takes place, and that in the intervals between the
muscular fibres.
The contraction of these organs differs then entirely from
that of the muscles of locomotion. The latter are fixed in
an invariable manner at their extremities, and can scarcely
undergo more than a single contraction, or, if they undergo
a certain number, they are alternate, and always bring back
the organ to the same point. In the abdominal viscera, on
the contrary, it is by means of a series of contractions that
the muscles gain the point of rest.
Let us now examine the connexions which exist between
the phenomena just adverted to and the nervous system.
It is well known that a muscle contracts, 1. When its
nerve communicates freely with the brain, and there exists
in that organ the will to produce a contraction; 2. When
the nerve is pinched, after its connexions with the brain
have been destroyed ; 3. When the current from a galvanic
pile is passed through it ; 4. When it is touched with
active chemical stimuli, such as concentrated mineral acids,
chlorurets of antimony, bismuth, &c.'; 5. When placed in
contact with a hot body. Since it is evident that the pre-
sence of the brain is not necessary to the exercise of the
contractile power, we shall at once set it aside, and pass on
to the examination of the contractions determined by means
of the pile.
If one of the poles of a galvanic pile be placed in contact
with the nerve, and the other in communication with the
muscle, the latter undergoes contractions.- In order that
we may form a distinct idea of the course of the galvanic
fluid in this experiment, it is necessary to study more closely
the relations which exist between these two organs.
The nerves present to the naked eye, a satin-like appear-
ance, which was first particularly described by Fontana.
298
APPENDIX.
It is particularly sensible in the nerves of the cat, the rab-
bit, the guinea-pig, and the frog. When they are examined
with a power magnifying from 10 to 15 diameters only,
alternate lines of light and dark are seen, which forcibly
suggest the idea of a spiral coil situated beneath the neur-
elema. After a series of varied experiments, we were con-
vinced that this appearance, like that of the tendinous
tissues, was owing to a little pleating of the fibres of the
neurelema, which loses its transparency in some parts, and
preserves it in others. This would merit little attention,
did it not present a very certain criterion for recognizing
the little nervous threads, and render them easily distin-
guishable from the blood-vessels or lymphatics. If the
neurelema of a nerve be divided, and the nerve be then
spread out under water, it is seen to be composed of a great
number of very small parallel fibres, which appear to be
continuous throughout the length of the nerve ; at least,
they are no where seen to divide or unite. Their filaments
are flat, and composed of pure elementary fibres, placed
nearly on the same plane, which gives them the appearance
of ribbons. These fibres are formed of globules, and pre-
sent a remarkable circumstance, namely, that the two
outer are the most distinct. The middle series can be seen
only occasionally, doubtless because the pressure which they
undergo effaces the line of demarcation of the globules com-
posing them. The number of these secondary nervous fibres
is very considerable as the following calculation will shew,
although the data of the observation may not be admitted as
rigorously correct. Let us suppose, that each elementary
nervous fibre occupies in the section of the nerve, ■jfa of a
square millimeter, we shall have 90,000 for every square
millimeter. But we know that the secondary fibres include
four elementary fibres, there must then be 22,500 in the same
APPENDIX. 299
space, or about i 6,000 for a cylindrical nerve of a millimeter
in diameter, such as the crural nerve of a frog, for example.
If a nerve be examined at its entrance into a muscle,
and followed attentively, it will be seen to ramify in a man-
ner which at first appears not to be very regular, except that
there is a tendency in the branches to direct themselves
perpendicularly to the muscular fibres. This observation
may be easily made upon all muscles, such as those of the
ox, cat, &c. ; but it requires in this case precautions regard-
ing light, which render it painful and fatiguing. It is on
the contrary, very easy to discern it in the thin muscles of
the frog, on account of their transparency. After having
thus followed one of the nervous branches as far as ob-
servation with the naked eye and the lens will permit, it be-
comes easy to fix the point at which we mus stop, and to
continue the examination assisted by higher magnifying
powers. As the nerve arrives at its ultimate ramifications,
it widens, and its secondary fibres separate and display
themselves, precisely as when it has been stripped of its
neurelema. This little nervous trunk then presents the
appearance of a fibrous cloth, from which some threads are
occasionally seen to shoot into the muscle, perpendicularly
to its own fibres. Sometimes there are two nervous trunks,
parallel to the fibres of the muscle, which proceed at some
distance from one another, and mutually send across little
threads, which are seen to pass through the muscular space
which separates them, cutting it at right angles. Some-
times the nervous trunk is itself pressed close to the fibres
of the muscle, and the threads which it furnishes spread
out, preserving this direction, run through the organ, and
return on themselves, forming a loop. But in all cases, it
is observed, 1st, that the extreme nervous ramifications are
parallel to each other, and perpendicular to the fibres of the
300 APPENDIX.
muscles ; and 2ndly, that they return into the trunk which
has furnished them, or anastomose with a neighbouring
trunk. But, in all cases, it appears very certain that they
have no termination, and that their relations are the same
as those of the blood-vessels. Now, let a galvanic stream
be passed through a muscle examined in this manner, and
it will be seen, that the summits of the angles precisely
correspond to the passage of these nervous filaments. Be-
fore admitting this fact, we subjected it to all the verifica-
tions that we could think of, and it was only after having
repeated and varied our experiments in every possible way,
that we considered ourselves warranted to adopt it. All
preparations do not succeed, but in the delicate muscles of
the lower jaw of the frog were found the best specimens
that could be discovered.
It becomes then very probable, that the nerves approach,
and thus determine the phaenomenon of contraction. Now,
what is the cause which forces them to advance towards
each other? It is impossible here not to recognize the ap-
plication of the beautiful law discovered by M. Ampere.
It remains to investigate how far it is applicable. If
two streams attract each other, when they go in the same
direction, it will be enough to suppose, that the nerve
transmits the galvanic fluid more easily, and in more con-
siderable quantity than the muscular stratum itself, (which
is quite in accordance with experiment,) in order to form a
clear idea of the phsenomenon in question. Indeed, if we
interpose a muscle between the poles of a pile, it will be
found to be traversed by the fluid, but in an unequal man-
ner, on account of the better conducting power of the nerve.
The branches of this being parallel, will reciprocally attract
each other, and will thus determine the flexion of the fibre,
and the shortening of the muscle.
Admitting the correctness of this opinion, it will easily
APPENDIX. 301
be conceived, that the living muscle is really a galvanometer,
and the short distance between the conducting branches on
the one hand, and their tenuity on the other, unite in giving
it an extraordinary sensibility. We shall now consider it
in this point of view, and compare the phsenomena of mus-
cular contraction with the experiments on the moving power
of electricity, with which natural philosophy has of late
years been enriched.
The beautiful experiments of the Italian philosophers
upon muscular contraction, produced by the contact of
heterogeneous matters, are generally known, and we have
now increasingly strong grounds for believing, that these
motions are owing to the passage of a small galvanic stream.
But admist all these results, it will be remarked, as
Humboldt has clearly shewn, that the contractions manifest
themselves at the moment when the communication between
the nerve and the muscle is etablished, by means of a single
metal. This is generally explained, by supposing that the
metal and the muscle become placed in opposite states of
electricity, and that the neutralization of the two fluids is
effected through the nerve.
If to each end of Schweigger's galvanometer be fitted
similar plates of platina, and if around one of them be fixed
some ounces of muscle, recently taken from a living animal,
and if they are then plunged into blood or water, slightly
impregnated with salt, the magnetic needle will deviate, and
the stream will go from the metal to the muscle.
It appears then, that the view which has been adopted
is accordant with experiment, and we might regard this
method as an excellent means of comparison between
Shweigger's galvanometer and the frog. In fact, if we
arm the muscle and nerves of the animal with portions of
the wire, which forms the galvanometer, and then bring
302
ATPEND1X.
the two ends of the apparatus in contact with the armatures,
the contractions will be strong and frequent. The needle,
however, in the majority of cases, will not change its posi-
tion ; and if, sometimes, slight oscillations are thought to
be perceptible, they only serve still further to prove the
want of sensibility of the instrument.
The animal, with exquisite sensibility, indicates all the
electric currents which influence the galvanometer, as for
example, the action of an incandescent metal upon a cold
one, that of an alkali upon an acid, and that of two oxidable
wires, unequally immersed in an acid. It is very certain,
however, that if we did not possess the galvanometer, it
would be impossible to present an exact analysis of these
various phenomena, since the frog does not indicate the
the direction of the current.
We easily perceive, in all that has been adduced, the
power of the electric fluid in producing muscular contrac-
tions, and we know, from other experiments, that it is
indispensable, that that fluid should be in motion. If a
frog, prepared and insulated, be brought near the charged
plate of an electrophorus, the nerves, like all other light
bodies, will be strongly attracted. The frog will give very
marked signs of free electricity ; but the attractions will
manifest themselves, only at the moment when the spark is
taken. Thus, every time that the galvanic current passes
through a living muscle, the contractions of that organ
betray its passage. We have now to show, that in all cases,
where contractions are produced, there also exists a develop-
ment of electricity.
For this purpose, let two similar platina wires be fitted
to the ends of the branches of the galvanometer ; let one of
them be plunged in the muscles of the frog, and the nerves
of the animal be touched with the other, heated to redness.
APPENDIX. 303
The contractions will be strong, and the deviation of the
needle very sensible. Both these phenomena will be pro-
duced, but with less intensity, if the heated metal be ap-
plied to the muscles.
Let a platina cup, filled with nitric acid, be now substi-
tuted for one of the wires, and fix to the other a fragment
of nerve, muscle, or brain ; at each contact the needle will
deviate, and the stream will proceed from the acid to the
animal matter. Similar effects may be obtained with chlo-
ruret of antimony.
With regard to pressure or pricking, which are only modi-
fications of the same thing, we have not been able, in this
kind of experiments, to detect the electricity which they
must excite; but the beautiful discoveries of Becquerel
leave no room for doubt on this point; and the difficulties
which we have experienced depend on circumstances which
render modifications in the apparatus necessary.
Besides, we ascertained, by experiment, that by the
slightest pressure, two living animal substances acquire
opposite states of electricity. It is sufficient for two insu-
lated persons to touch hands, and then withdraw from the
contact, to develop an excess of electricity sufficient to
affect the electroscope of Caulomb.
It is proper to remark, that the greater part of these
effects are not connected with the existence of life, but it
is very evident, that when death has affected the organs
which are submitted to this kind of action, the conducting
power of the nerves may have been essentially modified. It
is even possible, that that may be the only circumstance
which determines the irritability of the muscles, without
which, it would not always produce the approximation of
their nervous branches. The arrangement of the tissues is
so delicate, that when matter abandoned to itself is with-
drawn from the power which had organized it, it must, in a
304 APPENDIX.
short time, lose the properties with which it had been en-
dowed.
It may be supposed, that this hypothesis is not appli-
cable to all the circumstances of contraction ; but the results
recorded in our memoir, and which may be obtained with
great facility, readily shew that it is.
The insulation of the nervous fibres, is produced by the
abundant fatty matter, for the discovery of which, we are
indebted to Vauquelin. It surrounds each of the fibres,
and does not permit the electric fluid to pass from one to
the other.
Besides this arrangement, which exists in the interior of
the nerve, under the neurelema, there is always, round the
nervous trunk itself, and external to its covering, another
bed of fat, which exhibits itself in its most minute ramifi-
cations. It will be obvious, that by means of these pro-
visions, the electric fluid, which has arrived in the nerve,
cannot deviate to take a different route.
Hitherto we have rather regarded the effects resulting
from an extraneous action upon the animal economy. It
now remains to shew, that there are internal phenomena,
the result of the reaction of one organ upon the neighbour-
ing organs, which may also receive some light from known
physical facts.
The fluid with which the sanguineous system is filled,
contains pure caustic soda, in sufficient quantity to impart
to it manifest alkaline properties. Now, the greater part
of the materials separated from the blood by the secreting
organs, differ from it entirely in this respect. Some, as
the bile and the saliva, are alkaline also ; but they contain,
in proportion to the quantity of animal matter, a much
larger quantity of soda than is found in the blood. Others,
as milk, and chyme, are, on the contrary, acid, and owe
this property to the presence of the lactic, phosphoric,
APPENDIX. 305
and other acids, which are also met with in the blood, but are
naturalized by alkaline bases. Lastly, the urine and sweat,
in the state of health, present themselves under two different
conditions. They are generally acid, but sometimes neutral.
What is called sweat, in the ordinary acceptation of the
word, is always acid; but the liquid, which is continually
evaporating from the skin, as well as the water which ac-
companies the air as it issues from the lungs, is found, when
collected, to be neither acid nor alkaline, and their analysis
shews only a small proportion of animal matter, accom-
panied by some traces of alkaline hydrochlorates. The
urine is always acid in health ; but this character is scarcely
apparent, if the individual has drunk a large quantity of
water some hours before.
If we seek among the facts known in chemistry, for an
explanation of this difference between the constitution of
the blood, and that of the fluids secreted from it, we may
soon be convinced, that the action of the voltaic pile, is the
only one which approaches to it. Moreover, it appears pos-
sible, artificially to imitate the principal conditions of the
secretions, and to separate from the blood, by means of
the pile, a liquid resembling milk, and from the food itself,
a material resembling chyme.
We recommend this subject to the attention of medical
men, inasmuch as they may find in it some valuable hints
respecting the use of various medicines. Many of these
act too evidently on the secretory functions, and too plainly
disturb their equilibrium, for us not to ascribe their action
in a great degree to this peculiar effect. We need merely
mention, mercury for the bile and saliva, and diuretics for
the urinary functions.
We cannot conclude this chapter without remarking,
that if muscular motion and the secretions may be re-
garded as owing to electrical movements, the production of
x
306 APPENDIX.
animal heat can only be suitably explained in the same
manner; for it is known to electricians, that the conducting
wire acquires considerable heat during the action of the
pile. M. de la Rive, the learned Professor of Chemistry at
Geneva, was the first to seize the happy idea of referring the
phenomena of animal heat to electric agency.
307
ON MUSCULAR CONTRACTIONS PRODUCED BY BRINGING
A SOLID BODY INTO CONTACT WITH A NERVE WITHOUT
A GALVANIC CIRCUIT. BY DR. EDWARDS. Read before the
Royal Academy of Sciences, MAY, 1825.
The experiments of galvanic or muscular contraction ex-
cited an interest in the scientific world, which gave rise to
many important researches. It seemed that a new epoch
in physiology had commenced. This was really the case,
not merely as regards the singular character of the newly
discovered phenomena, but with respect to the fundamental
results to which they led. The creation of a new branch
of natural philosophy, was another and not less remarkable
consequence.
Physiologists, who at first had hoped for too much, were
too soon discouraged. From the close of the last century,
when Humboldt's celebrated work on Galvanism made its
appearance, up to a very recent period, but little attention
was directed to researches of this kind. It was natural that
attention should again be excited by the new impulse given
to this branch of science by Professor CErsted, nor could the
researches of Becquerel, which have so greatly increased
our knowledge of this subject, fail to revive the hope, that
electricity might be satisfactorily called in to explain some
of the phenomena exhibited by animal life. Accordingly,
Prevost and Dumas shortly after, laid before the Academy
of Sciences, a memoir, which called forth a very lively in-
terest. They described the terminations of nerves, and ex-
hibited their relation to the muscular fibre, in a manner
which introduced perfectly new ideas on the subject of
x2
308 APPENDIX.
muscular contraction. Their proofs are grounded on the
evidence of the senses, and the testimony of several of the
members of the Academy confirms the accuracy of their
observations. (Their views are given in the preceding
Appendix, to which it is sufficient to refer, more particu-
larly to page 302, el seq., where they endeavour to shew,
that in all cases in which muscular contractions are in-
duced by external excitation, there also exists a develop-
ment of electricity.) This fact, is very much in favour of
the opinions advanced by these physiologists, that the mus-
cular contractions thus excited, depend upon the electricity
developed by the action of these stimuli. There is, indeed,
the simultaneous production of electricity, and of muscular
contraction, but the question may be asked — is it by virtue
of this production of electricity, that the contractions take
place ?
Though it is well known that electricity, provided it be
in sufficient quantity and applied in a particular manner,
gives rise to muscular contractions, we do not know whether
the fluid, disengaged by the three modes of excitation al-
luded to, is in the conditions necessary to produce such
contractions.
Being occupied with some researches on the nervous sys-
tem, I had occasion to examine a mode of mechanical
excitation, which appeared to have been previously neg-
lected, and which led me to some observations which bear
on the question above stated.
The procedure consists in passing a solid body along a
nerve, in the same manner in which we pass a magnet along
a bar of steel which we wish to magnetize. In doing so,
the object is not to act by pressure, although, more or less
must be exercised in every form of contact, but rather to
touch various contiguous portions successively, and we have
it always in our power to bear as lightly as we please.
APPENDIX. 309
In order to pass the exciter along a certain portion of
nerve, it is necessary that the nerve should be supported
and kept more or less tense. These conditions are fulfilled
when a portion of nerve is simply laid bare, while its con-
nexions, superiorly with the rest of the nervous system,
and inferiorly with the muscles to which it is directed, are
left unimpaired.
Expose the entire sacral portion of the sciatic nerves of a
frog, by removing the skin and muscle which cover them.
Take off the skin from the lower limbs, in order to see the
contractions of the muscles, and pass under the nerve a
slip of oiled silk to bring them better into view, and also to
make them even with the sacrum.
We have then by this preliminary step, an animal, whose
sciatic nerve can be both better seen and touched, and in
whose lower extremities, the slightest muscular contraction
cannot take place without being visible. In order to cut
off voluntary movements, which would interfere with and
derange the experiment, the spinal marrow should be di-
vided immediately below the head.
Having the animal thus prepared, touch the sciatic nerve
in the before-mentioned manner, with a slender rod of silver.
The muscles of the corresponding limb will be thrown into
contractions, and such will continue to be the result when-
ever this treatment is repeated, however delicate the con-
tact.
The exciter is to be drawn along the whole extent of the
denuded nerve, which will be from a quarter to a third of
an inch in length. Contractions are also produced by rods
of various other metals, such as copper, zinc, lead, iron,
gold, tin, and platina. I took care to employ metals of
the utmost purity, in which state I was supplied with them
by the essayers of the mint. It is not necessary that the
rod should be metallic ; I succeeded with glass or horn.
310 APPENDIX.
To produce muscular contractions, it is sufficient that the
nerve be touched with any solid body in the manner above
related.
This method of producing contractions, by successively
touching contiguous points of a small extent of nerve, em-
ploying only a single body which has no connexion with
the muscles of the leg, appeared to afford a favourable
opportunity for examining the principle of this excitation ;
that is say, of ascertaining whether it causes contractions
through the intervention of an agent altogether unknown to
us, or whether it does so by means of electricity, mechani-
cally excited.
My first researches were directed to discover, whether
any difference of action resulted from the use of different
exciting substances, whilst all the other conditions re-
mained sensibly the same : I plainly saw that iron and zinc
produced far less vigorous contractions than other metals,
but I was unable to establish in a satisfactory manner, the
scale of gradation. I could not even hope to do so, for
variations in the state of the animal, occasioned differences
in the contractions, under the influence of the same exciter,
as great, or perhaps greater, than those which depended on
the nature of the metals employed.
I was satisfied with having ascertained, that these ex-
citers sensibly differed among themselves, and gave up the
idea of a scale, which the subject would hardly admit of>
and which, moreover, would not directly lead to the object
which I had in view.
The question in fact, as before stated, was to determine
whether in the preceding experiments, the muscular con-
tractions were occasioned by an agent altogether unknown
to us, or whether they were effected by electricity, which is
developed every time one body exerts a mechanical action
on another.
APPENDIX. 311
If electricity produced by the contact of the exciter with
the nerve, were really the cause of the contractions, we
might by greatly diminishing the quantity of electricity in
the nerve, either sensibly diminish, or altogether suspend,
muscular contractions. Now, these effects may be pro-
duced by varying the conducting power of the substance
placed under the nerve. Thus, when the nerve maintains
its natural relations, it rests on muscle, which is an excel-
lent conductor of electricity. If, whilst the nerve is so
situated, it be acted upon by a given quantity of electric
fluid, this will be divided between the nerve and the mus-
cle, and thus there will be a diminution of the excitation of
the nerve, and of the intensity of the phenomena resulting
from it. If, on the contrary, we place under the nerve
which we wish to excite, a non-conducting body, the whole
of the electricity will be concentrated upon the nerve, and
we shall obtain from the fluid the full effect which we are
desirous of producing. This precaution is had recourse to
in galvanic experiments, when it is wished to excite muscu-
lar contractions by very small quantities of electricity ;
such for instance, as are produced by the contact of two
metals.
To ascertain the respective influence of the insulation,
and non-insulation of the nerve, the comparison must not
be made without giving attention to the state of the ani-
mal.
If the animal be very fresh and excitable, the contrac-
tions will, in both cases, be so strong that the difference
will not be perceptible : for no conclusions can be drawn
from the comparison, if motion takes place in the limb,
under circumstances the most unfavourable, since we should
then be commencing almost where gradation ceases.
On this account, it is proper to wait till the animal is so
3J2 APPENDIX.
far exhausted, that no muscular contractions, sufficient to
move the limb, can be excited by the action of two metals
on the nerve whilst it is resting on muscle. We may thus
obtain the simple contraction of the muscle without loco-
motion, or even suffer muscular contraction to cease.
If, in this state of things we place a non-conducting
body, as a piece of glass or oiled silk, under the nerve, and
then establish the circuit by means of two different metals,
we immediately cause the agitation of the limb.
This fact, and the principle on which it depends, being
well established, the next step was to ascertain, whether
in the preceding experiments, in which the nerve was
touched with only one body, and no circuit was formed,
the muscular contractions were to be referred to the action
of the same cause. It will be remembered, that a slip of
oiled silk was placed under the portion of denuded nerve.
A comparison was now to be made between an animal so
prepared, and another in which the nerves, instead of being
insulated, reposed on the subjacent flesh. I made use of
small rods, with which I easily excited contractions, when
I drew them from above to below, along the portion of de-
nuded nerve, which was supported by the oiled silk ; but I
was unable to excite them when I passed them along the
nerve of the other animal, in which they were not insu-
lated. Frequent repetitions assured me, that the want of
effect did not depend on difference in the degree of con-
tact ; I tried the experiment on many animals of the same
species, lest there might be anything in individual pecu-
liarity. As in the one case the nerves were brought farther
into view, and kept somewhat tense and even with the
sacrum, by means of the slip of oiled silk, whilst in the
other they had no such support, I restored the parity of
position, by placing under the unsupported nerves, a portion
APPENDIX. 313
of muscle, corresponding to the slip of oiled silk, as well in
size as mode of insertion, and still was unable to produce
contractions by treating the uninsulated nerve, whatever
was the material of the rod employed as the exciter. The
difference was rendered still more striking, when instead of
making the comparison between two individuals, it was
made upon the same animal. After having in vain at-
tempted to produce contractions by contact of a nerve rest-
ing upon muscle, I found that they might still be induced,
•if the oiled silk were had recourse to, and I was able to
command their alternate appearance and disappearance,
by using sometimes a non-conductor, and at others, a con-
ductor for the support of the nerve.
The manipulations which cannot be avoided, in making
these trials, exhaust the nerve if they are too often re-
peated.
The difference is here as marked as possible. So decided
a contrast as this was not necessary ; a less, would have
sufficed, provided it were really manifest. The reason is
not obvious, why contractions should not sometimes be
produced when the nerve is not insulated, since in galvanic
experiments, the quantity of electricity, elicited by the con-
tact of two metals, will or will not produce contractions,
according to the state of vitality of the animal, which not
merely differs in different individuals, but varies in the
same individual at different moments. This extreme of
contrast in the effects, at first very satisfactory, as more
strongly exhibiting the influence of the respective states,
and throwing light on the nature of the cause, seemed, on
a closer view, to prove too much, by uniformly exhibiting
the same difference.
I wished to be able sometimes to produce contractions by
touching the uninsulated nerve, as happens in ordinary
314 APPENDIX.
galvanic experiments, in which the contact of two metals
is employed, though they might be expected to be less
marked than in the latter case, since my method of excita-
tion was one of inferior energy. I at length succeeded in
this point. In observing the difference of effect in touch-
ing an insulated nerve, more or less rapidly, T discovered
that contractions were the most constantly produced by a
quick and light touch.
Having found that I produced contractions more easily by
increasing the rapidity of the taction, I made trial on an
animal whose nerve was not insulated, and frequently ob-
tained slight contractions.
In the preceding experiments, choice has been made of
the extremes from amongst the good and the bad conductors,
suitable to be placed under the nerves, for it is necessary
that they should lie on a soft material, in order not to be
irritated, and compressed between two hard bodies. Thus,
the slip of muscle, and the piece of oiled silk, are both soft
and flexible, but the one is the best conductor, and the
other the best calculated to insulate ; they, therefore, offer
the most favourable conditions for obtaining distinctly,
marked, but opposite results. Notwithstanding the diffi-
culty of obtaining appreciable differences, when employing
substances of intermediate properties, I did not restrict
myself to the two before-mentioned. Having prepared a
frog, in the manner already described, I placed under the
sciatic nerves, a piece of the skin of the animal, and under
those of another, I introduced a slip of moistened paper,
and perceived a marked difference j when, in the same
manner, and with moderate quickness, I alternately touch-
ed the nerves, first of the one, and then of the other. The
frog, whose sciatic nerves were supported by the piece of
skin, remained motionless, whilst the same degree of tac-
APPENDIX. 315
tion applied to the nerve, resting on moistened paper, pro-
duced contractions of the muscles. To find out whether
the difference of effect was referable to the different con-
ducting power of the slips placed under the nerves, I in-
stituted by means of galvanic experiments, in which I
employed two metals, a comparison between the conduct-
ing power of the skin of the frog, and that of the moistened
paper, and ascertained that they differed essentially.
The frog's skin conducted much better than the moisten-
ed paper, which is but an imperfect conductor. It is need-
less to enter into the detail of these experiments, M. de
Humboldt having already established the fact, that the
conducting power of animal substances, is superior to that
of vegetable matter in its recent state, and having shewn
that this difference does not depend on the water which
they contain, but on the nature of the organized structures
themselves. These experiments are easily conducted ; they
are founded on well known principles, and they appear sa-
tisfactorily to prove that, cseteris paribus, the muscular
contractions, produced by the contact of a solid body with
a nerve, are much less considerable, or even wholly ab-
sent, when the nerve, instead of being insulated, is in
communication with a good conductor, and it would seem
to follow as a legitimate conclusion, that these contractions
are dependent on electricity.
ON ATMOSPHERIC ELECTRICITY. BY M. POUILLET.
Various theories have been formed by meteorologists to ac-
count for the electricity sensibly present in the atmosphere.
Of these, Volta's was, perhaps, the only plausible one.
That philosopher was induced to believe, that bodies, in
passing from one state to another, undergo a change in
their electric condition, and supposed that the electricity
lost in storms, was constantly being renewed by that pro-
duced by evaporation perpetually going on from the surface,
as well of the land as of the water.
The recent and interesting researches of Pouillet, were
instituted, not merely to ascertain the truth of the Italian
Professor's hypothesis ; he was also desirous of discovering
the efficacy of another cause, which he believed to be of
no small importance in the production of electricity, and
of bringing to proof a theory of his own, relative to the dis-
tribution and accumulation of this principle in the atmo-
sphere.
Numerous and various experiments have brought him
to the conclusion, that the mere passage [of a body, from
the solid form to a state of vapour, is unaccompanied by
the development of electricity, that the result is similar,
when vapour is condensed into the liquid, or solid form.
He conceived that Volta, though too accurate an observer
to be mistaken as to the fact of the presence of electricity
in his experiments, was, nevertheless, deceived as to the
cause of its production, by the formation of carbonic acid,
which mixed with the vapour of water, and complicated his
experiments.
In 1782, Volta, Lavoisier, and Laplace, shewed, that
electricity was developed during chemical action, but as
APPENDIX. 317
experiments relating to this point, are liable to afford dif-
ferent and contradictory results, from slight differences of
circumstances, the question has been regarded as undecided.
It became, on this account, an object of special attention
with M. Pouillet. He finds that in the combustion of
charcoal, there is an unequivocal production of electricity,
that the acid produced is in the positive state, whilst the
charcoal always becomes negative. It is necessary, in order
uniformly to obtain the same result, that the combustion
should take place only at the upper part of the piece of
charcoal, and by no means extend over the whole of it ;
otherwise the contact, both of the charcoal and of the car-
bonic acid, with the plate of metal destined to receive the
electricity, will render the experiment irregular. To dis-
cover whether the electricity, rendered evident in the pre-
ceding experiment, was to be attributed to chemical action,
or to the conversion of the charcoal from the solid to the
gaseous, he examined the flame produced by the combus-
tion of hydrogen. The external part of the flame con-
stantly exhibits vitreous, and the interior resinous elec-
tricity. Thus, by the act of combustion, the combustible
becomes electrified negatively, and the body which is ac-
tually burning, becomes positively electrified, whilst a trans-
fer of electricity is taking place between the molecules, which
are combining, and those which are about to do so. This
fact is supported by a great number of experiments on the
combustion of phosphorus, sulphur, the metals, alkohol,
ether, fat substances, and vegetable matter.
As plants during vegegation exert a chemical action on
the atmosphere, sometimes converting its oxygen into car
bonic acid, and at others, decomposing the carbonic acid
already existing in it, the idea suggested itself, that if
electricity were developed in the process of vegetation,
their very extensive operation would warrant one in attri-
318 APPENDIX.
buting to them a considerable portion of the electricity of
the atmosphere.
To investigate this subject, Pouillet examined the vege-
tation of seeds in an insulated situation, having a condenser
connected with the soil. Till the germs appeared at the
surface, no signs of electricity could be detected, but as
vegetation advanced, it became very evident. For the
success of this experiment, it is necessary that the air
should be in a state of considerable dryness; when this
does not happen to be the case, the apartment must be ar-
tificially dried by quick lime or some absorbent. It is
obvious, that the soil could not acquire one electric state,
without the opposite state, in a corresponding degree being
communicated to the atmosphere.
If, then, a languid vegetation, on a surface of five or six
square feet, be capable of producing very decided effects,
may we not reasonably conclude, that the influence of the
same cause, operating over a large portion of the surface of
the earth, is fully adequate to the production of many of
the phsenoniena, which we observe.
A second memoir, by the same author, carries this subject
still further, and exhibits other causes besides the process
of vegetation, which contribute to supply the atmosphere
with electricity. In the first memoir he had shewn, that
when two bodies combine, electricity is developed ; in the
second he proves, that similar phsenomena attend the sepa-
ration of bodies which were previously combined, and he
applies this fact to the numerous instances of decomposition
which nature is spontaneously producing on the surface
of our terraqueous globe.
Pouillet, in his experiments connected with this inquiry,
employed two processes — the first resembles that adopted
by Saussure, in his experiments on evaporation, and consists
in connecting one of the disks of the condenser with the
APPENDIX. 319
heated vessel, in which the subject of the experiment is to
be placed. By the other process, the heated vessel is dis-
pensed with, and he makes use of one of Fresnel's large
lenses, to heat the body whilst it rests on a plate of platina.
It should be remarked, that when vessels of copper, iron,
or of other materials, on which the substance under exami-
nation can act chemically are employed, the result will be
a complication of effect, by which the phenomena will some-
times be heightened, and at others neutralized.
The results of these experiments are,
1. That by mere evaporation, whether rapid or short, no
signs of electricity are produced.
2. That evaporation from an alkaline solution, however
recent, whether it be of soda, potass, baryta, or strontian,
leaves the alkali electrified positively.
3. That when other solutions, either saline or acid, are
employed, evaporation leaves the body which was combined
with the water, electrified negatively. Of the numerous
saline solutions which were essayed, that of muriate of soda
was naturally the one which excited the greatest interest.
It formed no exception to the rule. Hence it can hardly be
doubted, that evaporation from the surface of the sea forms
one of the most important sources of atmospheric elec-
tricity. Even lakes and rivers must have their influence,
since their waters are never perfectly pure.
320
EXTRACT FROM AN ESSAY ON SOME OF THE PHENOMENA
OF ATMOSPHERIC ELECTRICITY. BY LUKE HOWARD,
F.R.S., &c. Read before the Askesian Society in 1800.
From an attentive examination of Read's observations, I
have been able to deduce the following general results.
1. The positive electricity common to fair weather often
disappears, and yields to a negative state before rain.
2. In general the rain that first falls .after a depression
of the barometer is negative.
3. Above 40 cases of rain in 100 give negative electricity,
although the state of the atmosphere is positive before and
afterwards.
4. Positive rain in a positive atmosphere occurs more
rarely ; perhaps 15 times in 100.
5. Snow and hail unmixed with rain are positive almost
without exception.
6. Nearly 40 cases of rain in 100 affected the apparatus
with both kinds of electricity ; sometimes with an interval
in which no rain fell, so that a positive shower was suc-
ceeded by a negative, and vice versa; at others the two
kinds alternately took place during the same shower, and
it should seem with a space of non-electric rain between
them.
The regularity with which the latter phenomena some-
times occurred, seem to furnish a clue for explaining some
of the preceding cases, and indeed for constructing a hy-
pothesis of local rain. I shall submit to the consideration
'
APPENDIX. 321
of the Society my conjectures, in the confidence of their
meeting with a candid examination, and on this account I
ought to add, that the latter part of my investigation of
Read's Journal has been performed with this supposed clue
in my hands ; that I have met with some facts to which it
is not applicable, and am, therefore, willing to distrust its
guidance, except on those points were it applies directly
to the phsenomena. The members may do well to compare
what I shall advance with the Journal at large, since ob-
jections may occur to them which escaped me.
Let fig. 1. represent the area on which a local shower
falls ; a. being a certain portion in the centre in which the
rain is charged positive ; b. b. a surrounding portion in
which the positive charge terminates, and which may be
considered as occupied by non-electric rain ; c. c. the re-
mainder of the area surrounding the two former portions,
and occupied by a negative charge, which also extends into
the surrounding atmosphere, e. e. to a distance propor-
tioned to the intensity of the central positive charge. The
non-electric boundary of the negative charge is represented
by the line, d.d. d. d. Without this line, the atmosphere
is supposed positive as usual when free from clouds. In a
shower so constituted, the electric signs obtained by obser-
vations made in a single and fixed station, (as Read's were,)
would be subject to the following variations.
1. The central area remaining the whole time over the
instrument, the observation would be positive ; and
2. The circumferential area doing the same, it would
be negative. Many cases in Read will be thus explained,
and it is favourable to the hypothesis, that the positive
observations are to the negative nearly as 1 to 3 ; but, on the
other hand, this does not account for the fact of several
showers being negative in succession, nor for the relation
Y
322 APPENDIX.
which seems to obtain between depressions of the barometer
and negative rain.
3. The rain beginning with the central area over the
instrument, and ending with the circumferential, the obser-
vation would be first positive, then negative after an inter-
mission of the electric signs.
4. The circumference being first examined, and the rain
ceasing by expenditure during the charge from the centre ;
the order would be the reverse of 3.
5. The. cloud passing over in the zenith of the appara-
tus, and the latter describing under it the line f. f., all
the appearances would agree with those cases in which a
shower commencing with negative electricity, shews itself to
be positive in the middle and terminates as it began, with
negative.
6. But the line which the apparatus may be considered
as describing under the cloud, in consequence of irregu-
larities either in the motion or form of the latter, may re-
semble the curve, g. f. ; and after having entered the
shower or commenced within it, may pass and repass the
non-electric boundary several times during its continuance.
It may also happen to commence or to terminate in the
latter. This will serve to explain some of the most irregu-
lar cases in the Journal.
7. It frequently happens, that the apparatus is charged
in consequence of rain falling at such a distance, that not
even the skirts of the shower come over it. This is par-
ticularly the case in thunder storms, and the phsenomena
are such as ought to take place, according to the hypothesis,
when the centre of the mass of clouds and rain (which elec-
trically considered form one aggregate) passes at a certain
distance from and parallel to the line, f. k., on which we
now suppose the apparatus to be. The latter then loses its
positive charge at i., and presently acquires a negative, which
APPENDIX. 323
becomes more intense as the rod enters further into the ne-
gative area, and dies away as it quits it, till at k. it be-
comes extinct.
8. If the station of the observer, during a thunder storm,
happened to be in any part of the circle, d. d. d. d., he might
be unable, if the time devoted to the observation were short,
to obtain any signs whatsoever from his apparatus, although
he might both see and hear the successive discharges in
the horizon.
I have witnessed such an occurrence myself, and I sus-
pect that what Read has noted under June 22, 1790, is
from the same cause. The centre of the storm in this case,
appears to have been about Salisbury, distant 80 miles.
When we consider the elevation which was necessary to
render even the extremity of this storm visible at Knights-
bridge, we shall not find this distance too great for the
semidiameter of the total area in which its effects might
be sensible with a good instrument.
To some of the cases these explanations seem clearly appli-
cable ; in others there is room for correction by future observa-
tions, which would be far the most instructive if conducted in
concert, by several persons at different stations, within the
compass of a few square miles. It will be readily seen, that I
have made the accumulation of positive electricity in a certain
portion of the atmosphere, the basis of the whole system.
The remainder follows as a necessary consequence from the
known laws of electricity. But the production of positive
electricity is not necessarily confined to the centre of an
aggregate of clouds, nor its effects to a lateral direction
only. Cases may occur in which one extremity of the ag-
gregate may be positive, and the other in consequence,
negative ; there may be positive electricity in a certain stra-
tum of the atmosphere, and from hence may result a ne-
v2
324
APPEN D1X.
gative counter-charge in a contiguous stratum above or
below. In continued rain such a distribution most pro-
bably obtains, but we must have more observations to be
able to prove it. Our present object is to shew how a local
shower is organized, and if possible to trace its immediate
origin to electrical causes; for it is in vain that the principles
of chemistry alone are appealed to in this case. Let us see
therefore how it happens, that the centre of a shower is
often strongly positive. The clouds originate from vapour,
which is first formed in contact with the earth. It is not
therefore then electrified, except the surface on which it is
formed be at the time super-induced. But the latter is the
proper effect of impending clouds, and although a truly
electrised vapour may be thus formed, and being condensed,
may constitute a part of the system of clouds in a thunder
storm, yet our present enquiry goes further : we want to
account for the super-inducing charge.
It would be a difficult undertaking to ascertain by expe-
riment the electrical state of vapour, and of the surface on
which it originates in the natural process. Experiments
have been made on insulated substances at high tempera-
tures, the results of which, even if more conclusive, would
be quite inapplicable to this case. I shall therefore offer
some conjectures on the origin of atmospheric electricity,
which will in the first instance proceed on the supposition
that vapour is originally non-electrised. A body in order to
be charged must be first insulated, and the charge will
continue during perfect insulation, but the latter seems
unattainable. There is always a small degree of conduct-
ing power in the very atmosphere when at the maximum
of dryness, and this is greatly augmented by what is called
moisture, by which I understand, diffused and suspended
(not elastic and gaseous) water.
We can scarcely imagine a body more perfectly insulated
APPENDIX. 325
than the first particle of water which, separating- from va-
pour that has ascended into the higher atmosphere, begins
to obey the law of gravity. There are two sources from
whence such a particle may obtain an electric charge, viz.,
the surrounding air, and the vapour out of which it was
formed, and which may, though in itself non-electrified,
afford to the water, now reduced many hundred-fold in vo-
lume, a real positive charge. Appearances, likewise, are
much in favour of the opinion, that the precipitation of
water in the higher atmosphere is sometimes effected by a
double affinity, in which electric air and gaseous water are
mutually decomposed, the former seizing the caloric, the
latter the electric fluid.
At all events we are certain of the fact, that clouds are
insulated and charged conductors. Franklin supposed,
that clouds arising from the sea were positive, those from
the land negative, and that their rencounters in the air
were the cause of thunder storms. Kirwan, and others,
go a little further, and say, that a positive cloud (become
such in the way I have stated) may affect another with a
negative state by its approach, and thus attract it to form
rain. But all these explanations fall short of the phse-
nomena. Had this been all the process, we should have
known nothing of the electricity of rain, for a negative and
positive cloud would unite in those proportions only, which
should form non-electric rain. *#'.*■#
The reader who may be curious further to pursue these
highly interesting meteorological considerations, is referred
to a new edition of Luke Howard's work on the Climate of
London, now in the press, and in which will be found the
whole of the paper of which the preceding is an extract,
together with much new and important matter on collateral
subjects.
I have been induced to give the preceding extracts, from
326 APPENDIX.
the idea that they may tend to throw some light on the
very interesting, but still imperfectly understood subject
of the influence of electricity upon vital phenomena.
The observations of Prevost and Dumas, contained in
the Appendix, relate to the supposed operations of electri-
city, as an agent in some of the functions carried on within
the body, and more especially in conjunction with muscu-
lar contraction. The views which they contain are ex-
tremely ingenious and interesting, but I must confess my-
self unable fully to adopt them.
The experiments and operations of Pouillet, respecting
the development of electricity by the process of vegetation,
led me to conclude, that a similar development must take
place in the production of carbonic acid by the respiration
of animals, and also by the vinous fermentation of fluids.
My attempts to demonstrate the correctness of this sus-
picion have not yet been successful. I hope hereafter to
pursue the enquiry, and in the mean time I shall relate a
few facts which seem to bear on the subject. It has long
been observed that individuals of highly sensitive consti-
tutions are concious of uneasiness, sometimes amounting
to absolute pain, or the disturbance of function during the
existence of a thunder storm ; this is by no means neces-
sarily connected with fear, or other mental emotions, pro-
duced by the loud sound and vivid light, or any other
phenomenon cognizable to our senses. The influence of
which I am speaking is frequently felt before the storm has
commenced, and has occasionally been experienced by in-
dividuals so far removed from the skirts of the storm, as
not to be conscious of its existence at the time, except by
the intimations afforded through the symptoms in question.
Such cases seem to be analogous to the instance alluded
to in the paper of Luke Howard, in which Read's appa-
APPENDIX. 327
ratus, set up at Knightsbridge, for the examination of aerial
electricity, was influenced by a storm supposed to have
passed over Salisbury. Persons who watch the habits of
leeches, have frequently remarked their peculiar agitation
when the electric state of the air is disturbed by storms,
and it is believed by persons accustomed to the rearing
of poultry, that storms sometimes have an injurious, and
even a fatal influence upon eggs undergoing incubation*
It is a generally admitted fact, that liquors undergoing
the vinous fermentation, suffer a great disturbance in this
process during the existence of a thunder storm. These
facts taken together, led me to question, whether the
negatively induced electricity may not have a tendency
to disturb the production of carbonic acid, which Pouillet
has shewn to escape in a negatively electric state.
We have as yet but few well-conducted and satisfactory
observations, respecting the influence of an artificially dis-
turbed electric state upon living organized beings. Some
observations have been made with reference to vegetable
physiology, and as this may often be appealed to for as-
sistance, in our attempts to elucidate the more difficult
subject of the physiology of animals, it may not be amiss
briefly to relate them.
With respect to dead animal and vegetable matter, the
experiments of electricians completely tally with what has
been observed to be the effect of the electric disturbance of
the atmosphere. The observations of Achard of Berlin
support this assertion. They are briefly noticed in the
Encyclopaedia Metropolitana, from which the following
short statement is extracted.
It is a well known observation, that after a storm, flesh,
either raw or boiled, acquires a putrid smell, which, in the
latter, is particularly acid. It is known, also, that grain
328 APPENDIX.
suffered to ferment for the purposes of brewing or distilling,
undergoes, during stormy weather, very sudden and per-
ceptible changes. On such occasions, it is often extremely
difficult to observe where the first degree of fermentation
ceases. It passes so speedily that the second degree, or the
acetous fermentation, takes place before one is aware of it.
To ascertain, therefore, whether the electric matter, which,
during stormy weather, is so abundant in the atmosphere,
has any share in these phaenomena, the following experi-
ments were made.
A piece of raw beef was cut into three parts. One of
these parts was electrified positively for ten hours without
any shock ; a second was electrified negatively for a similar
time ; and the third was not electrified at all. The three
pieces were left in the same apartment, exposed to the same
degree of heat. When examined next day, both the pieces
which had been electrified appeared to be tender, but were
free from the least bad smell. On the fourth day, the elec-
trified flesh had an intolerably foetid smell, and that which
had not been electrified began to smell a little.
M. Achard repeated these experiments with boiled veal.
That which was electrified had, the next day, an acid smell,
and an unpleasant taste ; but that which had not been elec-
trified, continued sweet for three days, and only on the
fourth day began to have an acid smell.
Several birds were killed by electric shocks, and others
were deprived of life, by sticking a needle through their
heads, and then placing all in the same temperature, they
were covered with glass receivers in order to preserve them
from insects. Observing the gradual progress of corrup-
tion in both sets, M. Achard plainly perceived, that it took
place much sooner, and advanced more rapidly in those
killed by electric shocks, than in those deprived of life by
APPENDIX. 329
the needle. . In those also, to which a stronger shock had
been given, the degree of corruption was far greater than
in the others.
Van Marum made a similar observation with respect to
the rapid decomposition of eels, which had been killed by
electricity.
It clearly follows from these experiments, that electricity
accelerates corruption, and that the putrefaction of flesh
after a storm, must be ascribed solely to the more abundant
accumulation of the electric matter at that time. M. Achard
saw that this was the case in regard to several persons
killed by lightning. The body of a farmer, who lost his
life in this manner, between five and six o'clock in the
evening, emitted next morning a very perceptible foetid
smell, which in the evening was totally insupportable.
Having stated these effects of electricity on dead vege-
table and animal matter, which are sufficient to shew its
power in modifying and accelerating chemical changes, we
may now inquire after what is known of its influence when
life is present. We shall commence with vegetables, in
which the direct physical effects are less complicated, from
their not being mixed up with what may be regarded as its
moral effect on a highly sensitive nervous system.
It is well known that trees may be killed by lightning,
but in these instances there is so much violence and de-
struction of texture, that we can draw no conclusion from
them as to the influence of electricity. Cavallo, though
he disputes the correctness of the statements of some elec-
tricians, with respect to the influence of electricity on plants,
has shewn that the bahandna impatiens is killed by shocks
which are too slight to impair the structure. A branch of
this plant died the day after receiving the shock — the
branches of other plants survived longer. A laurel branch
lived fifteen days and that of a myrtle a whole month.
330 APPENDIX.
VanMarura and Nairne confirm the deleterious effects of
electric shocks, shewing that they kill some plants and pre-
vent slips from taking root and budding.
If electricity in the form of shocks has the power of de-
stroying vegetable life, we may reasonably presume, that a
less violent application of this agent would produce some
sensible modifying effect. The first experiments upon the
application of electricity to living vegetables, appear to
have been made by Mainbry, in Edinburgh, in the year
1746. In the autumn of that year, he subjected two myr-
tles to gentle electric action during one month, and ob-
served that they subsequently put forth leaves earlier than
similar trees which had not been electrified. The Abbe
Nollet, Jallabert, Boze, Menon, Dr. Carmoy, the Abbes
D'Ormoy and Bartholon, maintain the power of electricity
as a stimulant to vegetables ; the last named experimenter,
in particular, has been extremely zealous in this enquiry.
He regarded electricity as a most powerful stimulant to ve-
getation, and recommended its practical application in hor-
ticulture, for which purpose he contrived an apparatus,
called electro-vegetometer, with which he employed artifi-
cial excitation. He proposed the direction of atmospheric
electricity to the same object, and believed that he pro-
duced some good effect by watering plants with water
charged with electricity. Although there can be little
doubt, that the Abbe's enthusiasm in his subject led his
imagination to the over-straining of facts, yet it is by no
means improbable, that there is more truth in his observa-
tions than Cavallo and Ingenhouse are disposed to admit.
It has been asserted, that plants grow with encreased vigour
in the neighbourhood of thunder rods. It might have been
supposed, that if plants in general are influenced by elec-
tricity, those plants which offer the most striking proofs of
sensibility would be the most signally excited by it. Van
APPENDIX. 331
Marum was, therefore, led to try its effects on the mimosa
pudica, and on the hedysarum gyrans, but he could not
detect that their movements were positively affected by it.
It will be well to bear this fact in mind, when considering
the motions of animals and vegetables.
The fatal effects which violent discharges of electricity
produce on animal life, are more notorious than in the case
of vegetables. Scarcely a summer passes without nu-
merous instances occurring in which man and other animals
are killed by lightning. The discharge of an ordinary bat-
tery is sufficient to kill insects and worms, and the shock
from a tolerably large one will kill mice. It is truly sur-
prising to see how instantaneously some of the lower ani-
mals, which are remarkably tenacious of life, are completely
deprived of it by the electric shock. I once discharged a
battery of considerable size through a common earth-worm,
which would in all probability have shewn signs of life long
after minute division. Its death was as sudden as the
shock, and the semi-transparent substance of the animal
was changed like albumen which has been exposed to
heat.
The artificial accumulation of electricity in batteries of
very large size, has been found sufficient to kill not only
rabbits, but even large and vigorous hogs, a fact which
was completely proved by my friend Charles Woodward in
the presence of Dr. Scudamore.
It may now be interesting to notice some of the pheno-
mena induced by electricity, within those limits which are
compatible with life. With the hope that this short expo-
sition may tend to assist, either in the extension or appli-
cation of our present knowledge of the subject, I shall
endeavour to class these phenomena under the following
heads.
332 APPENDIX.
Electric tension — its effects on the system generally — -
difference of the positive and negative charge — its effects
on particular functions, such as circulation, exhalation, and
secretion and respiration — the effects of the transmission of
shocks — of a continuous stream — sparks — aura — appli-
cation.
It is well known, that that state of the atmosphere which
is unfavourable to electrical experiments from its being ad-
verse to the insulation, and consequently to the electric
tension of bodies, is also ungrateful and oppressive to
our feelings; and that precisely the opposite effect is ex-
perienced in clear and frosty weather, and in other states
of the atmosphere which facilitate the working of electri-
cal machines. We might regard these as coincident, rather
than connected facts, if it had not been observed that an
artificial repletion with electric fluid produced a similar
effect in exhilarating the spirits, a fact for which, with many
others here related, I am indebted to my friend Charles
Woodward of Islington, a gentleman who has long and
successfully devoted his attention to electricity.
This fact conducts us to the enquiry, whether there is
any difference, as far as the influence on the animal eco-
nomy is concerned, between a positive and a negative charge.
Here, I regret to say, that I have very little of a decisive
character to bring forward, yet I may state on the same
valuable authority which I have just given, that a negative
charge continued for about half-an-hour, has caused an
unequivocal perception of languor and oppression. Do we
not find an obvious parallel to this experiment in the power-
fully oppressive and sometimes distressing influence of
which highly sensitive individuals are conscious on the
approach of a thunder storm, or during the prevalence of a
north-east wind, which is characterized as peculiarly un-
APPENDIX. 333
healthy and productive of a sensation of dryness and cold,
unaccompanied by a corresponding depression of the ther-
mometer? It was shewn, in the preceding article on Atmo-
spheric Electricity by Luke Howard, that a highly electri-
fied thundercloud is surrounded to a considerable extent by
atmosphere which is in a negative or neutral state. The
north-east and east winds are often in a similar condition.
Except in cases of the transmission of a strong electric
current through some part of the nervous system, which
produces an instantaneous disagreeable, or even fatal effect,
it would seem that a considerable portion of time is neces-
sary for the production of anything like a sensible effect
from disturbance of the electric equilibrium. Leeches, as I
before observed, are said to be highly susceptible to very
slight alterations in this respect. I was, therefore, led to
enquire what would be the result of a great, but sudden and
transient encrease of their electric tension. I was careful
to avoid subjecting their bodies to the direct effect of a
spark or shock. I placed several active healthy leeches in
a glass vessel containing water, which being thus insulated,
I kept for a little while strongly electrified positively, but
without producing any sensible effect. Precisely the same
result attended a negative charge. I next tried what would
be the effect of converting the vessel containing water into
a Leyden jar, by applying a partial coating of tin-foil out-
side. Having given a moderate charge, I suddenly restored
the equilibrium by discharging the jar, but I could not
perceive any unequivocal appearance of uneasiness in the
leeches, which remained perfectly healthy for several days,
after which they were no longer watched.
Although the statements which are made respecting the
effects of increased electric tension upon the circulation at
first appear contradictory, a little consideration will satisfy us,
that these decrepancies are analogous to such as attend the
<j
334 APPENDIX.
application of other stimulants. Walker and Carpue have
both recorded, that the blood flows more freely from an
opened vein when the patient is electrified. The force of
the circulation must, therefore, have been increased. Ca-
vallo was assured by an experienced medical electrician,
that in a diseased state of body, an evident acceleration of
the pulse is often observed to result from the application of
electricity. Van Marum took considerable pains to inves-
tigate this point. Eleven persons were selected, and the
experiment was repeated four times upon each, both with
positive and negative electricity. These persons were
placed in a room which was at such a distance from the
machine, that they could not hear the noise it made in turn-
ing ; they were insulated, and the pulse of each was felt
when the machine was in motion, as well as when it was at
rest, (which last circumstance was unknown to them,) and
the beats were counted by a good observer, provided with
an excellent watch. In some cases a few more beats were
observed, but, on the whole, there was no important acce-
leration. In general, however, there was great irregularity
in the pulse, both during the time the persons were electri-
fied, and during the time the machine was at rest.
There can be little doubt, but that the individuals who
were the subject of this experiment, were much influenced
by mental emotion, and it seems very probable, that the
interruption in the application of the electric influence, con-
tributed to vitiate the result.
The following observations on this subject were commu-
nicated to Charles Woodward, Esq., by his friend F. Smith
of Fordham, and are confirmed by his own experience.
The pulsations were carefully watched before electrifica-
tion. The electric influence was passed through each per-
son without sparks, and continued fifteen minutes, after
APPENDIX.
335
which, while the fluid was still passing through them, the
pulsations were again noticed.
Patient.
Pulse at first.
Reduced to
1
80
75
2
64
51
3
90
76
4
66
61
5
70
60
6
74
62
7
65
58
8
100
90
These individuals were all males.
Electrification for less than ten minutes did not in gene-
ral appear to affect the pulse.
It may be imagined, that in the subject of this experi-
ment, the previous apprehension had raised the pulse, which
subsided when they were quietly placed on the stool.
This objection appears to be met by two cases of ague,
in which the pulse was soon reduced by electricity thirty
beats per minute during the paroxysm. As one of these
instances occurred in the electrician's own person, it cannot
be supposed that the pulse had been raised by trepida-
tion.
When the Abbe Nollet had shewn, that the evaporation
of volatile bodies is promoted by an electric charge, it be-
came a matter of curiosity, whether it had any influence
on the insensible perspiration of animals. Many experi-
ments were made which seemed to prove, that that func-
tion was increased whilst the animals were electrified.
Van Marum, who afterwards undertook to examine this
question, came to a different conclusion.
336
APPENDIX.
For the purpose of ascertaining the increase of insensible
perspiration, he employed a very delicate balance ; one
scale of which was insulated by means of a silk cord. On
this scale he placed a boy, eight years of age, connected
with the conductor; and the balance was brought to a
state of equilibrium. He then ascertained the loss of
weight sustained in half an hour, before the boy was elec-
trified, and found it to amount to 280 grains. By a simi-
lar experiment on another occasion, the loss of weight,
before being electrified, was 330 ; and after exposure to
electricity only 310. A girl of seven years old lost, before
being electrified, 180; and when electrified, 165 grains.
A boy of eight years and a half lost, before being electri-
fied, 430 ; and when electrified, 290 grains. Another of
nine years unelectrified, 170 ; electrified, 240. As the
last boy was exceedingly quiet during the experiment, it
was thought that the increase was the consequence of elec-
tricity; on this account he was several times subjected to
the experiment, and the results were : in the unelectrified
state, 550 ; in the electrified, 390, 300, 270, 550, and 420.
If we consider these experiments of Van Marum, in con-
junction with the light thrown on the subject of perspira-
tion, by the observations of Dr. Edwards, given in this
volume, we shall have no difficulty in perceiving, that they
by no means warrant the inference, that increased electric
tension is unfavourable to perspiration. It will be remem-
bered, that it was proved by Dr. Edwards's experiments,
that the loss by perspiration in a given period, progressively
diminishes as the body perspiring recedes from the point of
saturation. Circumstances may for a time produce appa-
rently contradictory results, which, when investigated, ra-
ther confirm than invalidate the principle. It can scarcely
be doubted, that electricity promotes evaporation from the
APPENDIX. 337
surface of inanimate bodies, but it must still be regarded
as an undecided question, in what manner it effects the
insensible perspiration of animals. From facts recorded by
medical electricians, it appears that some secretions are
promoted by electricity, but it has been found, both in
Germany and in this country, that the excessive secretion
of urine in diabetes has been repressed by electricity applied
in the form of galvanism to the loins. The function of
absorption appears, in some cases, to be salutarily excited
by electricity. It has been successfully applied to tumours,
with a view to promote their dispersion. In one case, which
occurred to Philip Smith of Fordham, sixteen applications
of electricity, employed for another object, had the gratifying
effect of removing a chronic hydropic affection. Even
ovarian dropsy, than which no variety is regarded as less
under the controul of medical means, seems, in some in-
stances, to have yielded to its influence. Although there
is no function more important to life, or more intimately
connected with other functions than respiration, and none
which possesses so decidedly chemical a character, and
consequently bears so obvious a relation to the changes of
inorganic matter, to which electrical phsenomena are acces-
sary or concomitant ; yet, we are still perfectly in the dark
as to the relations which may exist between this function
and electricity. I have already mentioned this subject as
one which I have in vain wished to investigate, and, there-
fore, have little to offer respecting it. There is, however,
one circumstance which I may mention, not only because
it tends to shew that a connection between respiration and
electricity is not purely imaginative, but because it may
serve as a hint for one of the modes in which the enquiry
may be pursued. It has been asserted, that hens hatch ^
their eggs after a shorter period of incubation, when they
and their nest have been insulated and kept in a state of
z
338 APPENDIX.
state of increased electric tension. Now the only function
by which the eggs are in relation with surrounding objects,
is that of respiration, carried on by the vascular membrane
within the shell, through the pores of which the atmo-
spheric influence is exerted.
The passage of the electric influence is probably pro-
ductive of no less important effects on the animal economy,
than increased tension. In some instances their effects
may be combined. The sensation produced by the electric
shock, is the most notorious and perceptible effect which
electricity produces in the system, yet it is so transient,
that except in those cases in which it has been of sufficient
force to be injurious to life, it is generally limited to the
inappreciably short interval occupied by the discharge. The
rapid succession of sparks received at one part of the body,
and given off at another, the individual being insulated for
the purpose, is an approximation to a continued current of
electric influence, and though much milder than the shock,
as far as the feelings are concerned, exerts a much more
powerful influence on the system and is of far greater ser-
vice as a medical application. This is still more strikingly
the case, when the sparks, whether given or taken, are re-
duced to a very small size, though encreased in number by
bringing the metallic ball nearly into contact with the per-
son, a thin piece of flannel alone intervening between it and
the skin. It is in this form that the electric current has
been long and very successfully employed in a variety of
maladies by C. Woodward.
The electric aura affords the means of applying a yet
more equable and continuous current, the effects of which
appear to be proportionately superior, notwithstanding they
are even less perceptible to the senses. The reality of this
influence is confirmed by pheenomena connected with dead
inorganic matter, as well as by its effects on parts of the
APPENDIX. 339
living- system. All attempts to make the compass deviate
from the magnetic meridian by means of common electri-
city, as CErsted had done by galvanism, had been unsuc-
cessful, until C. Woodward conceived the idea of applying
electricity in the form of aura to the wire destined to pro-
duce the deviation. This plan he found completely answer,
and repeatedly exhibited it some time before Dr. Wollaston,
by whom the fact has been announced, appears to have had
his attention arrested by it. The hand of a lad had been
long permanently and powerfully clenched in consequence
of a blow from a hammer. Every mode of treatment com-
pletely failed, until the electric aura was applied, which
effected a perfect cure.*
The transmission of the electric influence seems to act
directly upon the nervous system of animals. I have al-
ready alluded to the sensation which it excites, and which
is manifestly to be referred to the nervous system. Defects
in the senses of feeling, seeing, and hearing, and distressing
neuralgias, have been relieved by its influence on that sys-
tem. Through the medium of the nerves, the electric cur-
rent acts powerfully on the muscular system. This is most
conspicuously seen in recently dead or expiring animals, but
it is also evident in many cases of paralyzed limbs. Some
of the phasnomena connected with this part of the subject
are so striking, that it is by no means surprising that some
physiologists should have regarded the natural influence of
the nerves in the production of muscular motion, as of an
electric character. Porret, Prochaska, Dr. Wollaston, and
others, have endeavoured to shew by analogy, that secre-
tion is effected by an electric current. Dr. Young has
proposed a similar theory. Drs. Wilson Phillip and Hast-
ings have laboured to prove, that the fatal effects of the
* See a cast of this contracted hand in the Museum of Guy's Hospital.
z2
340 APPENDIX.
division of the eighth pair of nerves depend on the con-
sequent interruption to secretion, which the application of
electricity to the divided nerves will in a great degree re-
store and maintain. Dr. Milne Edwards opposes this view,
and contends that an equally advantageous effect is pro-
duced by the mere mechanical excitation of the divided
nerves.
The following fact is of no less practical importance than
physiological interest. I am informed by my friend C.
Woodward, that it is an essential rule in the application of
electricity to medical purposes, that the current should pass
in the direction from the trunk to the extremity of the
affected limb. In this way it often affords prompt relief;
but if the current be reversed, the evil is aggravated.
The experiments which I have next to relate appear so truly
wonderful that, but for the good authority by which they are
supported, I should feel unwilling to give them a place here.
The remarkable results which accompanied them can
scarcely be explained as coincidences, and they appear to
open the way to new and important inquiries ; but nu-
merous observations and experiments must be made before
we can be warranted in drawing any certain conclusions on
the subject. P. Smith of Fordham, to whose experiments
I have already alluded, having relieved numerous patients,
labouring under gout, rheumatism, and other painful affec-
tions, was induced to try the effects of electricity upon in-
termittent fevers. He intended to employ it as the cold
stage was coming on, but his first patient having mistaken
the time of the accession of the fit, he did not apply it until
the hot stage had commenced : he insulated the man, and
caused him to receive sparks at the epigastric region, while
he took them from him along the course of the spine ; the
pulse was speedily reduced thirty beats per minute. The
APPENDIX. 341
next patient was electrified on the coming on of the chill,
which it immediately checked ; nevertheless the hot stage
ensued, when electricity was again applied, and, as in the
former case, it reduced the pulse thirty beats — there was
no return of the paroxysm, but the application of electricity
was repeated for some days. Another case of ague, which
had lasted four months, and obstinately resisted bark,
arsenic, and other medicines, was quickly cured by a few
applications to electricity. The most extraordinary circum-
stance remains to be mentioned. P. Smith himself had
held the ball, with which he took sparks from his first
patient, during the hot stage. In the same evening, he
found himself unwell ; but had no suspicion of the nature
of his complaint, until the recurrence of the paroxysm con-
vinced him that he had become the subject of ague. He
allowed these to recur to the seventh time, before he at-
tempted the cure by electricity, which was speedily effected,
being the second case already alluded to. As he had never
been the subject of ague, and had not been more than
usually exposed to causes calculated to give rise to it, he felt
persuaded that it had been communicated to him by elec-
tricity from his former patient.
In order to ascertain this, he was desirous of trying ex-
periments on some persons labouring under a disease which
was inflammatory, but not considered infectious ; he, there-
fore, had one of his men vaccinated. On the seventh day,
the man was placed on the insulating stool, and connected
with the positive conductor; a small incision was made with
a lancet in the pustule, and an incision was also made in
the arm of a lad with a new lancet ; a wire four inches long
was passed through a glass tube, one end of which touched
the pustule on the man's arm, and the other the incision
on the boy's arm — the electrification was continued for
eight minutes, when the boy was removed. His arm was
342 APPENDIX.
daily examined, and it was found, that he was as com-
pletely vaccinated by electricity as any person could be by
the usual mode. My friend afterwards endeavoured to
communicate the virus to two girls, by passing the electri-
cal fluid from the pustule on the boy's arm, who had been
vaccinated by electricity, to incisions made in theirs. For
three days the medical gentleman supposed it had taken
effect ; but, on the fourth day, all appearances of vaccina-
tion died away. These girls were, however, afterwards
vaccinated in the usual way in four places, two of which
died away, and the other two took but very slightly. My
friend Charles Woodward afterwards repeated this experi-
ment upon an infant, the child of one of his friends, but
with this difference, that he did not allow the conducting
wire to come in contact with the child's arm. The electric
fluid was consequently transmitted in the form of small
sparks. The disturbance which these produced, though
trivial, prevented the application from being prolonged for
the full time, which my friend would have wished ; inflam-
mation however succeeded, and, until the sixth day, was
such as to induce the medical attendant to believe, that the
vaccination had been complete; from that day, however,
the pustule died away.
Circumstances, which it is wholly foreign to this work to
relate, interrupted the continuance of the research. The facts
already related have come to my knowledge at too late a
period to allow of my pursuing the investigation; but I
trust, it will not long continue neglected.
DISSERTATIO PHYSIOLOGICA
INAUGURALIS
DE ABSORBENDI FUNCTIONE;
QUA3I EX AUCTORITATE
ORNATI VIRI, D. GEORGH BAIRD,
ACADEMIAB EDINBURGENAE PRAEFECTI;
NECNON
AMPLISSIMI SENATUS ACADEMICI CONSENSU ,
ET NOBILISSIMAE FACULTATIS MEDICAE DECRETO;
PRO GRADU DOCTORIS,
SUMMISQUE IN MEDICINA HONORIBUS AC PRIVILEGIIS
RITE ET LEGITIME CONSEQUENDIS;
ERUDITOIUJM EXAMINI SUBJICIT
THOMAS HODGKIN,
ANGLUS,
SOCIETATIS REGIAE MEDICAE EDINENSIS, ET PHYSICAE GUYENSIS SOCIUS.
" To 8k OTTwg lykvtTO toiovtov, lav £7rix£ip'h<Tt]Q %t)TEiv dvai(jBr]Tog, 0gj-
paSqay ko.it fjg <rrjg cMT&tvtiag, ical rijg Aij[iiovpyov dwdfietog." — Galenus.
Die i. Mensis viii. (Kal. Aug.) hora locoque solitis.
V1R0 OPTIMO
ALEXANDRO HUMBOLDT,
Philosopho, qui eximiis ingenii dotibus et omnigena scientia instructus, magnam
Americae partem obiit, ubi quaecunque proponit natura in illo magnifico
suo theatro contemplatus est, diversarum gentium mores, urbesque cognovit,
antiquorum incolarum fugaces ac perituras historiae reliquias indaga-
vit, collegit, oblivioni eripuit, et quodcunque dignum memoria sibi visum
est, aere perennioribus scriptis mandavit ; ita ut iis, qui peregrinari velint,
exemplar imitatione dignum, in omne aevum posuerit; illi praestanti
viro, qui, dum scientiae fines assidue ampliaret, inter omnia, nil humani
a se esse alienum, nunquam non putabat ; propter meam singularem in eum
observantiam, atque in testimonium animi memoris beneficiorum, quae mibi
indulsit, cum Lutetiae Parisiorum studiis incumberem, opusculum hoc offero
atque dico. O utinam pro ipsius mentis digniora possem referre !
THOMAS HODGKIN.
PRAECEPTORI spectatissimo
ANDREAE DUNCAN, Jun. M.D. R.S.E.S.
Collegii Medicorum Edinensis Praesidi, materiarum medicinalium, itemque me-
dicinae clinices, hac in academia professori, &c. Qui cum scientiam praelec-
tionibus promovet, turn insigni exemplo industriam, liberalitatem, et candorem
commendat et illustrat ; ob paternam solicitudinem, qua me, dum scarlatina
laborabam, curavit, et propter fructus et commoda nunquam obliviscenda ex
ipsius disciplinis percepta, cum in hujus urbis valetudinario sub illo clinicis
officiis et munere fungerer, hoc tentamen, pignus exiguum, animi non ingrati
defero, et honoris amicitiaeque causa illius nomine inscribo.
T.H.
PATRI SUO
THOMAS HODGKIN, S.P.D.
Officio sane deessem, si iniEscuLAPii aedem ingrediens, mei amoris et ob-
servantiae erga te, cui tot et tanta debeo, notam non ponerem.
Me prohibet, ilia tua modestia, ne nunquam obliviscenda tua in me officia ac
merita, enumerare suscipiam. Lector, cui forsan, hauds ecus ac mihi, optimo patre
uti concessum est, mente finget, ea quae verbis exprimere non possum. Plura
igitur non addam.
Licebit tamen tibi precari, ut diu vivas, et ita pancratice valeas, ut si quid in
mea arte feliciter valeam, potius ex aliis scias, quam propria experientia sentias.
Edinburgi, Die'i. Mensis viii. (kal. aug.) mdcccxxiii.
DE
ABSORBENDI FUNCTIONE.
PROEMIUM.
Priusquam ad rem veniam, de qua in hoc tractatu dis-
serere institui, pauca praefari liceat mihi, ne quis hoc mihi
vitio vertat, vel ex una parte, quod rem chemice tractem,
vel ex altera, quod curiosissimas et minutissimas elemen-
torum e quibus constent corpora investigationes nimis neg-
ligam, et quod ipse perpauca et quidem rudia experimenta,
minime cum hodiernae chemiae subtilitate congruentia in-
stituerim.
Nequaquam profecto me fugit multos et quidem prae-
claros esse physiologos, qui vasorum absorbentium ac-
tionem, et cum ilia arctissime conjunctas functiones, ni-
mirum concoctionem, secretionem, et nutritionem, extra
chimiae provinciam esse, et omnino sub vitae solius ditione
positas esse contendant. Hanc opinionem Cel. Adelon,
de absorbendi functione scribens, iterum atque iteriim pro-
tulit, ut ex sequentibus excerptis abunde patebit. " Cette
action n'a en elle rien de chemique, comme nous l'avons
deja dit ; et en efFet il n'y a nuls rapports chemiques entre
la composition du chyme et celle du chyle ; de la connais-
sance chemique de Tun on ne peut conclure a. la formation
de l'autre."* Sic quoque in alio loco.
" L'action d'absorption n'est pas d'avantage une action
chemique, car il n'y a nul rapport chemique entre les ma-
teriaux des absorptions internes, et les fluides, lymphe, et
sang veineux, qui en sont les produits; de la composition
chemique des unes, on ne peut, a, l'aide des lois chemiques
generales, conclure a la formation des autres ; ces absorp-
* Dictionnaire de Medecine, vol. i. p. 133.
346 APPENDIX.
tions onl enfin pour resultat de creer des matieres organi-
sees, et la vie seule, comme on le sait, a cette puis-
sance."*
Hie vero supervacaneum foret plura excerpere, ut opi-
nionem omnibus cognitam existere demonstrem.
Ego autem huic sentential assentire nequeo. Quoniam
enim intimam corporum compositionem, rationem scilicet,
et proportionem, quibus minutissimae particulae, rerum
primordia, vel corpora prima Lucretii inter se junguntur,
mutatam esse manifestum est, et cum porro talium muta-
tionum, nisi sint in corporibus animantium peractae, inves-
tigationem chimia omnium pace sibi sumat, declarare non
dubito, etiam in vivo corpore has investigationes chemici
esse. — Et sane mihi videtur hanc meam sententiam non
leviter esse confirmatam, eo quod ex chemia ipsa praecipue
cognoscamus, istas fieri mutationes, quarum rationem dare,
ad chemiam non pertinere praedicatur.^ Nonne physiologi
in errore versantur, vel ex una. parte chimiam nimis reji-
ciendo, vel contra, varias mutationes, quae in vivis cor-
poribus perficiuntur, jam notis chimiae legibus, in cor-
poribus carentibus vita, agentibus, explicare conando ? Has
leges ad supra dictas functiones explicandas non valere,
lubentissime concede Haec autem impotentia probat
solummodo scientiam ad summum perfectionis suae non-
dum pervenisse. Quod si etiamnum calorici, et vis gal-
vanicae facultates ignorarentur, et phaenomena ex his pen-
dentia chimico cuivis obvia venirent, non modo rationem
dare non valeret, sed cognitas theorias oppugnari fate-
ret ur.
Nonne in pari pene difhcultate, quoad varias vitae func-
tiones, adhuc versamur? At, me judice, nondum satis
tali ratione physiologi vitae vires contemplati sunt. Pariter
ac innumeri sunt sinus et fretus
" Sub utroque mundi axe jacentes,"
adeo nive_ et gelu praeclusi, ut hucusque exploratorem
* Dictionnaire de Medecine, vol. i. p. 150.
t Quippe cum earum materiarum, quae variis animalium organis subjici-
untur, et quae in iis mutationem subeunt, elementa, antequam in corpus accipi-
untur vi ejus altractionis, quae a chemicis affinitas vocatur, inter se retineantur,
necesse est ut ad earn vim opprimendam validior alia, et chemicis facullatibus
pollens, in corpore insit, et praeterea, ciim prior saltern, et verisimillime altera
quoque vis constans sit, necesse est ut efiectus constaates sint, et cei tis legibus
obedientes.
APPENDIX. 347
quemque frustrati sint, quos geographus non ided extra
suam esse provinciam unquam protulit, licet incertae liniae
in chartis expressae mortalium impotentiam testentur,
donee Paerius et comites, illisque similes, quos
. . . ..." non Boreae finitimum latus
Duratae que solo nives
abigunt,"
forsit olira opprobrium tollant : sic neque nos ob confessas
difficultates ulli scientiae suum munus et officium surripia-
mus. Hae enim difficultates, aut improbo labori cedent,
aut illam Galeni sententiam huic tractatui praefixam
confirmabunt :
" To 8k oTrwg sytvero toiovtov, lav £7ri%fipij<7»}£ Z,r\Ttiv, ava'arBrjTog,
(pwpaBrjcry tcai rfjg aijg aaSevsiag, Kai rrjg Arjfiiovpyov SvvdjjiEug."
Restat modo ut paucis cbemiae fautores placem. Tan-
tum abest ut labores illorum, qui variarum corporis textu-
rarum, et humorum, qui in his texturis insunt, vel ab his
secernuntur, compositionem, cum in sanis, turn in vitiatis
corporibus minutissime examinirunt, parvi faciam, ut si
quid illorum gestis addere conarer ego mihimet arrogans
viderer. Inter illos enim numerandi sunt viri merito
celeberrimi Lavoisier, Wollaston, Fourcroy, Vau-
quelin, Proust, Marcet, Berzelius, Chevreul,
H. et J. Davy, Brande, Prout, permultique alii in-
genio et scientia praediti.
Veriim illorum experimenta quanquam maxime laudan-
da, et ad chimiae scientiam utilissima, physiologiae parum
profuisse negari non potest. Hoc autem, ni fallor, variis
causis attribuendum est. Si chimicus non adest, si in-
strumenta, et alia necessaria paranda sunt, tempus varias
mutationes ciet, ita ut novae materiae, a vita ornnino
alienae, reperiri possint; hujus modi quoque materias in
complicatis ipsius chimiae operationibus saepe formari
credendum est. Ad haec, cum etiam chemico cuivis peri-
tissimo, si subtilem investigationem inire velit, necesse sit
ut materiae examinandae copiam quandam in manibus ha-
beat, humores in tenuissimis vasis, in quibus tamen in-
explicabiles illae mutationes fieri creduntur, hoc modo
examinari non posse manifestum est. Docent praeterea
et ratio et experientia, varias corporis materias proportione
elementorum non esse constantes : Sunt denique et aliae
348 APPENDIX.
causae, quas hie proferre supervacaneum reor : Satis est
dicere, me jam prolatis argumentis inductum, illas minu-
tias praetermittere, et potius proprietates manifestas, et
constantes indagare maluisse. Sic enim existimabam ab-
sorbendi functionis leges melius esse investigandas. Quod
si ego forte ea duntaxat vestigia indicavi, quae alii se-
quentes vitae viam non palantes exquirere possint, sum
voti compos, meque permagno laboris praemio donatum
arbitror.
DE ABSORPTIONE.
Animalium corpora absorbendi facultate praedita esse,
adeo omnibus liquet, ut argumentis ad hoc probandum ne-
quaquam opus sit. Quis enim bestiam bene pastam, vires
et auctam molem acquirentem, contemplari potest, quin
Lucretii verbis exclamet
" Dissupat in corpus sese cibus omne animantum."
Si vero hanc facultatem accuratius inspicimus, earn esse
functionem insignem, cum multis aliis arctissime conjunc-
tam, atque nulli, momento inferiorem constabit. Non
tantum alimentis dat viam, qua in corpus intrare, idque
nutrire possint, sed quoque, et rebus alienis, quae nonun-
quam in densissimis structuris reperiri possunt ; ex hoc,
modo morbos, inducit, modo curanti medico, ad illos levan-
dos auxilium praebet. Haurit etiam ex ipso corpore, et
submovet eas particulas, quae aliquandiu in corpore man-
serunt, et vitae diutius prodesse non possunt.
Alioqui necesse esset ut animal, superpositis accumula-
tisque particulis, tanquam crystallus incresceret ; id quod
ipsa partium forma refutat. Ut mihi videtur, in variis
secretionibus absorptio baud parum agit, certe jam secretos
humores non nihil mutat.
A meo proposito alienum est, in hac dissertatione omnes
formas sub quibus absorbendi functio sese praebet separa-
tim tractare. Non enim libello, sed volumine opus esset.
Illas tamen breviter enumerare licebit, et. ordine quern
secutus est Adelon in excellente tractatu jam citato,
quanquam cum illo auctore non in omnibus ejus opinio-
nibus consentio, lubentissime utar.
Forma simplicissima hujus functionis in animalibus in-
APPENDIX. 349
ferioris ordinis, nee intestina, nee cavum in quod cibus ac-
cipiatur habentibus reperitur.* Haec enim animalia toto
corpore alimenta ex circumfluentibus aquis undique imbi-
bere videntur. Foetus quoque humanus, qui dura matu-
ritatem assequitur cum variis inferioribus animalibus non
inepte com para tur, hoc modo a nonnullis physiologis, quos
inter numerandus est Blainville, optimus ille professor,
in primis diebus nutriri dicitur.f In superioribus animali-
bus multiplex est ; sed variae formae in duas classes sic
distribui possunt. Ad primam classem pertinet omnis ab-
sorptio, quae constans, et ad sanguinis formationem, vel
ad nutritionem necessaria est. Hie igitur numerandae
sunt.
\mo. Absorptio qua, ab cibo et potionibus, quodcunque
nutrire potest abstrahitur. Haec in superiore parte tenuis
intestini, in homine saltern, observanda est. In aliis qui-
busdam animalibus, ut e. g. in equo, potiones ex crassiore
intestino majori quantitate absorbentur. Non desunt qui
cutem etiam hac facultate non omnino carere exrstiment.
Experimenta vero quae Seguin et alii instituerunt, hanc
opinionem refutant.
Attamen negari non potest, aqua ad corporis superficiem
admota, sitim levari posse, sed hujus effectus rationem
dare non difficile est.
2do. Absorptio qua, inter inspirandum, principium ad
vitam necessarium ex aere hauritur. At licet haec ab-
sorptio inter suos fautores Blainville et Adelon ha-
beat, nondum demonstrate esse videtur.
Experimentis a quibusdam chemicis, et presertim ab Opti-
mo viro Gvjlielmo Allen et socio Pepys institutis, aere
adeo nihil in pulmonibus amittere apparet, ut etiam aliquid
* Ob leneram texturam quorundam inferioium animalium, et ob defectum
coioris in eorum humoribus, vasa in talibus animalibus deesse, non facile de-
monstrari potest. Non diu abhinc, optimus vir G. Clift mihi hujusmodi ani-
malium exemplum ostendit, in quo magnum vas, quod non antea suspicatus est,
invenit.
t Nonnulli existimaverunt humores, etiam in vivis corporibus perfectorum
animalium, per varias texturas permeare. Tta visum est celeberrimo Boyle, et
Albinus, Meckel, et Haller, talem opinionem complexi sunt. Fordyce,
Cruickshank et pleiique nostris temporibus, istam notionem rejiciunt: Pro-
chaska tamen, humores varias structuras permeare contendit, et ad hujus sen-
tentiae confirmationem, experimenta a seipso, et a Parrot instituta adducit.
Haec autem mihi contradictionibus obnoxia videntur. Quaedam Magendie ex-
perimenta, et recentiora Doctoris Coindet, Prochaskae sententiae non nihil
favent.
350 APPENDIX.
accipere videantur. Nitrogenium enim immutatum expelli-
tur, et item oxygenii pars, at pars altera, cum carbonio
conjuncta, acidum carbonicum evadit. Videbatur etiam
clarissimis Davy, et Gay Lussac majorem acidi quanti-
tatem ex pulmonibus expelli, quam ex amisso oxygenio
formari potuerat. Haud tamen reticendum est non nihil
nitrogenii in quorundam exploratorum experimentis eva-
nuisse.
Iliud vero in pulmonibus fuisse absorptum minus certum
est.* Alii volunt cutem respirandi functionis esse parti-
cipem. Haec sententia quod ad homines, et ad alia su-
periora animalia spectat, plane rejicienda est, sed, ut testa-
tus est Edwards, physiologus inter nostri aevi subtilissi-
mos habendus, in ranis, et in his similibus bestialis, res ita
sese habere videtur. Quamvis in ambiguo sit, utrum res-
pirationis essentia in absorptione consistat, nee ne, lucu-
lenter patet ex investigationibus Professoris Meyer, et
aliorum, membranam mucosam bronchia munientem hu-
mores mirum in modum absorbere posse.-f Talis autem
absorptio ad hanc divisionem non pertinet, sed potius, vel
* Non omnino reticenda sunt, Thomae Edwards experimenta. Cum supra
narratis non concurrunt ; illi videbatur oxygenium aestivo tempore, ei nitroge-
nium hieme, in pulmonibus absorberi. Eatendum est respirandi functionem,
nondum satis fuisse exploratam.
t Goodwyn, Autenreith, Schloepfer, et discipuli scholae veterinariae
Lugduni, jam ostenderant, aquam aliosque humores, in asperam arteriam, illaesa
vita, injeci posse, cum Meyer hanc rem accuratius investigare suscepit. Hie
varias materias multo citius ex pulmonibus, quam etiam ex intestinis absorberi
invenit. Operae pretium foret hujus absorptionis usus investigare. Fateor me
de hac re nulla experimenta fecisse. Attamen suspicor earn constitutam fuisse,
ni mucus unquam in pulmonibus tanta copia accumuleter, ut cellulas impleat,
commercium sanguinem inter et aera impediat, et ita respirationem supprimat.
Non desunt experimenta, quae aera, qui inter inspirandum expellitur, majorem
vaporis copia m ex superiore parte asperae arteriae, ex faucibus, et ex ore, quam
ex toto pulmone accipere indicant, licet in hoc, multo ampliori quam in illis,
humidae superficii exponalur. Hoc etiam ob alias causas, milii explicatu diffi-
cile videtur. Haec autem absorptio in causa fortasse partim habenda est. Mul-
tum inter Physiologos disputatum est, de octavi nervorum paris functionibus,
itemque de eorum sectionis effectibus. Mihi sane verisimillima videtur C. B.
Brodie de his nervis sententia. Eos scilicet, pulmonibus, ut alii nervi aliis
partibus, sensum praebere, quo sanguinem nigrum in ipsis inesse percipi possit,
qua perceptione ad cerebrum dilata, phrenicos, intercostales aliosque nervos,
necessarias musculorum respirationi inservientium contractiones excitare docet.
Haec autem Theoria non omnino nova est. Egregius ille Physiologus, Robertus
Whytt, hujusmodi opinionem diu antea protulerat. Ipse quoque, nonnullis
meis familiaribus huic similem sententiam prius protuli, quam suam Brodie
vulgaverat. Non tamen hanc solam esse nervi pneumogastrici utilitatem arbi-
tror. In parte sequente hujus dissertationis effectum, quem nervi in absorbendi
APPENDIX. 351
inter absorptiones quae afficiunt secretos humores dum in
corpore manent, vel inter adventitias quae classem secun-
dam constituunt, recenseri debet.
3tio. Ea absorptio quae veteres et jam depravatas par-
ticulas, ut novis locum cedant, submovet. Haec functio a
variis physiologis, varia nomina accepit, sic a Joanne
Hunter, Interstitial Absorption vocabatur, a Bichat Ab-
sorption decomposante ou nutritive^ a Buisson, Absorption
Organique. De hac forma minime dubitatur. Non modo
partium forma, ut supra dictum est, indicatur, sed experi-
mento probatur. Sic testantur Duhamel et Hunter
animalium ossa, ex rubea. tinctorum devorata, colorem ru-
brum accipere, intermisso autem medicamento, coloratum
os serius ocius demoveri. Ad hoc accedunt plurimae mu-
tationes quae aetatis processu fiunt in corpore. Glandula
thymus, et aliae partes foetui peculiares, in adulto vix ac
ne vix quidem reperiri possunt. Maxilla in juvene lata et
valida, in sene niultum minuitur. In sene quoque ossa
calvariae saepe tenuantur, et, ut alii dicunt, cervix femoris
non nihil mutatur. In morbis aliquando inter novarum
particularum formationem, et veterum abstractionem con-
sueta ratio manifeste perturbatur, hide macies oritur, vel, si
ossa praecipue afficiuntur, et pars terrea insolita ratione
submovetur, mira sequitur mollities.
4:to. Ad quartam et ultimam primae classis divisionem
referenda est omnis absorptio, qua iterum in sanguinem
resorbetur qualiscunque secretus humor, cui nulla patet via
ex corpore exeundi. Cujus modi sunt halitus, qui mem-
branarum serosarum glabras superficies, et cellulosae mem-
branae interstitia assidue humectant, item humores oculi
et auris labyrinthi, synovia in articulis, in bursis mucosis,
et in thesis tendinum : et si quid in corpore thyriodio, in
capsulsis renalibus, aut glandulis lymphaticis formatur,
inter haec recensendum est. Ad hunc locum referre debe-
mus resorptionem in caeteros secretos humores agentem,
earn scilicet, qua fel ex vesicula. crassius evadit, qua urina
in vesica jam dudum retenta, minus aquosa est recentiore.
Agit ita quoque in ore, in oculo, in mamma, et in aliis par-
tibus, et, ni fallor, ea causa est cur stercora in crassiore in-
testino concreta, et interdum arida fiant.
functionem habeant, breviter indicare conatus smn, et hie conjecto octavi ner-
vorum paris sectionem efficere, ut humores in bronchiis seereti, non solita ratione
absorbeantur, uncle spiritus difficilis magna ex parte oriatur.
352 ATPENDIX.
In secunda classe enuraerandae sunt oranes absorptiones
quae, cum nee perpetuae sint, neque ad vitam necessarie,
adventitiae nominari possunt. Irao etiam ut perficiantur
necesse est, vel, ut quidpiam alienum, idemque haud escu-
lentum extet in corpore, vel, ut aliquid insolitura in eo
eveniat.
\mo. Quamvis ut supra dictum est, corpus per cutem
ali posse incredibile sit, non ideo sequitur, cutem nullo
pacto sorbere. Sed contra, acres quaedam materiae, prae-
sertim si eodem tempore perfricatur cutis, hac via, ut om-
nibus liquet, facillime in corpus intrant, nee dubitari potest,
quin quorundam morborum principia non aliter sese in
corpus insinuent.
2do. Nusquam sane, aut frequentius, aut manifestos
quam in membranis mucosis haec functio exercitur, ut
quotidianis exemplis, unicuique innotescit.
3tio. Denique absorptio ex omni corporis parte fieri po-
test, sive materies aliena in quavis textura inseritur, sive
in ipso corpore aliquid morbo generatur, aut naturalis hu-
mor errat, et insolitum locum invadit. Sic in morbo regio,
bilis a jecinore per totum corpus dissipata, decedente
morbo, rursus ab omni parte absorbetur.
HAEC FUNCTIO VETERIBUS NON
INCOGNITA.
Definita jam breviter absorbendi functione, consi-
derabimus paulisper quid ea. de re veteribus notum
fuerit.
Quamvis Graeci diligentius quam caeterae nationes me-
dicinam cognatasque scientias coluerint, ab illis tamen
rudis anatomia scientiarum in numero vix (ac ne vix
quidem) inserta est ; inde necessario manca, et erroribus
implicata Physiologia.
Antiquissimis nihilominus illorum medicis animalium
corpora variis modis absorbere non latebat, ut sequentibus
excerptis manifestum fiet.
Incipiam ab Hippocrate Coo, primo quidem ex om-
nibus memoria dignis : dicit ille medicinae pater. — " 'Sayictg
oXkoi icai ek KOiXiag /cat t^wSev' SfjAov r) atcr^rjaig wg
zkttvoov »ceu uairvoov o\ov to crw|ua," et in alio loco,
" "EX»c£t fxlv jap to awjia enro rwv fipwfxaTwv »cat ttotCov ig
tt)v KOi\ir\v — 17 bfxoir] iKfiag ti)v bpo'm]v dia tCov <j>\e[3u)i>."
APPENDIX. 353
Hie, et in sequentibus excerptis non tantum actionem, sed
instrumenta quoque indicat. " Kal yap al tyXtfieg, al Ik
Tr)g vrfdvog, koi rav Evrepwv, lig a t,vXXeyETai to, aiTia, teal
ra, iroTa, iireidav SeppavSr) ravra, zXkovgi to A£7rrorarov,
Kal to vypoTaTOv, to §e 7ra\vTaTov avriov KaTaXdireTai, Kal
yivsTai KOirpog, Iv toXctiv IvTipoiai Totcn icarw." Item " Eieri
OE Kal curb tTjq KoiXrig, (pXifieg, ava to aCjpa, irapiroXXai re
Kal iravTolai, St' a>v 17 Tpocpr) Iv tlo aojpaTL tjo^erat." Dubl-
tare non possumus quin Erasistratus vasa chylifera vi-
disset quum dixerit — " 'Ev yap rtjj SiaipHoSai to iTTiyaa-
Tpiov, apa TtJ WEpiTovauo, Kara, to pscrsvTspiov aprripiag iouv
£<TTi cracpejg, £7rt pev twv vtioSriAojv lpi(po)v} yaXaKTog
7rXf]p£ig."
Nee magis haec vasa Heeophilum, quanquam il-
loruni finem non intellexit latuisse videntur, ut sequentibus
Galen 1 verbis apparet. " HpioTov plv yap, iravTi ™
p.£<T£VT£pi(it) (f>Xej3ag tTroirjcev l^iag avaKupivag avTio, rrj
Sptipei Thiv Evrspwv, pr\ Trepaiovpivag elg to rj7rap' wg yap Kal
Hp6<piXog tXsyzv, tig aSfvwSij Tiva awpaTa TeXtvTOJcnv avTag
al (pXijdeg, tu>v aXXwv (nraawv kwl Tag irvXag avatyzpopi-
v(s)v. — Galen us quoque corpus absorbere docuit, et ab-
sorbendi functionem in quadam attractione consistere exis-
timavit. Cuti etiam hanc facultatem tribuit, dicit enim —
" f Qcnrep, eta rwv ug to cippa Trepaivopevtov GTopaTCJV, ek-
Kpivwcri pev £^a» irav oaov aTpuSeg ko.1 KairvCideg TrzpiTTwpa,
psTaXapfSavovcri Se tig eavrag, Ik tov Trpi£\ovTog rjfiag aepog,
oiijc oAryrjv polpav' koi tovt zgti to irpbg 'linroKpaTOvg
Xeyopevov log ekttvovv Kal ucnrvovv Igtiv oXov to <rw/xa." —
Arterias quidem illam aliquanto habere suspicavit " rATpbv
pev oiiv iyovaai, ko.1 irvsvpa Kal Xbtttov alpa, Kara Talg Siacr-
Tcureig e'Xksiv al apTr)p(ai, tov Kara r?)v KOiXiav Kal to, ivTepa
Trepia-)(op£vov \ypbv, rj oiios. 6X(og rj iravTairacn awzTnatrkiv-
Tai j3pa^u.#"
In saeculis ignorantiae quae postea secuta sunt medicina
et physiologia cum aliis scientiis communis ruinae parti-
cipes fuerunt. Harum reliquiae ab Arabibus conservatae,
potius quam excultae fuisse videntur. Solebant medici
Arabes ad cutem admotis medicamentis uti, cum vel
urinam, aut vomitum excitare, vel ventrem movere, vel su-
dores elicere vellent. Nee ita fecissent nisi cutem sorbere
existimassent. Illos tamen ad hanc medendi rationem
* In nostris diebus, opinio huic simillima, a Cl. Prochaska esse renovata
videtur. — Vid. cap. viii.
A A
354 APPENDIX.
iatralepticorum exemplo adductos fuisse verisimillimum
reor.
Reviviscentibus tandem scientiis, anatomia cultoribus
non caruit.
Anno mdlxiii Eustachius ductum thoracicum primus
invenit, sed nescius illins naturae, venam albam thoracis
nominavit. Anno mdcxxii Assellius, Italus, vasa chyli-
fera diu ante ab Herophilo et Erasistrato visa, sed
parum cognita, animadvertit. Hie vero vivis animalibus
dissectis, ista vasa acerrime scrutatus est, et eorum func-
tionem, cbyli scilicet absorptionem, sagacissime assecutus.
Ea tamen in homine oculis cernere, ut cupiebat, nunquam
ipsi datum est. Hoc autem contigit feliciori Veslingio,
qui etiam in ductum thoracicum vasa chylifera secutus est
primus. Post chylifera vasa ab Assellio deprehensa vi-
ginti octo circiter annis, lymphifera, Olaus Rudbeck
Suecus invenit. Cum illo tamen de hoc honore certant et
Jolivius Anglus, anatomicus peritissimus, Danusque
Bartholinus.
Post hos alii anatomici haec vasa scrutati sunt, et
eorum actionem conjectarunt. At tandem Gulielmus
Hunter, lymphifera et chylifera vasa non nisi unura esse
et integrum vasorum ordinem, per universum corpus ex-
tensum, et ubique absorbendi functione praeditum coui-
periit. Hujus egregii physiologi discipulis Heuson et
Cruickshank, horum vasorum in corpore humano dispo-
sitionis scientiam praecipue debemus. Heuson quoque
et J. Hunter haec vasa in avibus, in animalibus amphi-
biis, et in piscibus primi invenerunt, et exploraverunt, nisi
forsitan Bartholin us in pisce Diodonte, ex familia. Gym-
nodontium, Cuvieri, eorum vestigia prius aspexerit. Nee
tacendum est Alexandrum Monro secundum, qui tunc
temporis in hac urbe florebat, et anatomiam com parati vara
magno fructu excolebat Gulielmi Hunter et discipu-
lorum observationes, non multo post, iterasse. Quinetiam
cum illis de primae inventionis laude certavit, quam tamen
hac contentione, non adeptus fuisse videtur.
Dura haec de vasis chyliferis et lymphiferis agerentur,
insiones physiologi Harvey, H.etK. Boerhaave, Swam-
merdam, Haller et alii veterum opinionem de ab-
sorbendi facultate in venis insita, et ratione, et experimentis
probare susceperunt. Pioinde orta est veterum fautores
inter et sectatores G. Hunter notabilis controversia, de
qua etiamnum sub judice lis est.
APPENDIX. 355
Priusquam hanc controversiam ineamus, non omnino erit
inutile, organa, functioni a nobis investigandae subservientia
paulisper contemplari. Minime tamen meo proposito con-
venit ; nee res ipsa postulat, ut longam et completam de-
scriptionem anatomicam hie proferam.
Primo igitur de venis loquar. Haec vasa non aliter ac
arteriae, quas et numero, et capacitate longe superant, ex
duabus membranis constant, atque etiam ut aliis vasis,
sic et illis circumdatur involucrum ex membrana cellulosa.
Tunicae venosae, arteriosis sunt longe tenuiores, et distentu
faciliores, sed et eaedem validiores, ut testatus est Win-
tringham. Membrana interna tenuis, laevis, et glabra
omni circuities sanguinis apparatui, ut alii dicunt com-
munis est, at alii venis dextroque cordi esse peculiarem vo-
lunt. Externa, sive propria, ex fibris non circularibus, ut
in arteriis, sed potius in longum dispositis constare reputa-
tur, ita saltern visum est celeberrimo Bichat ; declarat
tamen Magendie se nunquam hanc dispositionem reperire
potuisse.
Non desunt qui et arteriis, et venis, tres membranas, et
vim muscularem tribuunt, at licet Hunter, Blumen-
bach, Richerand, Monro, alter, et tertius, et multi alii
ita docuerint, horum vasorum functio et compositio prohi-
bent, ne earn opinionem amplectar.
Veruntamen nee irritabilitate, nee sese contrahendi fa-
cultate, venae penitus carere videntur. Bichat enim, qui
venis istas facultates vix concedit, et miro quodam errore
resiliendi vim illis omnino denegat, venarum contractiones
se bis terve animadvertisse confitetur. Chaussier, Ma-
gendie, et Adelon, has facultates in venis inesse ne-
gant. Beclard autem, rectius, ut opinor, vim vitalem
sese contrahendi, neque vero magnam, venis concedit, non
tamen reticendum est venas cavas, ubi dextrae auriculae
committuntur, et ex ea, non nullas musculosas nbras ac-
cipere videntur, ibidem irritabilitate manifests, non carere.
Imo etiam decedente vita, in hac parte quae revera ulti-
mum moriens vocari potest, irritabilitas sese postremum
ostendit, et mirabiles contractiones perficiuntur, ut amicus
meus vir acutissimus R. Knox M.D. praecisis squalorum
thoracibus, saepius et iterum conspexit.
Haec vasa, vena portae et quibusdam aliis exceptis, val-
vulis ex membrana interiore constantibus muniuntur. Ubi
minores venae in majores sese effundunt, valvulae plerum-
que reperiri possunt, at in cursu vasorum nulla, certa ra-
a a 2
356 APPENDIX.
tione ponuntur. Hae valvulae interdum arctiores sunt
quam ut officio fungantur, id quod Bichat, venae disten-
tioni solummodo attribuit : longe autem verisimilius est, in
talibus exemplis confbrmationem esse peculiarem. Atque
haec vetus sententia a, Magendie et aliis hodie promulga-
tur. Extremae venae ea sunt tenuitate, ut vix (ac ne vix
quidem) illas persequi possimus. Illarum tamen investi-
gatio ad nostram rem maxime pertinet.
Docent, Soemmering et Peochaska extremas arterias
in quaque corporis textura peculiari ratione distribui, sed
quonam modo sanguis ex illis in venas transeat, videre non
datur.
Bichat hie posuit peculiarem vasorum ordinem, quam
systeme capillaire nominavit. At, me judice, ita innovando
adeo non bonam distinctionem fecit, ut potius duos, ad
minimum, vasorum ordines confudisse videatur.
Antiquiores Anatomici structuram specialem, arteriis et
venis in termed iam imaginati sunt. Verum ex quo tem-
pore Malpighi, Leeuwenhoek, Cowper, et Spal-
lanzani venas arteriis continuatas ostenderunt, atque
quotidianis fere experimentis venas ex arteriis injectas ma-
terias accipere demonstratum est ; haec opinio suos fautores
amisit. Ita sane quarundam venarum initia ostenduntur,
at nequaquam exinde sequitur, alias venas non aliter
orio-'mem ducere. Recentius autem Prochaska, structu-
ram vasis carentem existere strenue contendit, illius tamen
sententia non veterum opinionem omnino renovat, ab ilia
enim non nihil discrepat. Quinetiam Chaussier et
Adelon, structuram extremis vasis interpositam non reji-
ciunt, neque tamen jam confirmatam habent. Venae
quoque a variis internis superficiebus, et etiam a solidis
corporis texturis, ut e. g. a musculis, apertis osculis inci-
pere, a nonnullis reputantur, sic testatus est Kaaw Boer-
haave aquam, vel ceram per haemorrhoidales venas in-
jectam, in intestinorum cava exire. Narrat etiam Meckel
se venas in pelvi sitas, ceram aut a'erem in vesiculas semi-
nales, vel in vesicam injiciendo, sine partium laesione
implevisse. Et sic quoque Haller se gluten piscarium,
caeruleo colore tinctum, in pericardium et in cerebri ven-
triculos non semel impulisse testatur. Leiberkuhn ma-
teriam in venas injectam, ex intestinorum villis defluere
animadvertit. Vidit etiam a'era per venas immissum, mem-
branam cellulosam pervadere.
Magendie quoque haec confirmat, quibusdam experi-
APPENDIX. 357
mentis ad venas cordis spectantibus. Talibus autem in ex-
perimentis Cruickshank partium structuram laesam
fuisse existimavit. Item Fordyce, haec venarum ostiola
in vivo corpore existere posse non credidit. Quanquam
vero haec experimenta mihi non sic rejicienda videantur,
nostra, tamen refert recordari illius rwv 'EfnrEipticwv sen-
tentiae, nobis a Celso traditae, scilicet " non quicquam
esse stultius, quam quale quidque vivo homine est, tale
existimare esse moriente, imo jam mortuo." Multa enim
longe aliter in viva ac in mortua. structura se habent. Si
haec sententia confirmatione egeret, experimenta ab
Alexandro Humboldt viro omnigena scientia omato,
et a clarissimo Professore Beclard in cutem facta memo-
rare possem.
llle, microscopio tricenties et duodecies millies et qua-
dringenties formam augente, cutem externam exploravit,
sed nequaquam potuit poros detegere; hie eandem cutem
altae hydragyri columnae subjecit, metallum vero nullo
pacto exudavit. Ast in vivo homine, ut omnibus notum
est, sudor facile, et interdum magna copia cutem permeat.
Solus igitur vitae
Calor ille vias, et caeca relaxat
Spiramenta.
Sunt quoque et alia experimenta ad nostram rem quam
maxime spectantia, atque hanc sententiam abunde confir-
mantia. Joannes Hunter in pluribus tentaminibus
materias per venas in intestina impellere, et vice versa,
venas ab intestinis implere frustra conatus est. Mortuo
tamen animali, per venas meseraicas intestinum inflavit.
Aliae venarum origines ab Anatomicis enumerantur, ut
ex folliculis, ex glandulis, et ex structura quae erectile tissue
vocatur. Verum illas specialiter tractare minime hie opus
est. Venis igitur relictis, jam ad alterum vasorum ordinem,
vasorum scilicet absorbentium vulgo dictorum, pergamus.
Cum haec vasa contemplamur, quaedam illis cum venis
communia, quaedam autem propria videmus. Vasorum
absorbentium pellucidae tunicae, venosis tunicis tenuitate
praestant, quibus tamen firmitate non cedunt. Sicut
venae, ex duabus membranis constant, ut Nuck primus
demonstravit. Interior membrana venarum interiori con-
tinua, huic non dissimilis videtur, ac pariter valvulis ejus-
dem generis, sed multo frequentioribus, munitur, ex-
terior, secundum Cruickshank, Magendie, Sheldon,
358 APPENDIX.
Good lad, et alios fibrosa est. Hanc autem structuram
Bichat detegere non potuit. Haller, Cruickshank,
Monro, Goodlad, multique alii vim muscularem vasis
absorbendibus attribuunt.
Alii autem istam facultatem in illis existere omnino ne-
gant. Bichat nullas oculis percipiendas contractiones
ab illis effici credidit. Non tamen omnino negavit illas,
darti in more, posse sese contrahere. Permulti, quos inter
numerandus est, Cel. Blum en bach, licet vim muscu-
larem rejiciant, sese contrahendi facultatem in his vasis
insitam admittunt. Professores Tiedmann et Gmelin
ductum thoracicum ex a'eris contactu, vel ex affixo liga-
mento se contrahere saepe conspexerunt. Non dubito
quin hae contractiones sint ejusdem generis ac contrac-
tiones a Doctore Parry in detectis arteriis observatae,
quasque tonicitati (parce verbo) adscripsit.
Nihil, magis quam glandulae, per quas in quibusdam
corporis partibus transeunt, haec vasa ab omnibus aliis
distinguit.
Rarius, sed aliquando tamen, vasculum hujus ordinis
per totum suum cursum cum nulla, glandula, committi-
tur, id quod Hew son in lymphifero vase ex pollice pedis
proveniente, Cruickshank in lumbis, et Magendie in
equis observavit. Usque adhuc, harum glandularum struc-
tura, et usus non satis comperta sunt.
Notatu quoque dignum est, vasa absorbentia, etsi
magno in numero concurrant, nusquam ampla fieri. Ipse
etiam ductus thoracicus, inferiores ramulos capacitate saepe
non multo superat.
Pariter atque ostiola, quibus minores venae in majores
sese effundunt, valvulis muniuntur, sic etiam ubi haec
vasa cum venis se committunt, valvulae inveniuntur.
Dubitari non potest, quin in plerisque exemplis pars
maxima chyli et lymphae, per ductus thoracicos dextrum
et sinistrum, in venas subclavianas sese effundat. In
multis de anatomia libris hae solae terminationes descrjbun-
tur. Quinetiam Haller et Cruickshank alias non
existere contenderunt, et hanc sententiam participant
Lieutaud, Hewson, Portal et Soemmering. Haec
autem vasa prae aliis, quod ad distributionem attinet
variant, et multa ab aliis anatomicis exempla prolata sunt,
quae satis superque demonstrant vasa, quae absorbentia
dicuntur multimodis cum venis rubris conjungi.
Mascagni quoque, qui tales communicationes impug-
APPENDIX. 339
nat, eas tamen in mesenteric), etsi rar6, invenit. Meckel
saepe, in venas hydrargyrum injecit per vasa absorbentia.
Astley P. Cooper, Baronettus, eodein modo hydrar-
gyrum in venam portae impulit : idem quoque fecerunt
Rosen, Walericus, Lobstein, Lindner, et Tied-
mann, et Gmelin. Docet Magendie lympham ex si-
nistra capitis latere provenientem, non raro per ductum
proprium, in venam subclavianam transmitti.
Abernethy vasa lymphifera efferentia a glandulis in
venam prosecutus est. Vidi et ipse vas lymphiferum ex
pulmone ortum, cum vena, sine pari committi.
In equo meus amicus B. Clark receptaculum chyli sese
in venam quandam lumborum effundentem invenit.
Denique ductus thoracicus a Duverney, Astley
Cooper, Dupuytren, et Flandrtn in bestiis saepis-
sime ligatus est. Hoc experimento, plures necatae sunt,
aliae autem vitam conservaverunt, at in his, ut Dupuy-
tren demonstravit, aliae viae patebant, quibus lympha ad
cor usque pervenire posset.
Quod ad horum vasorum radices extremas attinet, nullo
pacto faciliores assecutu sunt, quam venarum origines.
Chylifera vasa, etiam ab Assellio, ex interna superfi-
cie intestinorum oriri existimata sunt. Bartholin us,
Nuck, Cowper, Senac, Bergerus et Ferrier, lym-
phifera arteriis esse continuata rati sunt. Malpighi vero
haec a folliculis tantummodo oriri voluit. Haller, G. et
J. Hunter, Cruickshank, Meckel, et plerique alii
physiologi vasa lymphifera ab omnibus internis superfi-
ciebus oriri docent. Professori autem Meckel cum his
superficiebus non tam facile, quam venae, communicare
videbantur, et experimenta, quae nuperiiis instituitRiBEs,
ad eandem opinionem ducunt. Incipiunt quoque ex
glandularum ductibus, ut e. g. ex ductibus fellis, ex tubulis
lactiferis, nee non viis urinariis. Ad hanc sententiam ac-
cedunt, Hambergerus, Ferrier, Haller, Cruick-
shank, Desgenettes, Soemmering, Beclard et alii.
Postremo ab omni corporis parte nascuntur, et Bartho-
lini sententia de communicatione arterias inter et ab-
sorbentia vasa, nonnullis experimentis confhmari vide-
tur.
Affirmant enim Haller et Cruickshank materies in
arterias injectas, in lymphifera penetrare, et cum illis con-
sentit Magendie.
At contra hujusraodi origines strenue contendit Monro
360 APPENDIX.
secundus. Beclard etiam se de his communicationibus
etiamnum dubitare confessus est. Cum venis quoque tales
communicationes, a Vieussenio olim creditas, Meckel,
et Ribes existere demonstrarunt.
In foetu, Cruickshank vasa lympbifera per venam
umbilicalem implevit.
Hae omnes origines ab effectu monstratae esse videntur,
at ipsa oscula ea sunt tenuitate, ut cerni non possint, nisi
forsan in felicioribus quibusdam exempiis chyliferorum va-
sorum initia, in villis intestinorum microscopic- percipi
possint, et hoc modo se ea vidisse affirmat Cruickshank.
Singuliis villis duodecim circiter horum vasorum radiculas,
patula ostia habentes et radiorum more in unum vas con-
vergentes adscribit. Bohlius quoque haec ostia vidisse fer-
tur. Quae scripsit Leiberkuhn de ampullis, ex quibus
chylifera vasa incipere credebat, ab omnibus rejiciuntur.
De lymphiferorum ostiolis plures conjecturae prolatae
sunt. Hunter ea erucae os, Haller autem et Richard
puncta lacrymalia referre imaginantur. Bichat existi-
mabat ea in variis structuris, modis peculiaribus incipere,
et nonnunquam a capillaribus vasis oriri. Docet Blain-
ville, egregius professor, haec vasa definitis ostiis ca-
rere, et potius gradatim, et inexplicabili transitione, ex
membrana, cellulosa origines habere.
Chaussier et Adelon, ut supra notavimus, struc-
turam extremis arteriis, venis, et lymphiferis vasis inter-
positam non rejiciunt.
Morbi quibus vasa absorbentia (dicta,) interdum labo-
rant, venarum afFectibus non sunt dissimiles. Utraque
vasa ad inflammationem magis quam arteriae, ad conver-
sionem in ossiam materiam minus sunt proclivia. Utraque
etiam sponte aliquando clauduntur. Ad haec, lympbi-
fera vasa non nunquam mirum in modum dilatata repe-
riuntur, quod vitium profecto, cum varicibus aliquatenus
comparan potest. Non igitur veteres omnino inepte, haec
vasa tanquam venarum genus habuisse opinor.
Quoniam omnis absorptio, omnium pene consensu aut
uni, aut alteri horum vasorum ordini, aut ambobus con-
junctis ordinibus tribuitur, absorbendi functionem melius
tractare non possum, quam utriusque ordinis officia pro-
pria considerando. Nunc itaque ad antea dictam contro-
versiam rcvertamur.
APPENDIX. 361
Argumenta et Auctoritates, quae suadent dbsorptionem fieri
per vasa chylifera at lymphifera.
Assellius hovum vasorum illustris inventor, chylum
per ilia absorbed demonstravit, longa. serie argumentorum
et experimentorum, quae in canibus, in felibus, in porcis
nee non in vaccis exenteratis vivis, et etiam in equo ita
inciso instituit.
Bartholinus venas chylum absorbere omnind negavit.
Nunquam sanguinem cum chylo commistum invenit, nul-
lum aditum admisit, quo ex intestinis in venas penetrare
posset. Narrat praeterea, probatum fuisse, ligatis venis
chylum non ide6 minus absorbed, at ligatis Assellti vasis
restitare chylum, nee ex ventriculo, neque ex intestinis
ulterius progredi.
Ruysch his vasis absorbendi facultatem tribuit; sed
venas illam participare credidit, imo etiam in animalibus
aetate provectis, banc functionem a venis solummodo per-
fici docuit.
Ingeniosus Morgan, cujus opera mechanicas theorias
nimis redolent, lymphifera vasa serum ex sanguine, ut in
corpore refrigeretur accipere, et postea iterum in venas
effundere putavit. Ea tamen, absorbendi quoque facultatem
habere docuit, ut,ex prima propositione libri ejus de re medi-
ca mechanica constat. " ]No sort of substances can pass
the lacteals, recipient lymphatics, or concoctive strainers,
but in the form of a fluid previously reduced to an exceed-
ing fine and imperceptible vapour," et iterum ; " and it
cannot be doubted but the absorbent vessels, or recipient
lymphatics, which are spread over all the surface of the skin,
are as fine, or rather much finer, than the other (the cu-
taneous emunctories) ; since otherwise the same unavoid-
able mischief must necessarily follow, and certain parts or
portions of matter would be received into the animal fluids,
that could never afterwards be evacuated, and which must
therefore occasion the most desperate and mortal obstruc-
tions.*
Gulielmus Hunter, ut supra dictum est, chylifera
et lymphifera vasa propria absorptionis organa esse, et non
* Vid. Philosophical Principles of Medicine, and The Mechauieal Practice of
Physic, by T.Morgan, M.D.
362 APPENDIX.
nisi unum et eundem vasorum ordinem constituere, primus
docuisse habetur, nisi forsan Thomas Morgan cum illode
hac laude disputare possit.
Lymphiferorum vasorum actionem conjectavit. \mo, Ob
similitudinem inter lymphifera vasa et chylifera, quae tunc
temporis chylum absorbere omnium pene consensu crede-
bantur. 2do, Ob symptomata, quae morbiferum virus in
corpus intrans plerumpue comitantur. 3tio, Theoriam
suam praecique confirmatam habuit experimentis a fratre
suo institutis.
Joannes Hunter procul dubio inter strenuissimos
hujus absorptionis fautores merito habendus est.
Praeciso canis ventre, duas portiones intestini, unam in
superiore parte, alteram in infenore, postquam iis conten-
tas materias submoverat, inter affixa ligamenta inclusit,
implevitque lacte, quod brevi per pellucida vasa permeare
conspexit.
Venae autem nee candidum humorem accipere, nee tur-
gescere videbantur. In superiorem partem ovis intestini,
tenue decoctum amyli, caeruleo colore tinctum injecit, et
chylifera vasa, quae antea, ob protractum jejunium lym-
pham tantum colore carentem continuerant, caeruleo hu-
more conspicua visa sunt.
Indicum autem in venarum sanguine detegere nequivit.
Dein, ut indigo in venis siqua pars ab illis absorberetur
facilius detegere posset, lac per arterias miseraicas adegit,
donee purum per venas rediit, minime tamen caeruleum
colorem accepit.
In aliam partem ejusdem ovis intestini lac injecit, et vasa
absorbentia tumuerunt, licet album colorem non acce-
perint.
Aliam partem pura aqua tepida implevit, sed nullo modo
effectum a Kaaw Boerhaave productum obtinere potuit.
Injecit etiam in asini intestinum, moschum in aqua, solu-
tum, et illius odorem in lympha agnovit. Sed cum medi-
camenti portio in peritoneum effusa fuisset, hoc experimen-
tum in dubium revocare licebit. Maxima cura. sanguinem
a vena, non contaminatum collegit : odore omnino carebat.
Alio tempore in pleuram, et in peritoneum injecit colora-
tam aquam, quam brevi tempore in lymphiferis vasis in-
venit.
Alexander Monro secundus postquam his vasis diu
operam dederat, sic suam sententiam expressit. "Tandem
mihi persuadebam vasa lymphatica valvulosa, per totum
APPENDIX. 363
corpus venarum absorbentium systema efficere, neque ab
arteriis, ut vulgo receptum est, emanare."
In hujus sententiae confirmationem citat. \mo, Phaeno-
mena, quae sese praebent in quibusdam morbis, qui post-
quam partem aliquam afFecere vasa absorbentia, et gland ulas
conglobatas ei continuatas invadunt. 2do, Experimenta
in cadaveribus injectione facta. 3tio, Facta et opiniones
ex pluribus auctoribus excerpta. E quibus, sequentia hie
proferre, mihi liceat. " Peyerus vir fide omnino dignus
lympham non nullis experimentis circa hepar flavescere
vidit, cui Fallopius et Kirkringius addunt, lympham
non tantum subflavam, sed etiam amaricantem in vase
lymphatic©, per summam fellis cystidem reptante, se repe-
risse.
" Quae itidem testantur Sylvius et Riverhorstius,
claro omnino documento per vasa lymphatica, bilem re-
sorberi."
Ille etiam clarissimus Helvetiorum physiologus inde-
fatigabilis Haller absorbendi functionem in his vasis
insitam admisit, et nobis sequens experimentum tradidit.
" In vivo animali, aut nuper mortuo, non solus ductus
thoracicus, qui vere de genere vasorum lymphaticorum est,
et perinde vasa lymphatica hepatis, ad oleum vitrioli fac-
tum contrahuntur, sed imprimis in animali, cui plena fue-
rant aut chylo, aut lympha, aut ceruleo liquore, quern
animalia absorbere coegi, sub ipsis intentis meis oculis
toties vidi haec, sive lymphatica vascula, sive lactea
evanescere."
Docent quoque Mascagni, Lister, Blumenbach,
et Richerand, absorptionem his vasis fieri. In hujus
opinionis confirmationem, exemplum citari potest, quod
nobis memorat Cruveilhier qui ipse aderat, cum Du-
puytren explorationem fecit ; hie chirurgus celeberrimus
corpus examinabat faeminae, quae mortua erat tumore in
superiore et interna parte femoris : pus ibi coactum est,
et membrana cellularis eo loco inflammatione fuerat cor-
repta.
Professor cutem summa cura dissecans membranam
cellulosam albidis lineis distinctam animadvertit ; hae
lineae pendebant ex vasis lymphiferis ex corrupto loco
provenientibus, et pure repletis ; gland ulae inguinales et
lymphifera vasa usque ad glandulos lumborum, eodem hu-
more distendebantur.
364 APPENDIX.
Dum praelectiones ab Astley P. Cooper pronunciatas
discipulus frequentarem, inter plurima pretiosa morborum
exempla, ab optimo preceptore conservata, specimen et
ipse vidi, in quo lymphifera vasa a teste Fungo Haematodi
correpto progredientia, et etiam ductus thoracicus albida,
et cerebrum referente materia, huic morbo peculiari im-
pleta sunt. Allard in opere de sede et natuia morborum
venas absorbere negat, sed multum tribuit vasculis lym-
phiferis in venas se effundentibus : et Mason Good qui
in Physiologico proemate ad Eccriticos morbos spectante
contra absorptionem venarum contendit, hujusmodi usus
est argumento, quod praecipue nititur experimentis Pro-
fessoris Meckel (vid. p. 30 et 32). Good praeterea in
auxilium vocat contra Magendii experimenta, lymphi-
fera vasa ad ipsas arterias et venas pertinentia.
Argumenta et Auctoritates, quae suadent absorptionem fieri
•per Venas.
Nequaquam necesse est hoc in loco ad veterum opinionem
de venarum absorbendi functione reverti. Jam satis multa
de hac re in superiore parte memoravimus. Incipiam igitur
ab eo tempore, quo Assellius, novis vasis intentis, in
duas partes scidit contrarios Physiologos.
Celeberrimus Harveius venas absorbere strenue con-
tendit ; per alia vasa id fieri negavit.
\mo, Propterea quod chylo duobus itineribus nequa-
quam opus esset. 2do, Quod Assellii vasa in pluribus
animalibus (ut ait) non existebant, eo enim tempore in
multis non fuerant inventa.
Swammerdam quanquam humorem album in vasis
chyliferis vidisset, humorem istum chylum fuisse negavit,
sed potius quendam succum peculiarem esse, ex glandulis
mesentericis provenientem, existimavit. Chylum vero
venis mesentericis absorbed credidit ; vidit enim san-
guinem in his aliquando striatum, et albis lineis per-
mistum.
Herman Boerhaave venas absorbere contendit, \mo,
quod sanguis in venis mesentericis sanguini in aliis venis
dissimilis esset, ita enim ille credebat. 2do, Quod venae
arteriis capacitate praestant.
APPENDIX. 365
Narrat Kaaw Boerhaave se vidisse puram aquam
tepidam in ventriculum immissam, a venis bibulis absor-
bed,— per venas gastricas majores, et venam portae de-
fluere, et tandem per jecur in venam cavam pervenire.
Qaum tamen chylum, vasis quaelactea dicuntur, absor-
bed fere omnes confiterentur, antiquae opinionis fautores,
venas tanquem absorbendi functionis tantummodo par-
ticipes, vindicare contenti sunt.
Sic celeberrimus Hallee, qui chylifera vasa, et humorem
per ea progredientem accurate descripsit, de Joannis
Hunter experimentis scribens, sic suam sententiam ex-
pressit. " Multum tribuo CI. viri experimentis, in quibus
candor cum industria conjungitur, sed contrarii alia nume-
rosa ar^umenta habemus, ut non possim a praeceptoris
(Boerhaavii) sententia recedere."
Docuit quoque Meckel materias venis nonnunquam
absorbed ; atque etiam Bichat, postquam varia argu-
menta perpenderat, venas ad absorptionem conferre valde
suspicatus est, quanquam tamen pro certo non habuit.
Recentiori tempore experimenta hanc opinionem suaden-
tia a. multis instituta sunt Physiologis, quorum inter pri-
mos notandi sunt Emmert et Flan drin. Investigationes
porro Professoris Halle, experimentis Joannis Hunter,
Halleri, et Doctoris Musgrave, quod ad absorptas
materias coloratas saltern attinet, adversantur. Chylum
enim arguunt rerum devoratarum colore non affici.
At profecto Magendius, naturae scrutator acerrimus,
turn venarum absorptionis defensor, turn Hunterorum
oppugnator strenuissimus habendus est. Iteravit enim
clarissimi viri experimenta, eventa tamen omnino diversa
obtinuit. Praeterea bestias infusum E,hei, Prussiatem
Potassae solutum, et alkohol sorbere coegit ; has autem
materias in ductu thoracico detegere non potuit, quan-
quam in sanguine, aut in urina manifeste adessent. Quin-
etiam decoctum nucis vomicae in ventriculum aut in rec-
tum canis, post ductum thoracicum ligatum, immissum,
nequaquam ideo tardius veneficos effectus edere, monstra-
vit. In alio tentamine intestini portionem inter ligamenta
inclusit, omnemque connexionem cum reliquo corpore,
nisi per unam arteriam, unamque venam, quibus etiam
membrana cellulosa maxima cura detracta erat, submovit.
Dein hanc intestini portionem nucis vomicae decocto im-
plevit. At neque in hoc experimento veneni effectus tar-
dati sunt : Experimentum huic mutatis vicibus respondens,
366 APPENDIX.
anno praeterito, in Academia Regia Gallica narratum
audivi. Physiologus, cujus nomen me fugit, intestini
portionem supra dicto modo praeparavit, et connexionem
cum reliquo corpore per vasculum chyliferum tantum re-
liquit: venenum deinde injectum, effectus peculiares non
edidit.
Denique Magendius, ne quis ad vasa absorbentia in
ipsis vasorum tunicis insita confugeret, crus cani praecidit,
ita ut membrum non nisi per arteriam, et venam cruralem
cum corpore connecteretur ; et haec etiam vasa divisit,
postquam pennarum fistulas ad conservandam connexionem
interposuerat, deinde upas, lethale venenum, subter pedis
cutem infixit, et bestia protinus emortua est. Ad haec,
cum celeberrimo chirurgo Dupuytren centum et quinqua-
ginta experimenta instituit, in quibus varios humores mem-
branis serosis subjecit, nunquam tamen hos humores lym-
phifera vasa ingredi conspexit. Ex his et aliis hujusmodi
experimentis concludit, \mo, Quanquam certum sit, chy-
lum vasis chyliferis absorberi, dubium tamen esse, num
quid praeterea ab illis absorbeatur ; 2do, Lymphifera vasa
absorbere posse, non esse demonstratum ; venas autem
hac facultate manifeste pollere. In alio loco veterem opi-
nionem renovat, lympham scilicet ex arteriis in vasa lym-
phifera effundi. Praeterea contra absorptionem per vasa
lymphifera hoc argumento usus est nempe haec vasa re-
periri non posse, in oculo, in aure interno, aut in cerebro,
in quibus absorptio nihilominus, aut manifeste exercetur,
aut optimo jure conjicitur. Experimenta Joannis Hun-
ter tanquam imperfecta et male instituta rejicit. Prae-
terea. quod Hunter in chyliferis vasis invenit, et lac esse
existimavit, Magendie potius chylum fuisse suspicatur.
Meyer quoque, olim Bernae Anatomiae Professor, multa
experimenta ad absorbendi functionem spectantia instituit.
In his investigationibus varias experiendas materias, per
asperam arteriam in pulmones plerumque injecit, quippe,
ut supra diximus, ex bronchiis, et pulmonum cellulis, citius
et copiosius, quam ex ulla corporis parte absorptio perfici-
tur. Hanc absorptionem per venas pulmonales fieri docet.
Materias enim injectas in sinistro corde primum invenit, et
ligamentum ductui thoracico affixum nequaquam absorp-
tionem impedivit. Materias hoc modo injectas in vasis
lymphiferis serius invenit. In his experimentis prussiate
et muriate potassae usus est, quae non tantum in sanguine,
in urina, et in aliis secretis humoribus, sed etiam in qui-
APPENDIX. 367
busdam concretis corporis structuris detegere potuit. Ex-
perimenta quae instituit Ev. Home, dum vias, quibus
potiones ex ventriculo et intestinis evadunt, et lienis func-
tiones exploraret, absorbendi facultatem in venis insitam
demon strare videntur.
Hanc partem prius finire non possum, quam recentiores
labores Professorum Tied man n et Gmelim breviter me-
moraverim. Quod si illorum experimenta enumerare sus-
ciperem, hoc opus certe nimis fieret prolixum. Sufficiet
igiturconsequentias, quas ex illis inferunt enunciare. \mo,
Materiae colorantes veluti rheum, indicum, rubia tinctorum,
coccinella, cambogia et similia, in chyliferis vasis non re-
perienda sunt. 2do, Materiae odorantes tanquam cam-
phora, moschus, alkohol, oleum essentiale terebinthinae,
oleum empyreumaticum animale, gummi assafoetida, et
allii sativi radix aeque ac res colorantes chylum non affi-
ciunt. 'Stio, Plerique sales non minus vias chyliferas effu-
giunt. Hujusmodi sunt acetas plumbi, hydrargyri acetas
et prussias, ferri murias, barytae murias, potassae prussias,
&g. Sulphas autem potassae in chylo inventum est. Et
devorato sulphate ferri, ferrum in chylo non omnino deesse
videbatur. Neque reticendum est plumbum et prussiatem
potassae, utrumque semel in chylo fuisse repertum. Haec
omnia, vel pleraque saltern, in venarum sanguine, in urina
etiam, et in quibusdam aliis excretis homoribus reperiri
possunt. Interdum quidem has materias in urina, repere-
runt ciim eas in sanguine detegere non potuerunt. Tale au-
tem phaenomenon diu antea a Doctoribus Wollaston et
Marcet observatum est.
Horum experimentorum, quae tanta. perspicuitate venas
absorbendi facultate pollere ostendunt, ea explicatio quam
Mason Good et alii proposuerunt, venas scilicet absorptas
materias ex nonnullis curtis lymphiferis vasis ad ductum
thoracicum non tendentibus accipere, mihi prorsus nuga-
toria videtur ; nam licet pars chyli talibus vasis in venas
manifeste effundatur, si venosum sanguinem supradictis
proprietatibus donare quiret, necesse esset ut istae proprie-
tates in chylo multo magis conspicuae forent, secundum illud
scholarum axioma, " Propter quod unumquodque est tale,
id ipsum est magis tale." At in chylo, raro aut nunquam
percipi possunt. Quod si responderetur, ea chylifera pecu-
liaria esse, ad res quasdam absorbendas constituta, et nun-
quam non in venas sese effundere, nihil aliud esset, ac
\oyofj.a\iav excitare ; concessum enim foret venarum radicu-
las materias absorbere.
368 APPENDIX.
Haec sunt praecipua argil menta quae in hac controversial
prolata sunt. Quum vero in hujusmodi quaestione factis
contraria facta a clarissimis viris confirmata, in utraque
parte reperiamus, veritatem ab utraque participari verisimil-
limum est. Itaque dubitare non possum quin multi cum
Chaussier et Adelon consentiant, et nee Joanni Hun-
ter venas nihil absorbere concedant, neque cum Ma gen-
die, Hunterianas opiniones de absorbendi functione inlym-
phiferisvasis insitarejiciant. Hie tamen quaestioproponenda
est.
Si natura duobus vasorum ordinibus absorbendi functio-
nem concessit, num haec vasa in varias materias aeque
agunt? Sin aliter, quasnam leges sequuntur, etquid his,
quidve illis absorberi debet? Experimenta supra narrata,
venas et lymphifera vasa in diversas, potius quam in easdem
materias agere, probare videntur.
In sequentibus paginis secunda quaestionis pars consi-
deranda est.
Quae proprietates materias ut Venis, et quae ut Lymphiferis
Vasis absorbeantur, aptas reddunt ?
Haec quaestio, ut opinor, nondum satis Physiologorum
studium in se convertit. Jamjam supra memoravirnus
Magendie nil rdsi chylum, seu cibi portionem ad nutri-
tionem aptam, chyliferis vasis absorberi, caeterasque res
cunctas, quae in corpus intrare possunt, venarum iter sequi
existiinare. Atque huic opinioni congruere videntur con-
sequentiae, quas ex suis experimentis Tiedmann et
Gmelin inferunt. Verum enimvero si res ita sese habere
conceditur, quod tamen etiamnum in dubium revocare
licet, quaestio jam proposita non ideo minus responsionem
flagitabit. Parum enim constat, cur aliquid, ob usum cui
post nonnullas mutationes inserviturum sit, ex officio istos
aditus aliis materiis negatos ingredi sinatur, nisi speciem
quandam, et naturam singularem, etiam in limine, prae se
ferat. Praeterea, quamobrem natura, id quod nutrire possit
a non nutiiente tanta. industria sejungeret, et paulo postea
in venis conjungeret, et cordis contractionibus apprime
inter se commisceret ?
Res profecto difficultatibus scatet, et non sine diffidentia.
APPENDIX. 369
meam opinionem propono : Scilicet acida, et quae inter
acida quodammodo referri possunt absorbed venis, alkalina
vero, et his cognata lymphiferis vasis esse commissa. Hanc
conjecturam in trimestri libello ad res medicas et chirurgi-
cas spectante, hac in urbe a Doctore Duncan juniore,
clarissimo Professore edito, jam olim breviter protuli, et
quanquam multa experimenta instituere necesse sit, prius-
quani pro certo haberi possit, tamen fortasse non omnino
indigna aestimabitur, quae hie paulo fusius tractetur. In-
cipiam ab argumentis, quae, ut opinor, res alkalinas chy-
liferis et lymphiferis vasis absorberi indicant.
Quanquam chylus pro ratione cibi multiim compositione
variet, ut bene demonstravit Marcet, chemici omnes,
licet aliter de eo inter se discrepantes ei certe facultates
alkalinas, tanquam uno ore, tribuerunt.
In hoc enim consentiunt Vauquelin, Marcet, Ber-
zelius, Brande, et alii. Experimenta Professorum
Tiedmann etGMELiN ad eandem coaclusionem spectant.
In plurimis exemplis vires alkalinas in chylo observaverunt,
nee aliter res sese habuit dum tota intestini canalis acidas
materias contineret. At forsan aliquis mihi objiciet, ea
experimenta esse vitiata, miris materiarum farraginibus,
quas infelices bestiae devorare coactae sunt. Talem quidem
conjecturam mihi in men tern venisse confiteor. Sequens
igitur experimentum institui. Cuniculum, qui paulo antea
rumicis acetosae folia, materiam certe nullis contradictioni-
bus obnoxiam, devoraverat, vivum incidi.
Chylifera vasa humore leviter albido, et lac valde dilutum
referente, atque manifestas proprietates alkalinas habente
implebantur. Semicoctae tamen materiae, quibus intestina
distendebantur, proprietates acidas non minus conspicuas
praebebant. Sapor etiam rumicis, et odor quoque ali-
quatenus manebant.
Lympham vero alkalinas facultates habere non tam bene
observatum est. Brande declarat illam nee ut alkali,
neque ut acidum agere. Tiedmann autem et Gmelin
alkalinas proprietates uno quidem experimento notave-
runt.
Ipse quoque in ovibus nuperrime occisis exploravi lym-
pham, cujus contactu rocellam acidis rubefactum, caeru-
leum colorem accipere vidi. Neminem latet vasa absorben-
tia conspicua fieri glandulasque affici, in illis qui variolae
succumbunt. Humorem itaque ex variolarum pustulis
examinavi, et alkali facillime agnovi. Item in quodam
B B
370
APPENDIX.
homine, cui vesicatorium pectori ulcus induxerat, ex quo
glandulae axillares doluerunt et tumefactae sunt, lympha,
qua ulcus madefactum est, fuit manifeste alkalina. Prae-
terea gland ularum tumor et dolor, subacids, lotione ulceri
admota, cito levati sunt. Non tamen hide opinor, glandu-
las ab alkali fuisse exasperatas, sed potius virus in eo
solutum aptius fuisse factum ut vasis lymphiferis absorbe-
retur.
Magendie contra absorptionem per lymphifera vasa
objicit, gland ulas interdum, punctiuncula, nova et incon-
taminata acu facta, tumescere. Hoc vero mihi nuga-
torium videtur, ipsa enim inflammatio a vulnere orta ma-
teriam gignit, quae absorpta glandulas afficit, et parum
dubito quin ea, sicut permultae aliae materiae in corpore
productae, proprietates alkalinas habeat.
Mea, theoria de lymphiferorum vasorum actione admissa,
experimenta quae magno effectu contra horum vasorum
absorbendi facultatem Mag en die protulit, facile ita ex-
plicantur, ut magna, ex parte vim amittant. Strichnia,
picrotoxia, brucia, et alia principia vegetabilium veneno-
rum, licet quibusdam alkalinis proprietatibus polleant,
pene insolubilia sunt, itaque, ut docet Orfila, parum
agunt nisi cum acidis conjuncta. Quinetiam in veneficis
istis medicamentis cum acido superante existunt, et inde,
ni fallor, idonea fiunt quae venis absorbeantur. Barytas
fortasse est solum venenum alkalinum in aqua, dissolubile,
experimentis vero nequaquam idonea videtur, \mo, Quod
neque haec valde dissolubilis est. 2do, Quod propter
vehementes attractiones chemicas, cum aliis rebus protinus
conjungitur, et novas proprietates acquirit. 3tio, Quod
cum antea dictis venenis comparari non potest, quia licet
genus nervosum manifeste afficiat, tamen inter acria et
caustica venena potius quam torpefacientia recensenda est,
et ubi partes erosae sunt, contradicendi occasio deesse non
potest. In processu quo chymus format ur, materiae colo-
rantes separantur, ut bene demonstravit Magendie; ita-
que non miror eas in chylo non fuisse inventas, praesertim
si, tanquam indicum, in acidis potius quam alkalinis hu-
moribus solvendae sunt.
Bilis autem, humor natura, flavus et idem alkalinus, ut
supra diximus, vasis lymphiferis absorbetur, quod porrd
confirmant Soemmering et Desgenettes.
Nonne ex lymphiferorum vasorum actione, quam nunc
propono, pendet ea strumae curatio a Brandish et aliis
APPENDIX. 3~1
laudata, in qua potassa pura, caeteraeque praeparationes
alkalinae usurpantur. Quidam sales medii cum lymphi-
feris vasis, turn venis absorberi posse videntur; hujusmodi
sunt muiias sodae, sulphas potassae, etc. : in multis aliis
res non ita se habet. Operae pretium foret de his salibus
investigationera specialem iriire. Non oblitus sum Hal-
lerum acidas proprietates chylo tribuisse; dicit enim :
" Utilitas chyli proxima est, putrescibilem naturam san-
guinis, acido succo suppeditato, contemperare." At cum
ipse confiteatur chylum nullo rubore succum heliotropii
tingere, et ad pinguitudinem acorem obvolventem confugere
cogatur, CI. viri opinio hac in re nullam vim habet. Pa-
rum dubito quin a nonnullisphysiologis multa meae opinioni
objiciantur : quaedam tamen dicenda sunt, quae forsitan
nonnullas contradictiones avertent. Nondum nervorum
actionem cum absorbentium vasorum functionibus con-
junctam, physiologi satis exploraverunt. Ex hac tamen
conjunctione, chemicae mutationes vitae peculiares magna
ex parte pendent. Sequentes notationes ab hac re non om-
nino alienae sunt. Anno proximo elapso, lympham in equo
ad feras in horto regio Parisiensi alendas occiso examinavi.
Contra expectationem hanc lympham acidam esse inveni.
Non leviter attonitus, mihimet ipse exclamavi ; actum est
de theoria mea. Rem tamen in animo perpendens, hanc
exceptionem tempori, quod inter equi necem, et lymphae
tentamentum elapsum erat, attribui. Crassum intestinum
aqua, cum concocto foeno commista, et ex eo colore sub-
viride fusco tincta, plenum erat. Vasa lymphiferaex hac
parte intestini progredientia, humorem acidum, ut supra
dixi, continebant, qui, licet translucidus, et multo dilu-
tior, ab humore in intestino, colore non valde difFerebat.
Strenuus Hunteri fautor hie sine dubio diceret, lym-
pham ex intestino colorem accepisse. Hoc tamen, licet
probabile, ego non assero. Hac notione de mutata. post
mortem actione perculsus, experimenta Joan n is Hun-
ter accuratius examinavi, et fateor me cum opinione
Magendie de celeberrimo illo viro consentire non posse.
Hunterum enim etiam ex istis illius experimentis, quae
ad absorbendi functionem pertinent, peritissimum, eun-
demque vitae parcissimum existimandum duco. Luben-
tissime concedo Hunterum absorbendi functionis scien-
tiam imperfectam liquisse. Si ille omnia fecisset, Ma-
gendie gloria minor fuisset. Quis autem imperitus,
inciso animalis abdomine, vita perstante, octo difficilia ex-
b b2
372 APPENDIX.
experimenta instituere potuisset ? et quis nisi vitae parcus
fuisset, non potius octo animalia ita incidisset ? In primo
experimento nervi ligati fuisse videntur. Itaque haud
miror lac fuisse absorptum, quia, ut in mortuo animali,
actio nervorum defuit. Magendie humorem in chyliferis
vasis repertum chylum fuisse contendit. At nequaquam
dubito quin physiologus ille sapiens ab hac opinione de-
cedat, cum consideraverit. \mo, Lac nee humori gastrico,
neque pancreatico fuisse subjectum, neque cum bile com-
mistum. 2do, Lacinjectum fuisse in earn partem inferiorem
intestini, in qua, ut testatus est Hunter, chylus deerat.
In alio animali nervi fuisse intacti videntur, et, ut Hun-
terus ipse agnovit, lacteus humor in lymphifera vasa non
penetravit licet lac in intestinum injectum esset. Indicum,
aeque ac lac, ligatis nervis absorptum fuisse videtur.
Halleri et quorundam aliorum physiologorum experi-
menta non adeo enucleate narrantur, ut dici possit utrum
meae opinioni faveant, an repugnent. Unum nihilominus
inter ProfessorumTiEDMANN et Gmeltn experimenta, hie
non reticendum est.
Acetas plumbi et tinctura rhei cani data sunt et, occisa
bestia, rheum, quod fieri non solet, in chylo repertum est,
plumbum quoque in chylo aderat. Praeterea hie humor
aut medius (neutral) aut etiam acidus videbatur, quia ne-
cesse fuit alkali addere ut rheum conspicuum fieret. Ex
quo conjicio plumbum, quod paralysin inducere solet, in
nervos agere, et absorbendi funcionem perturbare posse.
Chylus alkali carens hujus plumbi effectus optimum indi-
cium videtur; nam ubi ob minorem plumbi quantitatem
hie effectus non productus est, et materiae colorantes non
absorptae sunt, chylus solita ratione alkalinas proprietates
habuit. Non possum non credere, discrepantiam, quam
supra inter quosdam egregios Physiologos existere notavi,
ex hac mutata vasorum absorbentium actione praecipue
pendere.
Modo paulisper venas inspiciamus, et consideremus
quantum in hac parte conjectura mea factis nitatur. Quod
si vasorum, quae absorbentia nuncupantur, actio obscura
est, et explicatu difficilis, multo venarum difficilior. Cum
venarum officium evidentissimum sit, sanguinem, jam ad
extremas arterias perventum, non nihil mutatum ad cor
reportare, necesse est ut minus evidentis officii, absorbendi
scilicet, effectus difficilius assequamur, et necessario sim-
plices nunquam contemplari possimus. Praeterea, licet
APPENDIX. 373
permulti sanguini operam dederint, discrimen sanguinem
arteriosum inter et venosum nondum satis prolatum est.
Admissa theoriae meae parte priore, ad vasa lymphifera
spectante, haec secunda ratione quodammodo indicari
videtur. Nam si lymphifera vasa partes alkalinas ab-
sorbent, etiam si chymus medius antea fuerat, et a for-
tiori si acidus, necesse est ut reliquum acidum fiat. At
magna pars hujus, quodcunque sit, reliqui, venis absor-
bed videtur*, et intestini fmern versus acor plerumque
deest.
Haec autem ratiocinatio, factorum confimatione non
omnino caret. Anthonius Todd Tompson, dum acidi
oxalici in cuniculos effectus exploraret, acidum in san-
guine venoso invenit. Hoc quoque ab amico meoLuDOvico
Perey saepe observatum est. Non modo charta Lichene
Rocella tincta rubefacta est, sed sanguis mirabiliter nigruit.
Et licet recentiora experimenta a Doctoribus Coindet et
Christison instituta, cum supra dictis non omnino con-
sentiant, meae tamen theoriae non ad versantur; his enim
exploratoribus acidum per absorptionem agere videbatur,
et quanquam acidas proprietates in venoso sanguine detegi
posse negent, mutationem sanguinis coloris effectam, ab
acidi contactu procul dubio provenientem confirmant. Quae
de acidorum mutatione scripsit ingeniosus Coindet, non-
dum legendi occasio mihi data est.
Res profecto quae maxima cura exploretur dignissima
est, chymica enim est actio, cujus leges prolatae, etiam si
causa in aeternum lateat, physiologiam necessario pro-
movebunt.
Acidum nitromuriaticum, aeque ac oxalicum in corpore
mutari videtur. Doctor Combe, cujus dissertatio de acido
nitro muriatico, Regiae Societatis medicae palma. donata
est, acidum in sanguine nequaquam reperire potuit. In
bestiis vero, hoc acido non aliter ac oxalico necatis, san^
guis venosus niger est, at in sinistro corde majore etiam
quam solita ratione rubet. Physiologi multum inter se de
natura. sanguinis venae portae discrepaverunt. Alii enim
hunc sanguinem non solita ratione coire declaraverunt :
hoc autem ab aliis negatur. Mihi persuasum est hanc dis-
* Reliquum strictissima diclione non bonum esse verbumconfiteor, quippe cum
venae eodem tempore, quo lymphifera vasa agant, sensus autem satis evidens
est.
374 APPENDIX.
crepantiam, potius ex quadam varietate a materiis ab-
sorptis proveniente, quarn ex scriptorum fide proficisci.
At bene cognitum est acida parva quantitate cum san-
guine commista illius coitum impedire posse. Nonduui
novimus quomodo sanguis arteriosus in venosum mutetur,
neque statum carbonii quod in hoc, majore quantitate
existit. Argumenta vero non desunt, quae illud etiam in
venis, tanquam acidum iramaturum existere indicent,
Hoc autem admodura dubium est. De principio colorante
in rhei radice existente, haud multum novimus ; notatu
tamen dignum est, hoc principium, quod ex experimentis
Everardi Home, et Professorum Tiedmann et Gme-
lin venis absorbed videtur, alkalinum contactum exigere,
quo in sero sanguinis manifestum fiat. Indicium, meo
quidem judicio, alkalinum sanguini naturale ab aliquo
acido superatum fuisse. Indicum praeterea, quod acidis
praecipue solvitur, venis manifeste absorbetur, etsi color
postea, alkalino in sanguine existente mutatur. Ad haec,
cum oleum, fixum, ut vocatur, et alkalinis consentaneum,
chyliferis vasis absorbeatur, quod cremore chylo supernante
ostenditur, essentialia contra, et empyreumatica, non mi-
nus acidis convenientia, venis absorbentur. Si venae ma-
terias acidas accipiunt, nonne hoc in causa, est, cur sitientes
acidulos humores appetant? Venae cum ob majorem ca-
pacitatem, turn ob faciliorem cum intestinis communica-
tionem citius et copiosius quam chylifera vasa, humores
imbibunt : Sapiens itaque natura venis aptissimae potionis
desiderium sitientibus excitasse videtur.
Alkohol magna quantitate et omnino sine mutatione
venis absorbetur. Fateor me nondum conjectare potuisse,
quamobrem his vasis accipiatur, et illis rejiciatur. Ab
acido tamen acetico, compositione non longe distat.
Priusquam commoda, quae ex absorptione modo supra
conjecto perfecta, oriri possunt, et quantum haec conjec-
tura cum phaenomenis in variis functionibus apparentibus
conveniat, consideremus, abs re non erit, paulisper exami-
nare quid physiologis visum fuerit, de modo, quo variae
absorptae materiae, sive in vasa chylifera, sive in venas
accipiuntur.
Nonnulli existimavere pressuram intestinorum super ea
quae in illis continentur, liquidas chimi partes in patula
vasorum ostea adigere. Plures vero, quos inter numerandi
sunt Haller et Monro secundus et tertius, materias
primo per attractionem vasorum capillarium sorberi, et
APPENDIX. 375
postea vasorum contractionibus, valvulis adjuvantibus,
promoveri.
Mag en die quoque, licet in opere suo de Physiologia
ignorantiam de hac re confessus sit, tamen in dissertatione
quam recentius Academiae Regiae Parisiensi subjecit, istam
attractionem, tanquam absorptionis causam, adniisisse vi-
detur. Quod si absorptio, in tali actione constaret, turn
sane necesse foret, omnes humores, sine discriraine in vas-
cula utriusque ordinis intrare. Ad hanc difficultatem vitan-
dam, B i chat sensum, et vim contractionis organicae, ut
ea nominavit, finxit.
At praeterea quod illas proprietates sensibus nostris
nequaquam assequi possumus, theoria variis contradic-
tionibus est obnoxia : Haud quaquam necessarium est hie
referre omnes difficultates de quibus alii physiologi men-
tionern fecerunt ; sequens mihi insuperabilis videtur. Cum
illarum facultatum, quas imaginatus est Bich at, actio tota
foret in rebus quibusdam accipiendis, aliisque rejiciendis,
patet eas, si existerent, mechanicam tantummodo separa-
tionem esse perfecturas. Ea autem elementa, quae inter
se chymica attractione retinentur necessario sine mutatione
manerent.
BRUGMANsin auxilium vocat vitam propriam in absor-
bentibus vasis insitam; et clarus Blum en bach, ni fallor,
cum illo quodammodo consentit. At ita profecto difficultas
nequaquam explicatur. Quidam inter celeberrimos nostri
aevi philosophos et physiologos, Young nimirum, et Wol-
laston et Wilson Phillip et Prochaska in hujusmo-
di vitalibus actionibus, vim galvanicam multum perticere
existimant. Verum enimvero si a tantis viris decedere sit
juveni permissum, ego quidem fateor multas difficultates
obstare, quo minus talem opinionem amplectar. Mihi
quoque praematurum videtur causam mutationum chimi-
carum, quae in vivis corporibus perficiuntur, imaginari,
priusquam phaenomena ipsa, et leges quibus parent, melius
cognoscanlur. His autem inventis, sed non antea, ex-
quirere licebit, num vis, unde proveniunt, galvanicae,
aut alius jam notae vis modus tantiim sit, an potius novum
prorsus principium.
Multum a physiologis inquisitum est, quomodo partes
concretae absorbeantur. Hunter, ut supra notavimus,
extrema resorbentia vasa, tanquam erucae, rodere con-
jectavit. Notavit Bich at, absorptionem cum corpusculis
agere, et difficultatem de submovendis partibus concretis,
376
APPEN D1X.
omnino esse imaginariam. Haec sententia tarn vere de
multis aliis rautationibus quam de absorptione proferri
potest. Penitus itaque absurd um videtur, easdem visibiles
particulas in sanguine, in variis corporis texturis, et in
multis secretis humoribus, imo etiam in coctis carnibus
exquirere.
Vanae itaque aestimandae sunt plures microscopicae
investigationes, ab Everardo Home, et Bauer institu-
tae, " quoniam" ut ait Lucretius
" —. Extremum cujusque cacumen
' ' Corporis est aliquid nostri, quod cernere sensus
" Jam nequiemnt."
Constat experimentis Mayer et Magendie varias ma-
terias a matre in foetum per absorptionem transire : de hac
autem absorptione nihil dicendum habeo.
Vegetabilia non minus quam animalia absorbendi func-
tione fruuntur, illis autem non aeque achis, operam dedi ;
licebit tamen, sequens experimentum proferre. In figlino,
lauto sabulo impleto, gramina varia, fabas, pisa, atque alia
semina consertii ; totum deinde haud tenui infuso croci
madefactum, in locum obscurum seposui, ne color ullus in
plantis ipsis generaretur, et subinde irrigationem cum su-
pradicto infuso repetivi. Germina brevi pullulare sed nequa-
quam croco tincta. Infusum tamen colorem magna ex parte
amisit, et odorem peculiarem acquisivit. Infusum autem,
in quo semina non aderant, vix, aut ne vix quidem, muta-
tum est. Parum dubito quin supra dictae mutationes
seminum cotyledonibus, utvocantur, et putaminibus partim
productae sint, multum tamen tribuo decompositioni ab
ipsa, germinatione provenienti. Ex hoc experimento conjicio
effectus, quos Desfontaines etalii obtinuerunt, ex vaso
rum sectione pependisse.
Nunc tandem, quantum meo proposito convenit, et for-
sitan amplius quam lectoris patientia condonabit, absor-
bendi functioned exposui. Restat modo pauca proferre de
quibusdam effectibus, qui, ut mihi videtur, ex absorptione
modo quo fieri suspicatus sum perfecta, provenire possunt.
APPENDIX. 377
DE QUIBUSDAM PHAENOMINIS CUM ABSOR-
BENDI FUNCTIONE UT SUPRA PROLATA EST
conjunct™ CONSIDERATTS.
Quoniam hanc dissertationem jamjam, insolita, ratione,
produxeriru, rerum duntaxat fastigia sequi licebit.
Quamvis haud necessarium sit plura dicere, de utilitate
duorum vasorum ordinum, ad varias materias a chymo se-
parandas, quippe cum lector ex superiore parte, meas de
hac re opiniones facillime concipere possit, non omnino
supervacaneum erit eorum utilitatem, in variis corporis
partibas examinare. Quaeri enim potest. Si hae partes
uno tantum vasorum ordine, arteriis scilicet, deponuntur,
quamobrem ad illas submovendas duobus opus est? Res-
pondeo : Corporis partes fere in hoc modo e-laborari suspi-
cor. Cum sanguis arteriosus ad extrema vasa pervenit,
cum venarum et lymphiferorum vasorum initiis committitur.
Haec enim vasa ubique in corpore adsunt.
Nunc si haec vasa diversas materias attrahunt, modo in
variis structuris diversa proportione concurrant, et tertia
substantia relicta varietates totidem exhibebit. Novae au-
tem particulae natura, partim pendet ex natura adjacen-
tium particularum, atque multum, ni fallor, ex composi-
tione particulae cui successura est, et quae cum reliquo
sanguine, vasis absorbentibus submovenda est. Errant
autem, qui tales corporis ruinas, in istis vasis exquirunt,
nam ut supra diximus, omnino decomponuntur. Praeterea,
licet veteres particulae, a novis quodammodo discrepent,
tamen cum inter se utraeque commutatae sunt, sanguis ad
cor rediens, postquam illas amisit, et his acceptis, venosus
evasit, eo usque reparatur, ut in omnibus texturis eandem
speciem habeat.
Multum a Physiologis disputatum est de secernendi
functionis natura. Alii existimavere secretos humores ex
sanguine minutis vasculis esse colatos. Alii multum motui
tribuunt, atque alii fermentationem in auxilium vocant.
Nonnulli dicunt secretionem ex peculiari vasorum actione
dependere. Hoc autem, rem nequaquam explicat : factum
tantummodo aliter exprimit. Vis galvanica, cui tantum
tribuitur a quibusdum claris viris, secretionis causa habe-
378 APPENDIX.
tur. Nuperrime chemicus ille celeberrimusTHENARD post-
quam deutoxydum hydrogenii, fibrina sine ulla mutatione
hujus materiae, decomponi posse invenerat, humores in cor-
poribus animalium, fibrina secernentium organorum de-
componi, et ita secernendi functionem explicari posse con-
jectavit. Ego vero suspicor, hanc functionem in actione
constare simillima actioni quam corporis partes elaborare
supra imaginatus sum.
De secernendi functione quaestio inter physiologos orta
est, quam omnino praetermittere nolo. Alii enim, quos
inter numerandus est Adelon omnes corporis partes, atque
omnes secretos humores ex arterioso sanguine formari do-
cent : Alii autem sano-uinem venosum ad bilem saltern for-
mandam conferre existimant. Jacobson vero, ex quibus-
dam observationibus in piscibus institutis, sanguinem ve-
nosum, multo majore functione fungi conjectat. Cum illo
quoque consentit Blainville, qui plurimos secretos hu-
mores, huic sanguini attribuit, et credit etiam vasa pam-
piniformia, et lien quoque, organa constituta fuisse, quae
sanguinis moram efficiant, qua. ad nonnullos secretos hu-
mores formandos aptior fiat. Licet hanc notionem non
amplectar, effectum peculiarem sanguinis venosi morae
esse attribuendum reor, formationem scilicet nigrae materiae
quod naturaliter in oculo, et in Ethiopis cute existit, et
pigmentum constat, et quod morbo, saepe in pulmonibus,
non raro in liene, et interdum in aliis partibus, ut in cute
hominum etiam a Caucasia stirpe generatorum existit.
Ecce argumenta quibus haec opinio nititur.
Primo ea exempla examinemus, quae nobis pathologia
profert, horum enim causae plerumque evidentiores sunt.
Materies nigra, quae in pulmonibus et in glandulis bron-
chialibus reperitur a Pearson, carbonio cum aere inspirato,
perperam tribuitur. In parva quantitate nullum incommo-
dum parit, et in adulto adeo vulgaris est, ut multis medicis
nequaquam morbida videatur ; interdum vero, magna quan-
titate existit, ut in iis qui in arctis urbium vicis habitant,
aut in profundis fodinis vitam degunt, at longe prae aliis in
iis qui phthisi laborant, aut alio quovis morbo, qui per Ion-
gum tempus functiones magnae pulmonum partis impedit.
At in omnibus his exemplis sanguis per pulmones, non so-
lita. ratione cursum habet, et imperfecta ab excessu carbonii
purgatur. Lien quoque in se multurn sanguinis venosi
APPENDIX. 379
habet, qui praeterea. tardo circuitui obnoxius est, praeser-
tim si mea de hoc organo conjectura admittitur.*
Si eorum exemplorum, in quibus cutis nigruit, historiam
investigabimus, hoc efFectum a repentino et opprimente ter-
rore ortum fuisse inveniemus. Sequens exemplum proferre
sufficiet. Inter horrores Gallici imperii eversionis, femina
capite damnata est, qua, sententia eo usque affecta est ut
cutis more supra dicto brevi nigruerit : remissa, vero paena,
ilia permultos annos vixit, et nigrum calorem, tempore ta-
men leviter minutum conservavit.
Post mortem cutis explorata est, et materies colorata in
rete mucoso reperta est, vel, ut diceret Blainville, super
rete vasculare verum pigmentum impositum est.
Nunc ad oculum respiciamus, in quo certe naturaliter, et
in sano statu nigra materies existit. Nonne venae contor-
tae sunt (unde etiam vasa vorticosa vocantur,) eo proposito,
ut sanguis moretur, et pigmentum deponat, quo lucis er-
rant.es. radii absorbeantur, et oculi globus opacus reddatur ?
Vidi ante paucos dies Heusingri recentem de pigmento
nigro dissertationem. Hie auctor quoque existimat mate-
riam nigram ob excessum carbonii formari, et eodem prin-
cipio tribuit oculi pigmentum, materiem nigram in pulmo-
nibus, et materiem colorantem capillorum, unguium et
pennarum. Nonne meae opinioni consentaneum est, ma-
* Vide Edinburgh Medical et Surgical Journal. In hoc libro, lien organum
esse proposui, quo graves effectus ex aucta copia fluidoruni, et ex diminuta capa-
citate vasorum prohibeantur. Tunc temporis nesciebam Doctorem Rush, Phi-
ladelphiensem, eandem sententiam emisisse, et Doctorem Bhgtjssais in praelec-
tionibussuis huic similem notionem proferre. Tiedmann et Gmelin volunt hoc
organum, vasis chyliferis et lymphiferis tanquam appendicem esse, in qua. lym-
pha coeundi facultatem, et subrubrum colorem adipiscitur. Hae autem proprie-
tates manifestae sunt in lympha quae nee lienis actioni subjecta est, ueque lym-
pham ex liene provenientem accepit. Credo equidem lympham has proprietates
in omnibus corporis partibus comparare posse, etsi in iis praecipue, quae in se
multum sanguinis habent. Non tamen reticendum est illos physiologos ad ex-
perimentum confugisse. Lienem canis execuerunt : bestia paucis diebus con-
valuit functiones parum turbatae sunt, modo paulo macrior quam antea videba-
tur. Post dies octodecem occisa est, et exploratores testantur, partem chyli
coactam, solito minorem fuisse. Hanc autem observationem omnino vitiatam
aestimo, eo quod bestia prussiatum potassae devoraverat, qui alio experimento,
integro liene, chylum fluidiorem quam solitum fecisse videtur. Macies partim
vulneri tribuenda est, partim canis graviditati, quinque enim foetus in tubis re-
perti sunt, qui miro quodam errore, quartum vel quintum mensem attigisse
dicuntur.
380 APPENDIX.
teriem colorantem pene deesse in iis, quibus arteriae exupe-
rant.
Nunquam mihi sepiam explorandi occasio contigit, scire
tamen exoptarem, num organum, quo atramentum secer-
nitur, cum mea conjectura congruat.
Si sanguis ad tines arteriarum, eo modo disponitur, quera
supra conjectavi, mihi videtur hoc ad sanguinis motum non-
nihil conferre debere. Sic in canalibus et rivulis objecta-
culis munitis, his apertis, fluxus inducilur. Similem quo-
que originem Cl. Franklin quibusdam procellis attri-
buit.
Imaginari non possum quomodo extremorum vasorum
contractions, circuitum sanguinis promovere possint.
Itaque non modo Cl. Bichat horum vasorum contrac-
tiones organicas, sed etiam actionem quam illis tribuit
Wilson Phillip, plane rejicio. Dispositionem sanguinis
ad tines arteriarum plus efhcere, quam ullam istorum vaso-
rum actionem, ex hoc argumentor. Scilicet ubicunque adest
seminatum ovum, sive in utero, in tubo, in ovario, vel etiam
in peritoneo, illic sanguinis cursus attrahitur.
Parum adhuc causam intelligimus, cur quaedam partes
prae aliis interdum insigniter increscant. Factum tamen
non incommode a Blumenbach exprimitur, et nisui for-
mativo attribuitur. Hoc in annua cervorum cornuum reno-
vatione conspicuum est, at hie quoque auctum sanguinis
cursum non primarium esse, sed secundarium, et supra
dicto more inductum, existimo. In foetibus corde caren-
tibus, sanguinis motum, ut opinor, multo melius huic causae
quam aut arteriarum contractionibus, aut alius foetus cordi,
attribuendum est. In vegetabilibus, cum nullum organum
ad succum movendum specialiter constitutum habeant,
multum actioni ei quae supra prolata est simillimae tri-
buendum est. Actio quam nunc ad sanguinis circuitum
auxiliarem protuli, mihi longe verisimilior videtur, quam
ea quae ad hanc finem imaginatus est Carson. At ne
quis existimet, me arterias non nisi tubos inertes habere.
Licet illis non attribuam facultatem ullam, qua sanguinis
circuitus effici possit, lubentissime concedo, motum san-
guinis ab aliis organis excitatum, modificationes ab arteriis
accipere. Sic ob vim resiliendi, ad motum inaequalem, ex
cordis alternanti actione provenientem, constantem et aequa-
bilem efficiendum tendunt. Ob tonicitatem morbo mutatam,
sanguinis rivum non semper eadem ratione amplectitur, et
inde partim oriuntur mirae pulsuum diversitates. Vasa
APPENDIX. 381
quoque in ipsum sanguinem agunt, et ejus conditionem
afficiunt.
Sic Heuson sanguinem in propriis vasis stagnantem,
solita, ratione non coire demonstravit. Hunc effectum sa-
gacissimus Hunter nequaquam ignoravit, et recentius
ingeniosus Blundell, hac de re non nulla experimenta
instituit. Non modo Gulielmi Heuson, de retardato
sanguinis in vasis coitu, assertionem bene confirmavit, sed
praeterea, vasa, postquam tunicae suae, aut frigore, aut
nicotiana infusa, aut alio quovis modo valde laesae sunt,
hac facultate sanguinem liquidum servandi carere demon-
stravit. Ex quovitam sanguinis ex mutua sed inexplicata
actione hunc inter et vasa sanguifera pendere, conjectavit.
Nonne igitur natura, in mirabili ilia functione, qua crea-
tionis opus quodammodo aeternum fecisse videtur, san-
guinem, ex quo faecundi humores formandi sunt, per Ion-
gas, tenues, et tortuosas arterias spermaticas transmisit, eo
proposito ut hypervitalis, ut ita dicam, evadat.
Haec enim conformatio in illis animalibus, quae hac
functione prae aliis pollent, ut in tauro et in ariete*, prae-
cipue observanda est.
Multum profecto de absorbendi functione, ad morbos
spectante disseri potest. Non modo multis in morbis ma-
ciem, signum quidem notabile inducit, sed etiam haec
functio laesa, non nullorum morborum origo, seu causa
proxima habenda est. Omnium pene consensu struma, et
quaedam hydropis varietates hue referuntur.
Nee multum abest quin mihi persuasum sit, febris ipsius
essentiam constare, in ea. functione laesa, vel pene sup-
pressa, qua. variae corporis partes assidue mutantur. Haec
autem quaestio multo copiosior est, quam ut hie tractetur.
Inflammationem quoque, ut opinor, et scorbutum, si func-
tiones cum absorptione conjunctae non nimis fuissent neg-
lectae, multo melius intelligeremus. At ne lectoris benevoli
patientia, diutius abutar, de his, itemque de Hydrargyri et
aliorum quorundam medicaminum in absorbendi functione
efFectibus, et agendi rationibus, conjecturas meas proponere
in aliud tempus differam.
* In excellent! opere Cuvieri, ornatissimi quidem Philosophi, et animalium
scientiae excultorum omnium facile principis, haec facultas in ariete multo mi-
noris aestimatur, ut abunde demonstrant facta, de quibus in Sussex comitatu
Anglico ovium cultura notatissimo, certior factus sum.
382 APPENDIX.
Since writing the preceding Thesis, I have had the ad-
vantage of perusing some valuable articles relating to
the subject of absorption, which have been written sub-
sequently to, or near the same time, with my Essay.
The most important of these, are two papers by Leo-
nardo Frunchini, published at Bologna, in 1823; that of
Fiscinus and Seiler of Dresden, republished in the " Journal
Complimentaire du Dictionnaire des Sciences Medicales ;"
that of Michael Fodera on Absorption and Exhalation ;
several papers by Regulus Lippi, Professor of Anatomy at
Florence ; and of Fohmann and Louth of Germany, on the
Anastomosis of the Lymphatics with the Veins ; the re-
searches of Dr. Barry on the Influence of Atmospheric
Pressure ; and of my friends, Dr. Addison and John Mor-
gan, on the Modus Operandi of Poisons.
I must not swell this volume with an analysis of these
publications; but restrict myself to mentioning the principal
facts which they severally relate, whether in support or
refutation of the statements which I have made.
It has been objected to the view which I have taken of
the function of absorption (p. 346.), that it is far too chemi-
cal ; but I would beg to state in reply, that I apprehend
that in this respect I have been somewhat misunderstood.
I am fully prepared to admit, that the science of chemis-
try, as it at present exists, is unquestionably inadequate to
explain many of the phenomena presented by animal life ;
but I consider, that as in many of these phenomena che-
mical affinities are counteracted, and numerous new chemi-
cal combinations formed, processes essentially chemical are
going forward, which we can never fully understand, even
to the extent which our limited powers will allow; unless
APPENDIX. 383
we investigate them with the assistance of chemistry. In
saying this, let me not be regarded as considering life as
merely a chemical phenomenon. The functions of living
organized beings involve the operation, not only of chemi-
cal, but of every other physical agency, and in our inves-
tigation of these functions, if we wish really to improve our
knowledge of the attributes of life, we must not reject our
knowledge of those agents, but rather regard whatever is
fixed in them as a known quantity, which may greatly
aid us in ascertaining other quantities, as yet unknown.
Scarcely any important step is taken in any department of
physical knowledge, which does not give us a clearer view
of some vital function. The labours of Nysten, Dr. Ste-
phens, and Dutrochet, afford good illustrations of this
assertion.
Those who feel interested in this subject, will do well
to read the Essay of Dr. Pritchard on the Doctrine of a
Vital Principle, which contains many important consi-
derations connected with the study of the phenomena of
life.
The permeability of the animal tissues, alluded to in the
second note, p. 349, is further considered in the sequel.
Page 350. The experiments of Dr. Edwards, referred to in
the first note, have been detailed in the previous part of this
volume.
The functions of the eighth pair of nerves, which are
glanced at in the second note, will be noticed in conjunc-
tion with the consideration of the influence of the nerves on
absorption.
Page 354. The elaborate article of Fiscinus and Seiler,
who conducted their enquiry at the Veterinary School at
Dresden, contains a much more detailed account of the
discovery and investigation of the lymphatic system, and
of the controversy which ensued, than I had met when
384 APPENDIX.
composing the Thesis, or than I have seen in any other
work since.
To the names of the early contributors to our knowledge
of the anatomy of the lymphatic system, which I have al-
ready enumerated, must be added those of Pecquet, Van
Horn, Rolfink, Severinus, Hilden, Wurm, and Highmore ;
and of a some what later period, Steno, Nuck, Stalport, Vander
Weil, Brunner, Rudly, Ruysch, Mery, Saltzmann, Wins-
low, and Blaes. — From the second half of the seventeenth
century, and during the first part of the eighteenth, Swalve,
Walaeus, Diemerbrceck, Lower, Pauli,Bohn, Cole, Wharton,
Gottsched, Blanch, Glisson, and Charleton, declared them-
selves in favour of lymphatic absorption. Two periods are
particularly interesting in reference to this subject during
the second half of the eighteenth century, viz., from 1780 to
1799, when the Hunters, Sograffi, and Heuson, and sub-
sequently, from 1780 to 1799, when Cruickshank, Mas-
cagni, Sheldon, Soemmering, Blumenbach, Ludwig, Haase,
Werner, Feller, Desgenettes, Oudmann, and Schreger, con-
tributed, both by experiments and arguments, to overturn
the old doctrine of venous absorption, which from the year
1798, was scarcely supported by any one.
Those who are disposed to investigate the controversy,
which was rather renewed than commenced by the Hunters
and their opponents, may consult Haller, Cruickshank,
Sheldon, Rezia, Mascagni, Lindner, Lupi, Soemmering,
Ludwig, Oudmann, and Lorinser.
Page 355. Although I have expressed a doubt as to the
propriety of admitting the capillary system, as proposed by
Bichat, from the idea that mere minuteness is not a suffi-
cient ground of distinction to lead us to separate, either the
small arteries, or veins, or lymphatics, from the set of ves-
sels to which they belong, the recent highly interesting ob-
servations of my friend, Dr. Marshall Hall, appear to afford
APPENDIX. 385
demonstrative evidence of a system of minute vessels, in-
termediate to the extreme arteries and veins, and anatomi-
cally distinct from both. '.< It is quite necessary," says Dr-
Hall, " to distinguish the capillary vessels from the minute
arteries from which they arise, and the minute veins to
which they belong. The minute vessels may be considered
as arterial, as long as they continue to divide and subdivide
into smaller and smaller branches. The minute veins, are
those vessels which gradually enlarge from the succession
of smaller roots. The true capillary vessels are obviously
distinct from each of these ; they do not become smaller by
subdivision, nor larger by conjunction, but they are charac-
terized by continual and successive union and division, or
anastomosis, whilst they retain a nearly uniform diameter."
The anastomoses of minute arteries, though mentioned
by many authors, the Doctor states to be of so rare occur-
rence, that after diligent search he has not been able to
meet with a single instance of them. Anastomes between
the roots of veins, he regards as not uncommon. These
differences between the true capillary vessels, and the arte-
ries and veins, have a manifest influence on the mode in
which the blood circulates through them. Its course be-
comes of only half its former velocity, and consequently the
particles, instead of moving too rapidly to be seen, become
distinctly visible.
Dr. Hall suspects, that the true capillaries are mere ca-
nals, instead of being real tubes, by which, I suppose him to
mean, that they are not possessed of distinct coats, inde-
pendent of the structure through which they pass. It is
obvious, that this difference must materially contribute to
modify their functions. (See Dr.M. Hall on the Circulation
of the Blood, a work abounding in important facts and
views.)
The existence of the capillary vessels above described, and
c c
386 APPENDIX.
the want of any sufficient proof, that either arteries or veins in a
state of integrity, are furnished, with open mouths, go far to
do away with the idea, that there is a peculiar structure void
of vessels intermediate to the termination of the arteries and
the origin of the veins. But the admission of the continuity
of the arteries and veins, through the medium of the capil-
laries, seems to imply the existence of a non-vascular struc-
ture, through which they circulate. The microscopic exa-
mination of the animal tissues favours the same conclusion.
Page 358. The fullest investigation of the communications
by which the lacteals and lymphatics, discharge themselves
into the venous system, is that which we owe to Fohmann,
Louth, and Lippi. The last author has justly received, as
the reward of his indefatigable labours, one of the prizes
awarded by the Royal Academy of Sciences of Paris, and I
cannot do better than refer the reader to his work, intitled
Illustrazioni Fisiologiche e Patolgiche del Sy sterna Linfatico-
Chilifero mediant e la scoperta di ungran numero di communica-
zioni de esso col venoso. It must be regarded as a valuable and
important contribution to anatomical knowledge, whatever
be the opinion entertained of the author's physiological views.
Some of these communications had also been described
by others, viz., those of the lymphatics of the broad liga-
ments with the hypogastric veins by Wepfer ; Steno had
pointed out those of other lymphatics, with the cava and
the axillary and jugular veins. Nuck traced those of the
arm to the lumbar veins ; Lobstein those of the spleen to
the vena portae ; and Mertrud others to the subclavian.
Seiler often saw mercury pass into the veins from the lym-
phatics. It frequently happened with the lymphatics of
the thigh, and was almost always the case when the me-
senteric glands were injected. The last mentioned fact
completely accords with the observations of Meckel, whose
opinion has been adopted by Falconer, Lindner, Ludwig,
APPENDIX. 387
Caldani, Wrisberg, Lenhossek, F. P. Meckel, and Ribes.
Page 359. Communications betiveen the internal surfaces
of various cavities and canals, and the lymphatic vessels. — Seiler
has often seen the lymphatics injected from the duct of the
pancreas, the vas deferens, and the canal of Steno. Walter
has observed the same thing in the lactiferous tubes. Lippi
filled the neighbouring lymphatics of the liver from the ca-
vity of the gall bladder. It frequently happens, that the
lymphatics of the liver and spleen are filled when those
organs are finely injected.
Page 359. Communication between the arteries and ab-
sorbents, or lymphatics. — Lippi says, that the lymphatics
arise from the arterial system, as well as from the surface
of membranes, and wherever secretion or effusion takes
place.
Page 360. Communication between the minute extremities
of lymphatics and veins. — Lippi describes the lymphatics of
the kidney inosculating with those of the emulgent veins by
a kind of capillary vessel.
The following authors may be mentioned, in addition to
those whose names are cited in the Thesis, as supporters of
the doctrine of absorption by the lymphatics : — Glisson,
Wharton, Derelincurtius, Needham, Lenoble, Collins, Van
der Sande, Sografi, Foelix, Ludwig, Feller, Haase, Oud-
man, Schreger, Fohmann, Lippi and Louth.
The work of Oudiman, is regarded by Fiscinus and Seiler
as an able performance in support of lymphatic absorption,
but they consider him not sufficiently rigid in the examina-
tion of the experiments of his party, nor does he attach suf-
ficient importance to the arguments of his opponents.
The experiments of Schreger, which are some of the
latest that have been brought forward to establish the ex-
clusive right of the lymphatic system to the character of
absorbents, claim particular consideration from the author
c c2
388 APPENDIX.
being an acknowledged good observer, as well as from his
having been previously a strenuous advocate of venous ab-
sorption. Yet, the opinions of both these experimentors,
but more especially of the former, appear to be nearly as
much founded on the inability to detect milk, and other
substances, in the veins, as on direct proofs of their absorp-
tion by the lymphatics. The following experiments of Schre-
ger's seem to require some confirmation or explanation.
A bandage was tied round the hind leg of a puppy, as near
as possible to the pelvis. The limb was kept twenty-four
minutes in tepid milk — the lymphatics were then filled
with milk — the veins contained none. The bladder of a
dog was filled with milk; the crural arteries were tied — in
twenty-four minutes the vesical veins were almost empty,
and the little blood which they contained, was unmixed
with milk ; but there was some in a few of the lymphatics.
In bleeding a woman from the foot, it happened, that a lym-
phatic vessel was divided ; there continually flowed from it
a quantity of lymph ; the lower part of the foot was im-
mersed in tepid water mixed with a solution of musk. The
lymph was collected in a cupping-glass, and blood was
taken from a vein opened on the upper part of the foot;
the former soom smelt of musk, the latter not in the least.
In at least one of the experiments performed by Fiscinus
and Seiler, it happened, that when madder had been given,
the chyle was remarkably red. In five of their experi-
ments, in which an alkaline solution of lead was either
given internally, or applied externally, lead was detected in
the chyle. Traces of arsenic, and also of nitrate of silver,
have also been found in the contents of the thoracic duct.
In two other experiments, in which turmeric had been
employed, the chyle presented a yellow colour, which was
heightened by the addition of an alkali.
Lippi, the friend and disciple of Mascagni, is the last
APPENDIX. 389
and most strenuous advocate for the doctrine of absorption,
performed by the lacteals and lymphatics, exclusively. T
have already alluded to the anatomical facts on which his
views are founded. These views manifestly present lym-
phatic absorption, under a modified character, in which it
seems to evade some of the objections urged against it by
the supporters of venous absorption; but they appear to
be liable to others, some of which, I have anticipated at
p. 367.
Page 365. Besides the recent experimenters whom I
have mentioned, and to whose labours I shall presently
revert, the following names may be added to the list of those
whom I have cited, as supporters of the ancient doctrine of
venous absorption, — Bills, Jacques de Back, Schneider,
d'Azout, Horn, Mortimer, Brendel, Darwin, Walter, Len-
hossek, Malfatti, Caldani, Lupi, Hartman, Prochaska,
Treveranus, Reil and Jseckel.
The experiment referred to at p. 366, was performed by
Segalas and read by him in the Royal Academy of Science
of Paris. I cannot omit this occasion for protesting against
inferences drawn from experiments, in which the functions
of the animal, or part of the animal, are so completely inter-
fered with, as they must have been in this instance, in which
the lymphatic vessels alone remained to connect the intestine
with the animal. This objection applies almost to the same
extent to the celebrated experiment of Magendie, in which
the poisoned limb was connected with the body of the
animal, solely by the means of the circulation maintained
through the pieces of quill, which united the divided vessels.
Though this experiment may succeed in the hands of the
able physiologist who devised it, yet it must be regarded
as one of the greatest difficulty, since, besides the objec-
tion already urged, there is another of equal practical im-
portance in the coagulation of the blood in the quills. This
390 APPENDIX.
obstacle proved insurmountable, in various attempts made
by my friend J. Morgan, and equally defeated another dis-
tinguished physiologist, who attempted to repeat the experi-
ment. It may be objected against some of the experiments
performed by Magendie, that the production of the peculiar
effects of a poisonous agent, is no sufficient proof of that
substance having been absorbed. This is fully admitted by
Franchini, especially in those cases in which the quantity
of poison employed is very small, and the operation of the
poison is violent and rapid. The strongest confirmation
of this objection, is furnished by the researches of my
friends, Dr. Addison and J. Morgan, respecting the ope-
ration of poisons on the living body. They have clearly
proved, that the effects of poisons do not depend on
the contamination of the fluids circulating through the
system. A connection having been established between
two dogs, by means of the large vessels of their necks, the
blood from the one, expiring under the influence of a poison,
with which it had been inoculated, was transmitted with
impunity into the second. To render this trial as complete
as possible, a mutual interchange of blood was established,
the trunk of the carotid of one dog supplying the branches
of the other, and the jugular vein of one discharging itself
into the heart of the other. The animal, which had not been
wounded with the poison, exhibited not the least indication
of its influence. Although the widely received doctrine,
which ascribes the influence of poison to absorption, and
more especially to venous absorption, is thus invalidated,
the question of absorption is left untouched. Without
reference to the effects produced on the system, it is very
evident, that many substances are introduced, with little
change into the body, though the channels by which they
do so may elude our search. Leonardo Franchini, a disciple
of the old doctrine, undertook his experiments with a view
APPENDIX. 391
to elucidate this subject. He repeated with great care, the
various experiments of Lister, Musgrave, Hunter, Haller,
and others, who have described the absorption of coloured,
odoriferous, and other substances, by the lacteals and lym-
phatics, but his results drawn from fifty experiments, most
essentially differed from theirs. On the other hand, he
found many of those substances in the blood of the vena
portse, and other veins. He sums up the results of his ex-
periments, in the following conclusions: — 1. " The white,
or lymphatic vessels of the intestines, are the true absorbents
of the chyle. 2. It is not proved, that they absorb any
other fluids from the interior of the intestines. 3. There
are no valid arguments by which it is proved, that the lym-
phatic vessels of other parts are absorbents. 4. The veins
certainly absorb from the interior of the intestines, from
the cavity of the abdomen, and from the bronchi. 5. It is
not proved by experiment, whether the lymphatics of the
veins absorb from the minute cavities of the cellular mem-
brane, and from the interstices of the different tissues. 6.
Many facts, both physiological and pathological, render it
very probable that the absorption of fluids from these cavi-
ties, is, at least, to a great degree, performed by the san-
guiferous vessels." Perhaps, the most important and ori-
ginal part of Leonardo Franchini's paper, consists in the
satisfactory explanations which he has offered of some of the
contradictory statements, which the supporters of the con-
flicting opinions have advanced. He had frequently re-
peated the experiments of Lister, Musgrave, Hunter, Haller,
and others, in which indigo, and other blue pigments, had
been employed, without perceiving any blue colour in the
lacteals, or lymphatics ; when on one occasion, having kept
the animal fasting longer than usual, he observed that these
vessels presented a light blue tinge. At first he conceived
that the protracted fasting had favoured the absorption of
392 APPENDIX.
the colouring matter ; but having afterwards observed the
same appearances, produced after continued abstinence,
whether the blue colouring matter had been given or not,
and even when a red pigment had been employed, he was
led to discover that the blue tinge of the vessels, was no-
thing else than their natural appearance when filled with a
limpid fluid. He placed some of the fluid from these ves-
sels on white paper, and found that it did not present the
slightest trace of any blue pigment : he examined it with a
microscope, with the same result. Having made this dis-
covery, with regard to the apparent absorption of blue pig-
ments, he looked for similar explanations of those cases, in
which other colours appeared to have entered the lympha-
tic system. Although in his own experiments, he had
never seen anything to make him believe, that undigested
milk is ever taken up by the lacteals, or lymphatics, he
found that a mistake might easily be made, by not dis-
dinguishing milk from the true chyle, and he believes, that
in those cases, in which milk is reported to have been found
in these vessels, chyle, the product of a previous meal, or
of the digestion of the milk itself, had been mistaken for it.
Though, I believe, this last explanation of Franchini,
may, in some cases, be correct, there are others to which
it does not apply, as I have already observed, in noticing
the same objection as urged by Professor Magendie, see
p. 327. In respect to the absorption of red coloring mat-
ters, Franchini made observations, similar to those above
noticed, respecting blue pigments ; at first it appeared
that some absorption of madder really took place when the
animal had been long fasting ; but he discovered that the
same red, or pink tinge, might be produced when the ani-
mal had taken no colouring matter, or even matter of a dif-
ferent hue. The red colour could not, like the light blue,
be ascribed to an optical deception ; but an explanation of
APPENDIX. 393
its occurrence was found in the fact, that after long fast-
ing, the fluid in the lymphatics and lacteals, really posses-
ses a reddish colour, which is sometimes proper to itself,
and at other times appears to be owing to an accidental ad-
mixture of blood.
Fiscinus and Seiler, may be numbered amongst those
experimenters, who have most unequivocally proved the
absorbing power of the veins, but they do not go so far as
Magendie and Franchini, in restricting the office of the
lacteals to the absorption of chyle only. They do not con-
sider it as proved, that the lymphatics in other parts of the
body are endowed with the power of absorption. Although
their numerous and varied experiments appear to have
been conducted with great care, they candidly admit, that
they do not consider the subject of absorption as by any
means settled.
The results of their experiments may be briefly stated as
follows: — 1. They found indigo in the venous blood, but
not in the chyle or lymph. On two occasions, a slight
trace of turmeric was detected in the chyle, but they in vain
sought for lac, madder, and indigo, in this fluid. They
confirm the frequent appearance of a red tinge in the chyle
and lymph, when no red colouring matter had been given.
2. The odour of DippePs empyreumatic animal oil was
frequently met with in the venous blood, never in the chyle
or lymph. They do not appear to have found camphor in
either.
3. They generally found prussiat of potass in the venous
blood and urine, but only in one or two occasions, a trace
of it in the lymphatic system. In five experiments they
found traces of lead in the chyle, when an alkaline solution
of that metal had been employed. They appear likewise to
have found this metal in the venous blood. Nitrate of
silver and arseniate of potass, produced indications of silver
394 APPENDIX.
and arsenic, both in the blood and chyle. They support
the observations of Wollaston and Marcet, respecting the
occasional presence of foreign matters in the urine, when
they cannot be detected in any of the other animal fluids.
They object to the lymphatics being possessed of a secern-
ing power so delicate, that having absorbed all substances
indiscriminately, they transmit some entirely to the veins,
whilst they retain others and convey them to the thoracic
duct. They think it far more accordant with the laws of
affinity, which regulate organized bodies, that vessels con-
taining venous blood should take up certain substances^
which are insusceptible of being absorbed by the lympha-
tics, whose structure is different.
Page 367. The celebrated Rasori, whom I had the plea-
sure of visiting at Milan in 1824, informed me that he had
published, in the Annals of Science and Literature for
1810, some facts relating to absorption and the passage of
substances into the urine, but I have not had the advantage
of a reference to that paper.
Page 368. What are the properties which render some
substances liable to absorption by the lacteals, and what
are those which render others liable to absorption by the
veins ? Since the original publication of the Thesis, I
have had but little opportunity of inquiring into the accu-
racy of the principle which I there proposed ; but so far as
I have been able to do so, either by observation, or by ap-
peal to the results obtained by more recent experimenters
I am led to comfirm rather than recede from the opinion
which I there advanced. The following experiment was
performed with a view of observing the effect, produced by
giving a decidedly alkaline character to the contents of the
stomach and intestines, without rendering them of a more
irritating quality than could be avoided ; and also, of trying
a peculiar pigment, which is both an animal substance, and
APPENDIX. 395
of a colour not liable to be confounded with any of the hues
which the lacteals, or lymphatics, or their contents, may
present.
The subject of this experiment was a full grown, half-bred,
bull bitch, which had pupped about three weeks before.
After fasting for about twenty-four hours, she received some
calcined magnesia in new milk — this was taken with avidity
— The object was to remove all acid from the intestinal
canal. This dose was repeated. Sub-carbonate of soda
coarsely powdered was next given her at short intervals'
inclosed in small pieces of fresh boiled horse-flesh, and
some of the same salt was also given to her dissolved in
milk. She took both almost without hesitation, though
the salt was very imperfectly concealed. Some of the
green pigment taken from the placenta of a bitch, was
also given with some of the same kind of meat. This pig-
ment was previously examined with test paper and proved
to be neutral ; it was, however, rather putrid, having been
taken from the uterus of a bitch killed more than a week
before. This pigment had been found not to change colour
by the addition of either alkali or acid. The fragments of
meat in which this pigment was given were taken with
great hesitation, unless considerable pains were taken in
concealing it, or the piece caught in the air and bolted.
The administration of these different articles lasted about
three-quarters of an hour, and was completed about one
P. M. ; about 51J of magn. calc. had been given, and nearly
three-quarters of an ounce of soda sub-carb. She after-
wards lay quietly. She was killed at about half past one
o'clock by a blow on the head. The abdomen was quickly
opened. The contents of the stomach and small intestines
were decidedly alkaline, as shewn by restoring the blue co-
lour of reddened litmus paper. In dying, the animal passed
396 APPENDIX.
a copious watery digestion, which appeared also alkaline.
The chyme was coloured by the green matter which had
been given, and which was not altered by the juices of the
stomach. The lacteals, more particularly those from the
upper part of the intestinal tube were filled with perfectly
white chyle, which possessed decidedly alkaline proper-
ties. The thoracic duct was also turgid with the same
fluid, about two or three drachms of this were col-
lected perfectly pure. It was quite white, and had the
appearance, as to consistence, of very rich milk. In
little more than half an hour it coagulated into a thick
grumous mass, and acquired a just perceptible shade
of pink or lilac. The blood from the mesenteric veins
was collected in large quantity ; it coagulated in a short
time — no streaks of chyle could be observed in it, but
an appearance resembling this, was in one instance ma-
nifestly produced by the division of a small lacteal ves-
sel, which passed over the vein at the part where it was
opened. This blood was alkaline, both when examined as
it flowed from the vessel, and when coagulated, and sepa-
ration had taken place ; but it was less so than the chyle —
the serum was remarkably limpid and colourless. A little
acetic acid diluted with water was thrown into an emptied
portion of intestine, included between two ligatures, but
vitality was too far gone for this to be considered part of
the experiment.
The result of this experiment, which I do not offer as
conclusive, is, at least, favourable to the idea that the
lacteals are disposed to receive alkaline fluids. The com-
plete rejection of the colouring matter accords with the
almost uniform result obtained by all recent experimenters.
This part of the subject may be pretty much regarded as
settled, since the chyle, of the mammalia at least, examined
APPENDIX. 397
after a meal of their ordinary food, is universally described
as white, or very nearly so, or slightly tinged with red ;
whilst the food or chyme, from which it was produced, may
have presented every variety of colour. Two slight excep-
tions are indeed related by Fiscinus and Seiler, in which a
trace of yellow was perceived after the administration of
turmeric, and in another instance, a similar effect was pro-
duced by rhubarb. A similar exception is already stated,
with respect to rhubarb, in the Thesis ; and another in the
case of the colouring matter of bile ; it would seem, there-
fore, that some yellow colouring principles are decidedly
susceptible of lymphatic absorption. The cause of their
forming an exception to the general rule, seems to merit
farther inquiry.
Page 371. I have stated, that some neutral salts are
taken up, both by lymphatics and veins. I find this ob-
servation confirmed by additional authorities. Those which
have metallic bases, appear particularly of this number —
lead, iron, silver and arsenic, having all been detected, both
in the chyle and blood. Prusiate of potass appears almost
constantly to enter the veins ; yet, by several experimen-
ters, it has been occasionally detected in the chyle, or lymph •
but it would appear, that a considerable interval of time must
elapse for this to take place. Hence, it may be questioned,
whether the salt may not have found its way into the lym-
phatic system, through some communicating vein, or artery,
and not in the ordinary course of absorption.
The absorption of fixed oils, by the lacteals, seems to be
fully confirmed by Tiedmann and Gmelin, in their elabo-
rate work on digestion, although their rivals, Leuret and
Lassaigne do not appear to have arrived at the same con-
clusion.
The absorption of acid substances, by the veins, has
398 APPENDIX.
been proved by various authorities, which have come to ray
knowledge since the publication of the Thesis.
Dr. Stephens has satisfactorily shown, that it is the com-
, mon effect of all acids to blacken the blood by admixture with
it out of the body, and the observations, both of himself and
others, show that the same effect is produced when they
are administered to the living animal. The alteration that
takes place in the transition from arterial to venous blood,
which I could only offer as a probable confirmation of this
view, is now demonstrated to be owing to the accession of
carbonic acid. Acetic acid has been shewn, by Franchini,
to be taken up by the veins, not indeed in a free state, but
forming an acetate with the alkali of the blood.
I do not pretend to lay much stress on the following ob-
servation, as it was made some time after death ; but it
tends to show that sulphurated hydrogen, which in some
respects is allied to the class of acids, has a stronger ten-
dency to be taken up by the veins, than by the lacteals. A
patient in Guy's Hospital, had for a considerable time been
labouring under constipation, occasioned by a stricture
near the termination of the colon. For three weeks before
his death, nothing passed from his bowels. On inspection,
the intestines, small and large, were found prodigiously
distended with fluid fcecal matter, and abundance of gas ;
the latter, which was allowed to escape from a small aper-
ture, was proved to be sulphurated hydrogen, not only by
its insufferable odour, but by the characteristic blue flame
with which it caused a lighted taper to burn. A small
quantity of blood taken from the mesenteric veins of this
subject, was placed unmixed with any substance upon a
piece of clean paper and conveyed to a distance, to be
smelt by different persons who had not been present at the
inspection, and who immediately recognized the smell of
APPENDIX. 399
sulphurated hydrogen. A similar trial was made with
lymph from the thoracic duct, but no smell was perceived
in it.
Page 374. Respecting the question as to the causes by which
absorbed materials enter the vessels. — I do not know that I
can allude more suitably than in this place to the views of
Dr. Barry, respecting the circulation through the veins,
although their application to the subject of absorption forms
only a part of their interest. It was far from being a new
idea, that the blood returned towards the heart, in conse-
quence of some other force besides the vis a tergo derived
from, the impulse given by the left ventricle of the heart ;
yet, I believe, no one before Dr. Barry, had had the merit
of proving, although Huxham had suspected*, that the
venous blood was, as it were, pumped towards the chest.
Dr. Barry has shewn that the pressure of the atmosphere,
is the agent by which this is effected. It is well known,
that when an animal extends the capacity of its thorax, by
the elevation of its ribs, and the descent of its diaphragm,
the atmospheric air penetrates through the larynx and
trachea, and fills the pulmonary cells. But it is not only
the cavities which are destined to receive air which are
filled — the pulmonary veins, and the branches of the
cavae within the chest, are similarly, though not equally
dilated . The resistance of the flow of venous blood towards
the heart being removed, this blood is sent forward by the
pressure of the atmosphere, which becomes a powerful as-
sistant to the remaining influence of the heart.
The following experiment of Dr. Barry, seems to place
this beyond a doubt. A spiral glass tube was fixed, with
the intervention of a gum catheter, by one extremity to the
jugular vein of a horse, whilst the other was immersed in
* See Marshall Hall on the circulation.
400 APPENDIX.
a coloured fluid. At each inspiration of the animal, the
coloured liquid was observed to rise in the tube whilst it
was stationary, or even descended during expiration. This
experiment, as well as several others, essentially the same
in principle, though variously modified, was frequently re-
peated by Dr. Barry, in the presence of the members of the
commission appointed by the Institute, and many other
distinguished physiologists, several of whom have given
their public testimony to the uniform and unequivocal re-
sults of these experiments. When the hand of the operator
was introduced into the abdomen of a living horse, and ap-
plied to the vena cava, that vessel was found to be sensibly
distended during expiration, and partially to empty itself
during inspiration. The Doctor was not satisfied with
proving, that fluids were pressed along towards the heart,
in veins, and in tubes connected with them, whenever the
chest was dilated by inspiration ; he showed, that the same
effect was produced in tubes communicating with the cavi-
ties of the pleurae and the pericardium. In making the appli-
cation of this view of the pressure of the atmosphere, as an
agent in carrying on the circulation of the blood, Dr. Barry is
by no means disposed to limit it to the venous trunks and larger
branches. He believes that through their intervention it
is felt in the most minute branches, where he believes it
becomes important, as the means by which absorption is
effected. He represents this fact as practically known to
the ancients, who, as Celsus informs us, were in the habit
of employing cupping glasses to obviate the effects of poi-
soned wounds. The Doctor performed may experiments,
with a variety of active poisons, on several species of ani-
mals, and found that the removal of the pressure of the
atmosphere, by means of cupping-glasses, was a certain
means of suspending the operation of the poison ; whence
he concludes : first, that neither sound nor wounded parts
APPENDIX. 401
of the surface of a living animal can absorb when placed
under a vacuum ; secondly, that the application of the va-
cuum by means of a piston cupping-glass, placed over the
points of contact of the absorbing surface, and the poison
which is in the act of being absorbed, arrests or mitigates
the symptoms caused by the poison ; thirdly, that as the
veins communicate more freely and directly with the chest
than the lymphatic system, they must be the more active
absorbents. He thinks that the absorbing powers of the
different tissues are in proportion ; first, to the pressure to
which their veins are exposed ; secondly, to the freedom of
communication with the thoracic cavities; thirdly, to the
permeability of the mouths and coats of the veins ; and,
lastly, to the number of the veins. Although I have no
hesitation in admitting, that Dr. Barry has performed an
important service to physiology, in demonstrating the
part which atmospheric pressure performs in assisting
in the circulation of the blood ; yet, I must confess a
doubt, as to its having any material influence in pro-
moting absorption, except indirectly through the me-
dium of the circulation. His experiments, connected with
this part of the subject, are neither questionable nor un-
important, but they admit of an explanation different
from that which he has given. The pressure of the
edge of a cupping-glass, under which a partial vacuum
has been produced, is not only an effectual interrup-
tion to the circulation in the part, but, likewise, cuts it
off from nervous influence. That it is the production
of this pressure, rather than the removal of that of the
atmosphere, is almost demonstrated by the experiments of
the late Thomas Ellerby, by which he shewed, that a cup-
ping-glass, firmly pressed upon a part without removing
the atmospheric pressure, afforded the same impediment as
the exhausted glasses used by Dr. Barry. Even a simple
D D
402 APPENDIX.
ring, or open cylinder, produced the same effect. Experi-
ments, nearly similar to those of T. R. Ellerby, have since
been performed in Philadelphia, by Dr. Pennock, but with
this exception, that he employed the pressure of a solid
body over the spot to which the poison was applied. He
found that the action of the poison was suspended, so long-
as the pressure was continued.
Imbibition, or the soaking- of fluids through the inert
pores of the coats of vessels, and other tissues, has been
considered by Magendie, as constituting the essence of ab-
sorption. I have briefly noticed in my Thesis, an objec-
tion to which this idea appeared liable. The subject has
since been carefully investigated by Fodera ; and many
physiologists, amongst whom may be mentioned Panizza,
are supporters of this doctrine.
It seems, therefore, necessary to offer a brief account of
it, as well as of the observations upon which it is founded.
In this view of the subject, absorption and exhalation are
regarded as imbibition and transudation. That is to say,
merely the effect of capillarity. It is shewn by an experi-
ment of Magendie's, repeated and confirmed by Fodera,
that if a portion of vein, or artery, be detached from the
neighbouring parts, and stripped of its cellular membrane,
but suffered to carry on the circulation, and some active
poison be applied to the surface, the specific effect of the
poison will be produced, although the utmost care may have
been exercised to prevent the application of the poison to
any other part. The fact of the imbibition of the poison, is
not inferred from its effect alone, but from its actual pre-
sence in the interior of the vessel. The converse of this
experiment was tried by including the denuded portion of
artery between two ligatures, and filling it with the poison
which produced its effect in this instance also. A portion
of the intestine of a living rabbit was included between liga-
APPENDIX. 403
tures ; the mesentery was likewise tied, that there might be
no vascular communication between the animal and the
portion of the intestine so included. A spirituous solution
of extract of nux vomica was then introduced into the por-
tion of intestine, which was then returned to the abdomen.
Poisoning took place1 as before. This experiment was re-
peated in a more conclusive manner, by introducing a con-
volution of the intestine of one animal, containing poison,
into the abdomen of another animal. This second animal
died from the poison, although there could be neither nervous
nor vascular communication with the cavity in which it was
lodged. He substituted sulphuretted hydrogen for the so-
lution of nux vomica, and found its effects produced on the
animal — proving, that gases, as well as liquids, are capa-
ble of penetrating through the animal tissues. These re-
sults were confirmed by numerous experiments upon re-
cently killed animals, until Fodera, and his friends, were
fully convinced, that this kind of imbibition really took
place. He placed different fluids in different cavities of the
body ; as for example, a solution of prussiate of potass
in the thorax, and a solution of sulphate of iron in the ab-
domen : it was not lono- before a blue colour was observed
in the chest and abdomen, and in different parts of the
body, showing, that not only had both fluids transuded, but
what appeared more remarkable, that transudation and im-
bibition wrere taking place simultaneously, and through the
same membranes. This curious fact was put to the test in
several experiments, by which it appeared to be indisputa-
bly confirmed : at least I see no reason to call it in question in
the cases which Fodera has related. There is, however, one
objection to the application of this principle, which, though
not overlooked by Fodera himself, seems to be possessed of
more importance than he has ascribed to it. This objection
is the same that was long since urged against experiments
dd2
404 APPENDIX.
of the same nature, as we may learn from the quotation
from Celsus already cited : — " Non quicquam esse stultius
quam quale quidque vivo homine est, tale existimare esse
moriente, imo jam mortuo."
The experiments of Fodera being, in most instances, tried
upon dead, or dying animals, or when living animals were em-
ployed, with substances so completely foreign to the animal
economy, that we may fairly suspect the vitality of the
parts to have been somewhat impaired ; may very reasonably
be supposed to have allowed the inorganic function of tran-
sudation and imbibition to have been in operation, to an
extent which the unimpaired powers of life could not have
tolerated. The following considerations lead me to believe,
that this suspicion is correct — if there were a constant
and reciprocal transudation and imbibition going forward
throughout the tissues of the living body, the result would
necessarily be the presence of every principle in every part
of the body, and a far greater uniformity in the chemical
composition of all the fluids and solids, than actually exists.
It is well known that those animals which secrete the
.most deadly poisons, are by no means exempt from the fatal
effects which follow the introduction of the poison into a
wound. For example, the sting of the scorpion is as fatal to
his own, as to any other species; yet, each individual car-
ries his reservoir of poison about with him with perfect im-
punity, although it is only cut off from the rest of his sys-
tem by a membranous sac. The existence of many partial
dropsies, may be urged as another illustration of the limit-
ation which life sets to transudation and imbibition. It is
well known that during life, the large intestines are often
distended with sulphuretted hydrogen, without the neigh-
bouring parts appearing to suffer from its proximity ; yet,
after death, a short time is sufficient for these tissues to ac-
quire, to a considerable depth, the peculiar leaden hue
APPENDIX. 405
which it imparts. The yellow tinge, which the parts in the
neighbourhood of the gall bladder commonly receive after
death, has long been pointed out as a striking example of
the difference between dead and living matter, with respect
to imbibition. The investigation of this subject, requires
the application of the principle to which I have more than
once referred. The tendency to transudation and imbi-
bition, doubtless exists in the living, as well as in the dead
structures ; but in the former, it is controuled by a mysterious
power which we can only judge of by its effects, and which
we cannot better investigate, than by examining the mode
in which it resists other powers with which we are better
acquainted. The experiments of electricians have so fully
confirmed the fact, that electricity, or galvanism, has a
powerful influence on the internal movement of fluids,
and their transmission through almost impervious sub-
stances, that it is by no means surprising that this agent
has been referred to ; yet, it is very important that we
should remember, that we may have only similarity, and not
identity of action, and consequently, only employ the facts
as assisting our analogical reasoning. The investigations of
Dutrochet, a brief account of which is given in a subse-
quent part of this Appendix, appear to point to a principle,
which, whether electricity be concerned or not, is in all
probability most intimately connected with many vital phe-
nomena, but more especially with absorption, nutrition,
and secretion. These researches not only prove the strong
tendency which some fluids have to pass through porous
bodies — they also confirm the observations of Fodera, con-
cerning the simultaneous existence of opposite movements,
and what appears to be of no small importance, they show
how much these movements of imbibition, and transudation,
are influenced by the nature of the porous body, and by that
of the fluids in contact with it. Instead, therefore, of re-
406
APPENDIX,
garding imbibition, and transudation, as phenomena that
do not take place in organized beings until life is extinct,
we may regard them, when variously modified, as concerned
in most of the essential functions of life.
The difficulty of admitting a power of selection possessed
by different sets of vessels is very much done away with,
and our ideas respecting the molicular changes attendant on
nutrition, secretion, and absorption simplified ; when, in-
stead of referring them to supposed and imaginary mouths,
or extremities of vessels, we may regard them as taking place
through the sides of the most minute vessels throughout
their course. The difficulty respecting the removal of
solid parts, is in particular very much removed. I have
repeated in my Thesis, with reference to this point, the
remark of Bichat; that entire decomposition takes place
prior to absorption, in consequence of which, they may pass
into the circulation in a fluid form. May we not conceive
the solid parts of the body, such for example, as the most
minute fibrillar of muscles, nerves, cellular membrane, &c,
which the most powerful microscopes can place within the
limits of our vision, and the more amorphous elements of
some of what are called parenchymatous structures, con-
stantly, as it were, washed by the fluids just transuding
from, or about to enter the minute vessels which pervade
them, and giving up to them those elements which are to
be thrown off from the system, and receiving others which
are to be deposited in their place. The continual succes-
sion of new parts will therefore depend, as I have already
suggested, not only on the joint operation of depositing and
absorbing vessels, but also on the nature of those particles
which they are destined to reinforce or succeed. See p. 377.
I am aware here that I have been tempted into a mere
speculation, and I ask the reader's excuse for intruding it
on his attention. Whatever be the precise mode in which
APPENDIX. 407
the vessels influence the fluids they contain, or by which
they are surrounded, and whatever be the changes taking
place in those minute structures, to the support of which
these vessels and their fluids are subservient, it is manifest
that they are liable to various influences and changes, very
distinct from anything which takes place in materials not
possessed of life. Physiologists, almost by common consent,
point to the nervous system as the medium through which
this mysterious influence is conveyed. Notwithstanding the
very important advances which have been made in the phy-
siology of the nervous system, it is still the department in
which most remains to be done. Justice seems to require,
that I should not omit this opportunity of mentioning the
laborious, but neglected and almost unknown work of Bel-
lingeri, who appears in part, at least, to have anticipated
our ingenious and meritorious countryman, Sir C. Bell, in
the distinction which he has made between the respective
functions of particular nerves. He plainly distinguished
that portion of the fifth pair which does not belong to
the semilunar ganglion from that which does so, and
pointed out the former as a nerve of motion, as Palletta
had previously done. He also described the seventh pair
as supplying motive influence to the same parts which re-
ceive the ramifications of those branches of the fifth, which
proceed from the semilunar ganglion ; but as he makes the
seventh pair subservient to the functions of animal life,
he did not separate the motive from the sentient nerves.
See the Inaugural Dissertation of C. F. J. Bellingeri,
published at Turin in 1818.
For the knowledge and use of this extraordinary thesis,
I am indebted to my friend S. D. Broughton.
With reference to this interesting subject, I cannot for-
bear to mention another circumstance, to which I can offer
my personal testimony, and which, I trust, will contribute
408 APPENDIX.
to allay the jealousy that has been excited in the minds
of some. — I passed the winter of 1821-22, in Paris, and
was frequently present at the meetings of the Institute.
On one of these occasions, I had the pleasure of hearing
some of the experiments and inductions of our distin-
guished countryman, related by Professor Magendie, who
passed a just encomium on their author, and admitted the
importance of the views which they opened. It can hardly
excite surprise, that when this act of justice had been per-
formed, the distinguished physiologist of Paris should him-
self enter the promising field that was laid open to him,
and that his skilful hands should have collected some of
the fruits, without abstracting, as has been too gratuitously
suspected, from the labours of his predecessor.
Although most important steps have been taken in the
physiology of the nervous system, not only in the estab-
lishment of the distinction between the nerves of sensation,
and the nerves of motion, but also in the improvement of our
knowledge of the anatomy of the brain, and the approach
to the determination of the functions of several of its parts,
which we owe to Dr. Foville, Flourens, Desmoulins, Ma-
gendie, Mayo, and others ; yet, there are several points
respecting which, we still continue in almost perfect igno-
rance. This is particularly the case with the part which
the nerves are supposed to perform in secretion, and other
vital phenomena of a chemical character. This influence,
whether real or merely imaginary, we may designate, for
the sake of convenience, by the term, chemical influence
of the nerves. Many distinguished philosophers and phy-
siologists have adopted the idea, that this influence is iden-
tical with galvanism. Dr. Young says, " We may imagine
that at the subdivision of a minute artery, a nervous fila-
ment pierces it on one side, and affords a pole positively
electrical, and another opposite filament, a negative pole."
APPENDIX. 409
Rolando, who was disposed to dispute the palm of merit
with Sir Charles Bell and Magendie, as a successful inves-
tigator of the nervous system, attached considerable im-
portance to his having represented the cerebellum as a sort
of electromoter, and formed a theory for the explanation of
the nervous influences, upon the basis of electricity. Dr..
Wilson Philip has particularly distinguished himself, as a
staunch advocate for the electric character of the nervous
agency. Nevertheless, if we except the experiments which
have been adduced by the last mentioned author, we shall
find that we have little more than a shrewd suspicion, sanc-
tioned by high authority, for the adoption of the theory. The
observations of Dr. Philip, as well as those of Prevost and
Dumas, whohave trodden in nearly the same path, have been
called in question, or attempted to be variously explained
away. Hence, it may not be amiss briefly to examine what
is actually known, and distinct from conjecture, in con-
nexion with the subject. It is by no means easy, effectually
to separate even a part of the body so completely from the
influence of the nervous system, as to render the experiment
conclusive in this respect, without at the same time so com-
pletely interfering with the circulation, as entirely to viti-
ate the experiment by its complexity. A considerable por-
tion of the body and limbs may be completely paralyzed, as
to sensation and motion, and considerable wasting may take
place, in consequence of the want of activity of the mus-
cles, and an inferior supply of blood. The process of nu-
trition is nevertheless carried on, and a certain degree of
irritability remains, as shown by the paralyzed part being
still susceptible of the influence of various agents — blisters
will rise, and eruptions and ulcers may form, and also heal.
Moreover, when this kind of paralysis has been most com-
pletely produced by the division of the spinal marrow, or
of nerves near their origin, the effects of active poisons ap-
410 APPENDIX.
plied to wounds in the part are not intercepted, although
it has been shown by the experiments of Dr. Addison and
J. Morgan, already noticed, that the operation of the poison,
is not to be ascribed to its introduction into the circulation.
To explain this difficulty, recourse has been had to branches
of nerves derived from the sympathetic system, and sup-
posed to accompany the branches of the vascular system.
Still, however, nothing is known of these branches, and we
have no direct experiments to throw any certain light on
their functions. The observation respecting the influence
of these nerves on the function of absorption, founded on
the experiments of John Hunter, and others, offered at
p. 371 of the Thesis, may, perhaps, be regarded as an
approach to an experimental inquiry into the subject.
The intestines being solely supplied by nerves of the sym-
pathetic system, and the facilities which they offer for the
division or the ligature of these nerves, render them rather
peculiarly adapted for this investigation. Though no posi-
tive conclusions can be drawn without the assistance of a
greater number and variety of experiments, yet those which
have been adverted to, seem, at least, to indicate the pro-
bability, that the vessels, when unassisted by the nervous
influence, lose much of their power of selection. Numerous
experiments have been made upon the division of the eighth
pair of nerves, with the hope of obtaining some light on the
subject of nervous influence. But although these nerves
offer some manifest advantages for experiment, from their
size and distinctness, and the readiness with which they
can be divided, with comparatively little injury to other
parts, and the character and importance of the functions
of those parts to which they are distributed, yet it ap-
pears to me, that they are liable to some decided objec-
tions. It is evident that they have so complex an origin,
that it is impossible to say, whether, at the point at which
APPENDIX. 411
division is to be made, the fibrillse belong more to the
motive, or the sentient nerves. The gangliform enlarge-
ment, which is sometimes very evident at the upper part,
would seem to place them amongst the sentient nerves,
and favour the suspicion as to their function, noticed at
p. 350. On the other hand, this nerve did not appear
in the experiments of my friend, S. D. Broughton, to be
possessed of sensibility; and the experiments of Drs. Wilson
Philip and Hastings, and those of Dr. Milne Edwards, and
others, exhibit this nerve as acting by virtue of an influence
directed from the brain to the branches, and in this res-
pect more allied to the motive, than to the sentient nerves.
Dr. Holland, although an opponent to the views of Dr.
Philip, at least, agrees with him in this respect, and re-
gards this nerve as communicating an influence to the lungs,
by which the circulation of the blood through them is pro-
moted. The disturbance of respiration, and digestion, ac-
companied by an accumulation of mucus in the lungs, and
the alteration of the secretions of the stomach, which suc-
ceed the division of the eighth pair of nerves, he regards as
secondary to the interruption of the circulation through the
lungs, which is a direct effect of the division. The destruc-
tion of different parts of the brain, and spinal marrow, does
not appear to have thrown any certain light on the influence
which the nerves exert upon the circulation through the
capillaries, in which their chemical agency is chiefly ex-
erted. It appears evident, that this destruction produces
a disturbance in this part of the circulation ; but the expe-
riments of Dr. Marshall Hall have shewn, that the same
effect is produced by the sudden destruction of other parts;
as for example, the stomach. This interesting fact, as well
as the operation of poisons inserted into a wound, seems to
point at a kind of sympathy, or consent of parts, with
which we are at present wholly unacquainted.
412 APPENDIX.
Dr. Foville has recently advanced some highly inter-
esting observations and speculations, concerning the joint
agency of the extreme branches of vessels and nerves,
which have been greatly admired by some of the ablest
physiologists in France, and which will, I hope, before
long be laid before the public.
Page 378. That the production of black matter is pro-
moted by the retardation, or stasis of blood in the ves-
sels, as suggested in the Thesis, appears to be strongly
confirmed by the effects of inflammation. It not unfre-
quently leaves the small vessels of the part affected, dis-
tended with blood, after the activity of the circulation
through them has ceased ; this is strikingly the case with
the mucous membrane of the alimentary canal, in which
the production of black matter from this cause is by no
means unfrequent. In some instances we may notice the
different shades of colour which attend the transition from
red or purple to black. This colour, and various shades
connected with it, have been regarded by some distinguished
foreign pathologists as evidences of the existence of chronic
inflammation, I would rather regard them as proofs that in-
flammation had subsided. Though it is not my intention
to pursue this pathological subject further in this volume,
I wish to correct an error into which I have been led, in re-
presenting this black pigment as a frequent occurrence in
the spleen. Though I made this statement in consequence
of my own personal observation in dissecting-rooms, the
numerous opportunities which I have since had of the
inspection of recent subjects, have convinced me that,
except to a limited and partial extent, the deposition
of this pigment in the spleen, is by no means common.
Although I retain unchanged the opinion, that the black
matter of the lungs is generally produced in the system
itself by the alteration of the blood, in opposition to
APPENDIX. 413
the view of Dr. Pierson, who ascribed it to inhaled car-
bonaceous matter, I cannot omit to notice a fact which
has been since observed by my friend. Dr. Gregory of Edin-
burgh. He found the lungs of a patient, who had been long
engaged as a coal-miner, unusually loaded with black mat-
ter. A specimen of this matter was subjected to a careful
analysis by Dr. Christison, the result of which rendered it
almost certain, that the black matter was in part, at least,
composed of minute particles of coal.
Page 380. That the circulation of the blood is promoted
by the way in which it is disposed of in the extreme vessels,
is a view which I am still disposed to entertain. It seems
to receive the support of analogy from the observations of
Dutrochet, respecting the motion of the sap in the roots,
and branches of vegetables.
414 APPENDIX.
OF THE PHENOMENA TO WHICH THE NAMES ENDOSMOSIS
AND EXOSMOSIS HAVE BEEN GIVEN BY H. DUTROCHET.
Since the publication of some of the preceding views re-
specting transudation and inhibition by Magendie and Fo-
dera, the subject has been very carefully investigated by
Dutrochet, who, in examining the transmission of dif-
ferent fluids through different kinds of thin and slightly
porous septa, has thrown much light on the phenomena
attending this transmission, and exhibited what appears
to him to be a new physical force distinct from ordinary
capillary attraction, electric agency, and hydrostatic pres-
sure ; to the movements resulting from this force, he gives
the names of endosmosis or exosmosis, according to the
direction.
Whether this force be altogether distinct and sui generis,
or a modification of some principle, with which we are
already partially acquainted, it seems to operate very
generally throughout living and dead, and organic as well
as inorganic matter, and as an agent intimately con-
nected with some vital phsenomena, it must not be wholly
passed over in this volume. If we take a membranous sac
or cavity, as for example, the ccecum of a fowl, or the air-
bladder of a fish, and having put a small quantity of fresh
milk into it, and secured the mouth by a ligature, we shall
find on immersing this sac in water, that in the course
of a few hours it will become quite full, and eventually
turgid. This turgidity is not permanent, and after a few
hours more have elapsed, the sac will again be flaccid.
If the sac be now opened, it will be found to contain
curdled and putrid milk ; if the sac be cleansed from
this offensive substance, and again partially filled with
APPENDIX. 415
milk and immersed in water, we shall find a repetition
of the phasnoinena, but the sac will neither become so
turgid nor so long remain full as in the first instance ;
this may be repeated several times, but with diminish-
ed effect. It does not make any sensible difference to
tiie experiment, whether the sac be inverted or not, or
whether the mucous or peritoneal coat be removed. If in-
stead of milk some other fluid be employed, similar phe-
nomena may be observed, but by no means in the same
degree in all; in fact, very striking differences may be
observed, depending on the nature of the fluids within and
without the sac, as well as upon the texture through which
they have to pass. All these points have been carefully
investigated by Dutrochet. In this enquiry, instead of a
fowl's ccecum, or fish's bladder, he employed an instru-
ment, to which he has given the name of an endosmometer,
which it will be necessary briefly to describe. It con-
sists of a cylindrical tube of glass, to which is fitted at
one extremity, a sort of moveable funnel, or cupola,
having such a rim, or lip, as will admit of a firm attach-
ment of the membrane, or other material, by which this
aperture is to be closed, and though the transmission of
endosmosis and exosmosis is to be examined, the other
extremity of the tube is left open, and a graduated scale is
applied to the tube itself : the fluid of which the power of
producing endosmosis is to be tried, is placed in the reservoir
formed by the closed funnel, after which the tube is applied
and the funnel immersed in water. If endosmosis take place,
the fluid will rise in the tube above the level of the water
surrounding the reservoir, and the amount of this elevation
may be read off from the graduated scale. In this way
Dutrochet discovered a very considerable difference in the
power of different fluids in inducing endosmosis, and it
appeared that in general this power was greater in dense
416 APPENDIX.
than in thin fluids. Solutions of sugar and of gum arabic
possessed this power in a very remarkable degree ; the for-
mer, when of the strength of one part sugar to three of
water, producing an elevation in a column of quicksilver of
258 millimeters, or 45 inches 9 lines, French ; and the
latter, when of the same strength, an elevation of more
than 28 inches. Saline and alkaline solutions have
also considerable endosmodic power. Dutrochet, at one
time, conceived that the acids were unfriendly to en-
dosmosis, or rather that they produced exosmosis, and he
was in consequence induced to attribute the phenomena
of this kind of transmission to electric, or galvanic
agency; and this opinion seemed to be strengthened by
the results of various experiments, which he instituted to
endeavour to ascertain the fact. Further experiments led
him to abandon the idea of electric agency, and he dis-
covered moreover, that most of the acids really possess
some power of producing endosmosis ; sulphuric acid how-
ever continued to form a marked exception.
Dutrochet likewise tried many of the animal fluids be-
sides milk, and he found that they also possessed con-
siderable energy in producing endosmosis, until, as in the
cases of the milk in the preceding experiments, they had
become putrescent. In this state he found that all the ani-
mal fluids were opposed to endosmosis. By varying his
experiments and employing other fluids free from animal
matter, but containing sulphurated hydrogen, as for ex-
ample, the hydro-sulphuret of ammonia, he discovered that
this principle, like sulphuric acid, is decidedly opposed to
endosmosis ; but he states, that we are at present com-
pletely ignorant of the mode in which these two principles,
the only known sedatives of endosmosis, act. In observing
the differences in the phenomena of endosmosis presented
by different fluids, there are two points to which Dutrochet
APPENDIX. 417
turns his attention, viz., the force and the rapidity of endos-
mosis, both of which may be made the subject of actual
measurement. The rapidity he appreciated by the number
of millemeters through which the fluid in the tube ascended
in successive hours. In order to estimate the strength, he
employs an endosmometer of a form somewhat different
from that before described. It is constituted on the same
principle as the apparatus by which Hales estimated the
force exerted in raising the sap of the vine. The reservoir
of this endosmometer is similar to that used in the former
experiments ; but the tube is bent so as to form a syphon
with its convexity upwards ; the descending leg of this
syphon fits one of the legs of another, which has its con-
vexity downwards. Mercury is put into this second syphon,
and the force of endosmosis being exerted on the quick-
silver in one leg, produces a corresponding elevation on the
mercury in the other, when it may be read off on a gra-
duated scale. By trying the rapidity and force of endos-
mosis on different fluids, by the use of these instruments,
Dutrochet found, as might have been anticipated, that
those fluids which acted with the greatest rapidity, likewise
acted with the greatest force ; and he also found, that the
power of endosmosis, in these two respects, increased with
the specific gravity of the fluids; provided that we estimate
this only by its excess above the specific gravity of water.
The following are some of the most remarkable differ-
ences depending on the nature of the substance through
which the transmission takes place. It may be seen from
the experiments performed on milk, and the intestines of a
fowl, that at each successive repetition of the experiment
with fresh milk, but the same portion of intestine, the
amount of endosmosis continued progressively to decrease :
this appeared to depend upon decomposition taking place in
the membranes themselves, by which they became infil-
E E
418
APPENDIX.
trated with a fluid, containing one of the principles which
has been already remarked to be negative of endosmosis.
Conducted by this fact, Dutrochet was led to the ob-
servation, that the transmission of fluid through a septum,
by the influence of endosmosis, was very materially in-
fluenced by the fluid with which it happened to be per-
vaded. When the septum was dry, and the pores conse-
quently filled with air, endosmosis was obstructed. This
obstruction was removed as soon as the septum was satu-
rated with water, and it became greatly increased, when,
instead of water, a fluid favourable to endosmosis, such as
a solution of sugar, or gum, occupied the pores of the sep-
tum. Various materials, besides the membranous parts of
animals and vegetables, were employed to close the funnel
of the endosmometer, such as very thin plates of sand-stone,
plaster of Paris, lime-stone, burnt slate, and the biscuit of
earthenware ; with some of these substances, the endos-
mosis was carried on with considerable energy, whilst with
others, it seemed totally inactive: this evidently did not
depend on the mere porosity of the material employed, and
satisfactorily showed that the phsenomena of endosmosis
must not be confounded with capillary attraction ; very
little, if any, endosmosis was observed to take place through
plates of sand-stone, whether the most porous, or the least
porous were employed, but the presence of a little ferrugi-
nous matter in one of the specimens was observed to favour
it. To ascertain, that in instances in which endosmosis
took place, there did not exist a physical impediment to the
transmission of fluids, Dutrochet tried them both with the
pressure of a column of fluid, and with the galvanic cur-
rent, and in these cases he observed transmission to take
place. The septa of lime-stone, though sufficiently porous
to allow the passage of fluids and to exert a capillary attrac-
tion upon them, were found to be extremely unfriendly to
APPENDIX. 419
endosmosis ; but those of burnt slate, and baked clays,
though but little promising, were observed to exhibit,
endosmosis, strongly.
In some of these experiments it was remarked, that after
the endosmosis had been carried on with considerable ac-
tivity in several trials with the same septum, a diminution
in the transmission took place, indicating that some impe-
diment had interposed itself; this was discovered to pro-
ceed from an accumulation of the gum, sugar, or other
principle in solution upon the surface of the plate or sep-
tum.
As respects the fluid, in which the reservoir of the endos-
mometer is immersed, it would seem, that there is no fluid
more favourable to endosmosis, and at the same time so con-
venient for experiment, as pure water. The examination
of this fluid, after it had been for some time employed,
afforded convincing evidence of a very curious fact. Not-
withstanding the copious and forcible transmission of
water through the septum, occasioning in some instances
an elevation of several inches in the tube, there is likewise,
at the same time, a transmission of fluid in an opposite direc-
tion ; thus, if a solution of muriate of soda be employed in
the endosmometer, it will not be long before traces of this
salt will be found in the water surrounding the reservoir of
the instrument.
Dutrochet has been remarkably ingenious and happy in
the application which he has made of the principle of en-
dosmosis and exosmosis, to the explanation of many cu-
rious points of vegetable physiology. The cause of the
motion of the sap, which has led to so much interesting
investigation and controversy, he attributes, in a great mea-
sure, to a structure situated near the junction of the root
and the stalk, in the minute cells of which, a powerful en-
dosmosis is exerted. The peculiar firmness which forms so
e e2
420 APPENDIX.
striking a distinctive character between a fresh and a living-
leaf, or other vegetable tissue, and the permanent flaccidity
of that which is dead, he designates by the term turgid
state, and refers it to endosmosis fillino; the cells of the ve-
getable structure, and induced by the nature of the fluid in
these cells. Hence, a faded, but still living plant, is rapidly
restored by i mmersion in water, and this experiment may
be repeated until the death of the plant, has allowed such an
alteration of the fluid remaining in the cells, that endosmo-
sis is no longer provoked. Even when this condition has
been arrived at, Dutrochet has succeeded in procuring an
artificial turgid state, by causing the cells to imbibe solu-
tions favourable to endosmosis. The forcible ejection of the
juice from the fruit of the elaterium is referred, by Dutro-
chet, to the progressive operation of endosmosis, in con-
junction with a peculiar arrangement of the cells, of which
the substance of the fruit is composed. Many curious spe-
culations have been formed respecting the cause which de-
termines the direction of the roots and the stalks of plants.
That which has been offered by Dutrochet, is, perhaps,
the happiest application of endosmosis, which he has yet
pointed out. From a difference in the arrangement of the
cellular structure in the stalks and the roots, it seems to
follow as an inevitable consequence, that the turgid state
induced by endosmosis, will cause the first to form a curl
with its concavity upwards, and the latter with its concavity
downwards, until the one has acquired an ascending, and
the other a descending direction.
Dutrochet thinks, that the same principle of motion
may be applied to the explanation of the curious phe-
nomena presented by the balsamina impatietis, the hcedysarum
mrans, and the mimosa pudica ; but in the movements of
this last especially, we are at fault for another yet unex-
plained power by which the movements are called into
APPENDIX. 421
play, even supposing that endosmosis is, in some way, im-
mediately concerned in producing the temporary turgidity
of the cellular organs, placed at the angles formed by the
moving joints of the plant. But if, as Dutrochet very can-
didly admits, something be wanted in the explanation of
the movements of the sensitive plant, this difficulty is much
more strongly felt in the movements performed by animal
life. Their nature and rapidity seem completely at va-
riance with any explanation founded on endosmosis ; they
are opposed by the experiments of Blanc, Burzoletti and Pre-
vost, and Dumas, upon muscles in action, and by the most
careful and minute microscopic observation of the elemen-
tary fibre, in which nothing approaching to the vesicular,
or cellular structure, imagined by Dutrochet, can be dis-
covered.
I am far from believing, that endosmosis and exos-
mosis, are not actively concerned in many of the phe-
nomena of animal life ; but in applying them, we must be
extremely careful not to ascribe too much to them, to the
neglect of other forces, which nature employs in living ani-
mals to restrain and modify their influence. I have had
occasion to notice a similar error into which, I apprehend,
both Magendie and Fodera have been led, with reference
to the phasnomena of transudation and imbibition. It is
doubtless extremely difficult to decide, how much may cor-
rectly be attributed to any of the different forces which take
a part in the various and complicated operations of animal
life, and it is only as a conjecture, that I notice the following
instances, in which it seems probable, that the principle
pointed out by Dutrochet may be concerned. When we
consider the great increase in the quantity of urine, which
takes place in conjunction with the production of sugar, in
those who are labouring under diabetes, and consider the
strong power of endosmosis, which Dutrochet ascribes to
422
APPENDIX.
sugar, may we not attribute the accumulation of a part of
the superabundant fluid to this cause, and even suspect,
that not in the kidneys alone, but throughout the urinary
apparatus, endosmosis may add to the bulk of secreted
urine? This idea, as respects the bladder at least, has,
prior to the publication of Dutrochet's views, had the
sanction of some distinguished physiologists, who have con-
tended, that even in the healthy state, much of the fluid
passed from the bladder is so collected.
Some proof that the excessive quantity of the secreted
urine is influenced by the presence of sugar, is afforded
by the fact, that if by strict exclusion of vegetable matter,
the production of sugar may be suspended for a time, the
quantity of fluid evacuated will exhibit a corresponding
diminution, notwithstanding that the disposition to the
complaint remains unabated. Another instance in which
the operation of endosmosis will, perhaps, be more readily
admitted, since the structures concerned are adventitious,
and, consequently, less perfectly organized, is furnished
by the enormous cysts, which are not unfrequently formed
in or near to the ovaries, constituting what is generally
called, ovarian dropsy. As these cysts are furnished with
no special glandular apparatus, it is not unreasonable to
refer the production of the fluid which they contain, to the
whole internal surface ; although, for reasons which I have
endeavoured to explain in a short essay on the anatomical
character of some adventitious structures, and which, I
need not here repeat, it is very probable that the produc-
tion of fluid is not equally rapid from every part. The
short space of time in which some of the largest of these
sacs are refilled, after the operation of paracentesis, is no
less remarkable than the character of the fluid so produced.
It is well known that these fluids are copiously charged
with a muco-albuminous substance, which, like sugar, must,
APPENDIX. 423
on Dutrochet's principles, be greatly favourable to endos-
mosis.
If endosmosis be admitted to take a part in those func-
tions, in which there is a high degree of life and organiza-
tion, it must be admitted, a fortiori, in other instances, in
which organization is greatly inferior, and life nearly or
quite extinct. Hence, I apprehend, we may be allowed to
have recourse to its assistance to explain the changes which
take place in structures which appear to be devoid of or-
ganization, or which having lost the life and organization
which they once possessed, are yet still retained in the
system. The copious impregnation of such substances
with earthy salts, constituting what are termed petrefac-
tions, examples of which are met with in old tubercles of the
lungs, in the mesenteric glands, in the coats of arteries,
and in various other situations, may, I believe, be referred
to this principle.
424 APPENDIX.
ON THE MICROSCOPIC CHARACTERS OF SOME OF THE
ANIMAL FLUIDS AND TISSUES. BY J. J. LISTER AND
DR. HODGKIN.
The researches of Prevost and Dumas, respecting the
microscopic appearances of the blood, are alluded to in the
work of Dr. Edwards. The very superior compound achro-
matic microscopes of my friend J. J. Lister, who has devoted
much of his leisure time to the cultivation of this branch of
optics, have enabled him and myself to correct some of
the illusions into which the indefatigable physiologists of
Geneva, to whom I have alluded, were unwittingly led by
the imperfection of their instruments. Hence, it appears,
that there would be an obvious advantage in reprinting in
this work, with some few additions, the observations which
have already been published in the Annals of Philosophy,
and in the Catalogue to the Anatomical Museum of Guy's
Hospital.
Any approaches towards a more accurate knowledge of
the intimate structure of organized beings, may reasonably
be looked to as collateral aids to our acquaintance with the
influence of physical agents on life.
Very soon after the invention of the microscope, it was
ascertained, that the blood, instead of being homogeneous,
consisted of a fluid with coloured particles suspended in it.
This discovery is attributed to Malpighi ; but it does not
appear that his inquiries into this subject were pushed to
any great extent.
APPENDIX. 425
Observations similar in their result, but far more numerous
and minute, were made nearly at the same time by Lewen-
hoeck, apparently without any connexion with those of Mal-
pighi.
This indefatigable Micographer, describes the coloured
particles of the blood as circular, or spherical, while at rest,
but elliptical when in motion. Those of fish, he states to
be flat and elliptical ; and he remarked, that in the fluids
of some insects, the particles were of a green colour. He
believed rather than demonstrated, that each globule of the
blood was composed of six subordinate globules.
For a considerable time the opinions of Lewenhoeck
were generally received, and physiologists and micographers,
amongst whom we may notice Fontana, taught that the
particles of the blood were globular.
Haller in one part of his works concurs in this opinion,
but doubts their form being susceptible of change from mo-
tion. In another place, he describes the red particles of
the blood as flattened, and compares them to lentils.
Senac has taken the same view of them.
De la Torre, who employed in his observations single
globules of glass possessed of very high power, but defec-
tive in point of clearness, recognized the flattened form of
the particles, but mistaking the shaded spot in their centres
for a perforation, he described them as rings. He believed
them to be jointed, and to break regularly into seven
pieces.
De la Torre was soon followed by Hewson, who, together
with improved instruments, brought a large stock of inge-
nuity and perseverance into the inquiry.
To obviate the confused view, which the large proportion
of the particles in undiluted blood is very apt to produce,
he introduced the plan of mixing it with fresh serum,
426 APPENDIX.
being well aware of the change of form produced by the
addition of water.
He states that if, after this change is effected, a drop
or two of a neutral solution be added before the burst-
ing of the vesicles, the flat figure will be restored.
He found no central particles in the blood of the splenic
vein.
Without entering into the numerous and in many respects
accurate observations of Hewson, since we shall have occa-
sion to refer to them in a subsequent part of this paper, it
will be sufficient to recall to memory the results which he
drew, as to the nature and figure of the particles.
He satisfactorily shewed that they are not globular, but
flattened, as well when circulating in the vessels of the living
animal, as when drawn from the body ; and he also proved
the fallacy of De la Torre's views with respect to a central
perforation.
He believed the dark central spot to be a solid particle,
contained in a flat red vesicle, whose middle only it occu-
pied, and whose edges were hollow and either empty, or filled
with a subtile fluid. He observed the flattened vesicles
to become spherical, by the addition of water, and at the
same time to be contracted in their diameters.
He states, that the middle particle may be seen to fall from
side to side in the hollow vesicle like a pea in a bladder, or
sometimes to stick to one part of the vesicle. The middle
particles are less easily soluble than the flat vesicles which
contain them, and a little time after the proper quantity of
water being added they disappear, leaving the middle par-
ticles which appear to be very small.
He states them to be larger in the immature young, than
in the perfect animal.
He likewise observed them to be of the same form, when
APPENDIX, 427
circulating in the vessels during life, as when escaped from
them, and denies that they alter from resistance during cir-
culation.
This view of the structure of the particles, was founded
on the examination of the blood of the skate of the larger
size, and elongated form, of which he was perfectly aware-
He admits, that it is more difficult to gain a sight of these
appearances in the blood of man, but tells us that he had,
notwithstanding, distinctly done so with the help of bright
and clear day-light.
Falcon ar, by whom Hewson's Observations were repeated
and published ; and also Dr. Wells, entertained similar
views respecting the figure of the particles of the blood.
Cavallo believed, that they consisted of double spheres.
The concise but pertinent observations of Dr. Young,
claim particular attention and respect. The particles of
the blood of the skate, from their superior size, are con-
sidered by him, as they had been by Hewson, as the best
suited for the commencement of the investigation.
He describes them as exhibiting an oval and flattened
form, and containing a nucleus generally round, but some-
times a little irregular, which occupies a nearly permanent
position in the centre of the particle. It often remains
distinctly visible, while the oval part is scarcely perceptible,
and as the portion of blood dries, becomes evidently pro-
minent. This nucleus is about the size of an entire par-
ticle of the human blood, the whole oval being about twice
as wide, and not quite three times as long. The nucleus
is very transparent, and forms a distinct image of any large
object which intercepts a part of the light by which it is
seen, but exhibits no inequalities of light and shade that
could lead to any mistake respecting its form.
Having given these remarks respecting the particles in
the blood of the skate, he proceeds to those of human blood,
428
APPENDIX.
of which he says, that if placed under similar circumstances
in the field of the microscope, near the confine of light and
shade ; although they are little if at all less transparent,
one immediately sees on the disk an annular shade, which
is most marked on the side of the centre on which the mar-
ginal part appears the brightest, and consequently, indi-
cates a depression in the centre ; but the Doctor was not
quite decided, whether this apparent depression might not
depend on some internal variation in the respective density
of the particle. He thought the axes about ^ or \ of the
diameters, but the particles never appeared to him to be " as
flat as a guinea." He never observed a prominence on the
outline of the particles of human blood, but he remarked,
that when they had been kept for some time in water, and a
little solution of salt was added, their form and structure are
more easily examined, and that they appear to resemble a
soft substance with a denser nucleus, not altogether unlike
the crystalline lens with the vitreous humour as seen from
behind ; but with respect to a central particle detached
within a vesicle, like a pea in a bladder, he is satisfied that
Hewson was completely mistaken. The colouring matter,
according to the Doctor's view, does not appear to be a
mere superficial layer, but imbues the substance of the par-
ticle from which water extracts it, and occasions such a
loss of specific gravity that they remain suspended instead of
sinking in that fluid. In this state they easily escape ob-
servation, which circumstance, together with their passage
through filtering paper, has led to the monstrous assertion
that they are soluble in water. When they have been long-
kept in water, and even after putrefaction has taken place,
they do not appear to become constituent parts of an homo-
geneous fluid.
In the memoirs of Sir E. Home and Bauer relating to
APPENDIX. 429
the subject before us, we find the globular figure of the
blood again maintained.
The colouring matter appeared to them not to be con-
tained in the particles, but rather to envelop them. They
describe it as separating very readily, and flowing from all
parts at the same instant. " To examine them," say they,
" in their coloured state, a very small quantity of blood must
be examined at once, and this must be spread as thinly as
possible that the moisture may instantly evaporate, they
then remain of their full size and colour, perfectly spherical.
They seem to consider the flattened form as the effect of
a change which takes place after death ; for Bauer observes,
in opposition to the assertion of Hewson, that in the skate,
the particles during life are of the form of an egg, but that
almost immediately after death they are flattened.
If the quantity of blood under examination be sufficiently
large to retain its moisture only half a minute, the colour-
ing matter in a few seconds begins to separate and form a
circle round the globules. If the blood be diluted with
water, the separation is instantaneous. They give the
diameter of the globule, enveloped in its colouring matter,
as pjVo, and when deprived of it, as ^Vo- Elsewhere
they state the proportion of the colouring matter to the
globule to be as three to one. They describe the globules,
when separated from the colouring matter, as being mu-
tually attracted and coalescing with some disposition to
linear arrangement, which is not the case so long as the
coloured envelope remains attached ; they further describe
globules in pus, in muscular fibre, and in the substance of
the brain, identical in point of size with the uncoloured
globules of the blood.
The more recent and extended researches of Prevost and
Dumas tend in some respects to confirm the opinions of
430
APPENDIX.
Hewson, while in others they more nearly coincide with
those of Sir E. Home and Bauer.
They represent the particles of the blood as circular in all
the mammalia, and elliptical in birds, reptiles, and fishes,
but flattened in all, though a little prominent at the cen-
tre. Their size is uniform in the same animal, but differs
in different species, from -^j of a millimetre in the salaman-
der, to j^q in the callitriche, or -gj^ m the goat. They
regard them as consisting of a central colourless globule
of one uniform size, -^-g of a millimetre, in all classes of
animals, like those of chyle, milk, and pus, and inclosed,
as before stated by Hewson, in a coloured membraneous
vesicle, on which depends the difference in the form and
size of the particles.
In those animals whose blood has elliptical particles, the
nucleus appears also elliptical until muriatic acid is added,
by which they conclude, that the surrounding matter is dis-
solved and removed. The nucleus has then the same ap-
pearance as that of the mammifera.
By repeated examination of the blood whilst in the
course of circulation, these physiologists satisfied them-
selves that the particles possess the same size and form
whilst in the vessels, as they do when recently drawn from
the body. They deny that they perform a movement of
rotation on the centres ; but in describing the effect pro-
duced on the form of the particles from occasional resistance
which they meet with, they confirm the remark of Lewen-
hoeck as to the elongation of the particles during circula-
tion.
In our examination of the particles of the blood, we
have in vain looked for the globular form attributed to
them, not only by the older authors, Leeuwenhoeck, Fon-
tana, and Haller, but still more recently by Sir Everard
Home and Bauer. Our observations are also at variance
APPENDIX. 431
with the opinion long since formed by Hewson, that these
particles consisted of a central globule inclosed in a vesicle
composed of the coloured part, and which, though refuted
by Dr. Young, has since, in a modified form, been revived
by Sir Everard Home and Bauer in this country, and by
Prevost and Dumas on the Continent. We have never
been able to perceive the separation of the colouring matter,
which our countrymen have described as taking place in a
few seconds after the particles have escaped from the body ;
nor can we with Prevost and Dumas, consider the particles
as prominent in the centre.
The particles of the blood must unquestionably be classed
amongst the objects most difficult to examine with the
microscope ; partly from the variations of form to which
their yielding structure renders them liable, but still more
from their being transparent and composed of a substance
which, as Dr. Young has remarked, is probably not uniform
in its refractive power.
These causes of error we have endeavoured to counteract
by varying the mode of observation. We have viewed the
particles both wet and dry, both as opaque and as transpa-
rent objects, under great varieties of power and light, and we
lay no stress on observations which have not been confirmed
by frequent repetition.
To us the particles of human blood appear to consist of
circular flattened transparent cakes, which, when seen
singly, appear to be nearly or quite colourless. Their edges
are rounded, and being the thickest part, occasion a depres-
sion in the middle, which exists on both surfaces. This
form perfectly agrees with the accurate observations of Dr.
Young, that on the disks of the particles there is an annular
shade, which is darkest on that side of the centre on which
the margin is brightest. Though the Doctor drew the
obvious conclusion that the disks were concave, he does not
432
APPENDIX.
consider the fact as demonstrated ; since the appearance
might be produced by a difference in the refractive power
of different parts of the corpuscle.
This objection we think completely met;
1st. By their transmitting the erect image of any opaque
body placed between them and the light, precisely as a
concave lens would do.
2dly. By the appearance presented by the particles when
viewed dry, as opaque bodies. When illuminated by the
whole of a Leiberkuhn, the entire margin is enlightened,
and in most of the particles there is besides a broad inner
ring of considerable brightness ; whilst the centre, and the
space between the two rings, is completely dark. On half
the Leiberkuhn being covered, the rings are reduced to
semicircles, the outer one being opposite to the light side,
and the inner to the darkened side of the speculum.
3dly. When fluid blood having been placed between two
slips of glass, a single particle happens to be at right angles
to the surfaces of the glass, so as to be seen in profile, the
two concave surfaces are visible at the same time,* or alter-
nately, but more distinctly, if the particle slightly va-
cillates.
The concavity of the disks is, however, extremely trifling ;
and under particular circumstances, in a few of the particles,
the surface is to all appearance quite flat.
Notwithstanding the great uniformity in the size of the
particles of the blood, so long as they retain, unimpaired,
the form which they possess on escaping from the body,
their real magnitude has been so variously estimated, that
we judged it worth while to attempt a new measurement.
In doing so, we adopted a method somewhat different from
* This happens notwithstanding the interposition of the edge, when the centre
of the particle is accurately in focus, owing to the large pencil of light admitted
by the object glass.
APPENDIX. 433
those hitherto employed. A camera lucida is adapted to
the eye-piece of the microscope in such a manner that the
distance of the paper being ascertained, the object may
be drawn on a known scale. Tracings of several of the
images being made, they were applied to, and compared
with, the images of other particles until their accuracy was
established.
The diameter of the particles obtained in this manner
may be pretty correctly stated at -g-^o o °f an inch.
The following measurements by former observers are
given for the sake of comparison.
Jurine T^
Jurine in a 2d measurement . . -a 9l^
Bauer v ^o
Wollaston ^oVo^
Young -gfa o
Kater To'o o
Ditto ToV o
Prevost and Dumas ToV6
The thickness of the particles, which is perhaps not so uni-
form as the diameter of the disks, is on an average to this
latter dimension as 1 to 4.5
The form and size of the particles of the blood of other
animals have frequently been compared with those of man.
Many observations were made for this purpose by Hewson ;
but while some of them appear tolerably accurate, others are
decidedly far from the truth. Those which have recently
been made by Prevost and Dumas, are the most extensive
and complete which as yet exist. Our attention having
been chiefly taken up with the blood of man, we have not
as yet carried our investigation of that of other animals so
far as we design doing; we have, however, examined the
F F
434 APPENDIX.
blood in all the classes of vertebrated animals, and in dif-
ferent species of most of them. Our observations com-
pletely accord with those of Prevost and Dumas, as to the
particles having a circular form in the mammalia, and an
elliptical one in the other three classes. There are varieties
both in the size and proportion of the particles in idifferent
species. Thus for example, in the pig and rabbit, the par-
ticles have a less diameter, but a greater thickness than in
man. We have hitherto invariably found the elliptical
particles larger than the circular, but they are propor-
tionably thinner. In birds, the particles are much more
numerous, but smaller than in either reptiles or fishes.
There are numerous interesting phenomena which pre-
sent themselves when the particles lose their integrity and
assume new forms. Changes of this description are occa-
sioned by the spontaneous decomposition which the blood
undergoes a longer or shorter time after its escape from the
body, by mechanical violence, and by the addition of va-
rious substances, which appear to exert a chemical action
on the matter of which the particles are composed. To
these appearances we have been induced to devote the more
attention, from their seeming calculated to throw some
light on the composition and structure of the particles.
We were also desirous of not hastily or rashly denying the
existence of those colourless central globules which have
been strongly insisted on by Sir Everard Home and Bauer,
and by Prevost and Dumas, and which have been regarded
not merely by themselves, but by other distinguished and
intelligent physiologists, as constituting by their varied
combination the different organic tissues. The separation
and detection of these globules is stated to be facilitated
by some of the means which effect the changes to which I
have alluded ; but, as I have already stated, we have in vain
looked for these globules.
APPENDIX. 435
After blood taken from the living body has been kept a
sufficient length of time for an alteration in the form of the
particles to commence, and this according to circumstances
will be from a very few hours to one or more days, the first
change which we have noticed is a notched or jagged ap-
pearance of the edge of a few of the particles. The number
so modified continues to increase : some of the particles lose
their flattened form, and appear to be contracted into a
more compact figure ; but their outline continues to appear
irregular and notched, and their surfaces seem mammillated.
Hewson and Falconar appear to have accurately noticed
this change, and have compared the particles in this state
to little mulberries. When more time has elapsed, most
of the particles lose this irregularity of surface and assume
a more or less perfectly globular form, and reflect the image
of an interposed opaque body as a convex lens would do.
Some of the particles resist these changes much more obsti-
nately than others.
If a small quantity of blood be placed between two
pieces of glass, which are afterwards pressed together with
some force, several of the particles, however recent the
blood, will be materially altered. The smooth circular
outline is lost, and as in the former case, they appear
notched. A few seem to be considerably extended by the
compression. When the surface of the particles has in this
way been broken into, the ruptured part exhibits an adhe-
sive property capable of gluing it to another particle or to
the surface of the glass ; but the particles in their natural
state, seem to be nearly void of adhesiveness.
There is scarcely any fluid except serum which can be
mixed with the blood without more or less altering the form
of its particles, probably in consequence of some chemical
change. In this general result our observations accord
with those of Hewson and Falconar, whose experiments of
f f 2
436
ATPENDIX.
this kind were very numerous. We differ from them, how-
ever, in a few particulars. There is no fluid which, when
mixed with the blood, produces a more remarkable and sud-
den alteration in the appearance of the particles than water
does. With a rapidity which, in spite of every precaution,
the eye almost invariably in vain attempts to follow, they
change their flattened for a globular form, which from the
brightness and distinctness of the images which they reflect
as convex lenses, must be nearly perfect.
Contrary to Sir Everard Home's remark, that the par-
ticles in their perfect and entire state are not disposed to
arrangement, it is in this state only that we have found
them run into combinations, which they assume with con-
siderable regularity. In order to observe this tendency of
the particles, a small quantity of blood should be placed
between two slips of glass. In this way the attraction
exerted by one of the pieces of glass, counteracts that of
the other, and the mutual action of the particles on each
other is not interfered with, as is necessarily the case when
only one slip is employed.
When the blood of man, or of any other animal having
circular particles, is examined in this manner, considerable
agitation is at first seen to take place amongst the particles ;
but as this subsides they apply themselves to each other
by their broad surfaces, and form piles or rouleaux which
are sometimes of considerable length. These rouleaux often
again combine amongst themselves, the end of one being
attached to the side of another, producing at times very
curious ramifications.
When blood containing elliptical particles is examined in
the same manner, it exhibits a not less remarkable but very
different mode of arrangement. Though they are applied
to each other by some part of their broad sides, they are
not so completely matched one to another, as is the case
APPENDIX. 437
with circular particles; and instead of placing themselves
at right angles to the glass, with their edges presented to
its surface, they are generally seen nearly parallel to it, one
particle partially overlaying another, and their long di-
ameters being nearly in the same line. In the blood of the
toad or frog the lines thus formed are subjected to a kind of
secondary combination, in which several assume to them-
selves a common centre, whence they diverge in radii. It
is by no means rare to see several of these foci in the field
of the microscope at one time. The particles at these points
appear crowded, confused, and misshapen. This tendency
to arrangement is perhaps not to be wholly attributed to the
ordinary attraction existing between the particles of matter,
but is probably to a greater or less degree dependent on life;
since we have not only observed that the aggregating energy
is of different force in the blood of different individuals, but
that in the blood of the same individual it becomes more
feeble the longer it has been removed from the body. At
the same time, we are very far from believing that these or
any other mode of aggregation which the particles of the
blood may be observed to assume, ought to be regarded as
at all analogous to the process which nature employs in the
formation of the different tissues.
I some years ago briefly stated this opinion, which I was
induced to form a priori* ; but I may now appeal to facts
in support of it.
Besides the particles above described, and which are
evidently very important and essential constituents of the
blood, other particles, much smaller and much less nu-
merous, may occasionally be observed in the blood. They
are circular, and perhaps globular, but we have not made
them the subject of much examination.
* See " Thesis de Absorbendi Functione." Edin. 1823 ; and this Vol. p. 377.
438 APPENDIX.
We have not made many observations with a view to
discover any microscopic differences between the blood of
healthy and diseased persons. We have in general seen
no perceptible difference between blood obtained from a
small puncture expressly for the purpose of observation,
and a portion of a larger quantity drawn from the arm to
relieve some affection requiring venesection. There is some
difference in the tendency of the particles to combine in
piles, or rouleaux, but of the cause of this, we can suggest
no explanation. The absence of this disposition to com-
bination was most remarkable, and indeed almost com-
plete, in a small quantity of blood taken from the arm of
a young woman labouring under strongly marked chlorosis.
This blood coagulated with little or no contraction of the
crassamentum, which was covered with a thin buffy coat of
a remarkable colour, somewhat resembling weak coffee
diluted with milk.
The striking appearance in the blood of patients affected
with cholera, has recently rendered its examination an ob-
ject of some interest. In a specimen of this blood, furnished
me from the City Cholera Hospital, by my friend Alexander
Tweedie, the particles possessed their form, and other cha-
racters completely unaltered, notwithstanding that the
blood had unavoidably been drawn a few hours before the
examination was made.
We have observed in the blood of some individuals, that
several of the particles presented more or less of the
notched or jagged appearance, in which they have been
compared to mulberries, and which may be regarded as a
symptom of decay, or disintegration ; since, as has been
already remarked, it is seen to take place after the blood
has been for a considerable time removed from the body.
In the instances to which I am now alluding, the blood
was quite recent, and taken from tolerably healthy sub-
APPENDIX. 439
jects. In the blood of a small dog, from which the spleen
had been removed several weeks, and which appeared to
be in an emaciated sickly state, the particles generally-
seemed to have lost their natural figure, and to have been
somewhat reduced in size. They likewise bore an un-
usually small proportion to, the watery serum in which they
were suspended. In the blood of a remarkably fine doe
rabbit, from which the spleen had been removed some
years before by my friend Dr. Blundell, the particles
did not seem quite so clear and regular in their figure, as
in the blood of another rabbit examined at the same time
for the sake of comparison. We are far from inferring
from these two observations, that the particles of the
blood are formed in the spleen, as Hewson imagined.
In the first instance, their altered form may well be as-
cribed to the peculiarly sickly state of the dog; and in
the doe, it might in part be occasioned by the state of
oestrum in which she happened to be. It would be highly
interesting to discover where and in what manner the par-
ticles of the blood are produced. When we consider their
great uniformity as to size and figure in each species of ani-
mals, and the undeviating precision with which the rule
is observed regarding their elongated figure in oviparous ani-
mals, and their circular form in those which are viviparous,
we cannot help admitting some simple, but very powerful
cause. We might hope to obtain some light on this sub-
ject, from the examination of the blood of a chick shortly
after incubation had commenced. The presence of red
blood is very distinct in the small areola of vessels belong-
ing to the membrane of the yolk, immediately around the
punctum saliens, whilst as yet, the rudiment of the spine
and head, with a faint trace of the eye, and a very imper-
fect heart, are but just perceptible. In the very recent
blood, seen whilst in motion in these minute vessels, the
440
APPENDIX,
particles seem to want that uniformity as to size and figure,
which is so striking in the more advanced animal ; yet it
appeared, that they already exhibited a tendency to the
elongated figure. This enquiry is one which we by no means
consider as complete, but it induced a doubt in our minds,
as to the accuracy of the remark of Prevost and Dumas,
that the particles in the blood of an incubated egg, are of
a circular figure, as in the mammalia, until the period when
the existence of the liver becomes apparent. In very
minute animals quite of the lower classes, in which the
vascular system is neither extensive nor complicated, and
in which the channels for the conveyance of the nutrient
fluid are proportionably of large diameter, the particles are
not only comparatively rare, but very irregular as to size
and figure, and even in colour. Although we hardly feel
ourselves warranted in admitting a conjecture as to the
mode of formation of these particles, yet we cannot help
suspecting that they are much more intimately connected
with their motion during circulation, than with any par-
ticular organ specially devoted to their production.
The striking changes effected in the particles of the blood,
by the addition of water and other fluids, seems to merit care-
ful attention at the present period, when the copious dilu-
tion of the blood is had recourse to, with the hope of coun-
teracting the formidable symptoms of cholera. The great, sud-
den, and general alteration, caused by the mixture of pure
water, would seem to render this fluid one of those which
are the most to be dreaded. Saline solutions, on the con-
trary, have the recommendation of producing very little
alteration of figure in the particles.
Chyle. — We have as yet devoted very little time to the
microscopic examination of this fluid. A specimen taken
from the thoracic duct of a young dog, a short time after his
eating a hearty meal, was of a tolerably good white colour
APPENDIX. 441
when first drawn, but it rapidly acquired a light pink blush
on the surface by exposure to the air. It also speedily
coagulated, but the quantity obtained was too small to
admit of a sensible separation of serum. A small quantity
of this chyle placed between too slips of glass, as in the
examination of the blood, exhibited an infinite number of
extremely minute particles in a state of constant agitation.
From these two circumstances, it appeared impossible
to form any precise and satisfactory idea of their figure, but
they appeared pretty uniform as to size. Dilution with
water and with saline acid and alkaline solutions had no
sensible effect in rendering the particles more distinct; but
it is worthy of remark, that wmilst the solution of oxymu-
riate of potash manifestly heightened the pink hue pro-
duced by exposure to the air, both the acid and alkaline
solutions discharged it, a fact which it may be well to con-
sider in connexion with the observations of Dr. Stevens. A
minute portion carefully obtained from one of the lacteals,
before it had passed through a lymphatic gland, presented
precisely the same microscopic characters as that obtained
from the thoracic duct. It is to be observed, that the
microscopic characters of the chyle bear no resemblance
to those of milk, of which we are next to speak.
Milk. — In this fluid the particles appear to be perfect and
very transparent globules. But, far from being uniform,
they present the most remarkable varieties in respect to size.
Whilst some are more than double, others are not a tenth
part of the size of the particles of the blood, to which they
bear no resemblance.
Pus. — As far as we have yet examined this secretion, its
particles appear to be as irregular in size and figure as those
observed in the brain, and bear no resemblance to those of
the blood.
In proceeding to offer a very short sketch of the result of
442 APPENDIX.
our inquiries into the microscopic appearance of some of the
animal tissues, I do so with one painful feeling, which I
shall perhaps be excused from expressing. It is, that I am
under the necessity of differing from my excellent and intel-
ligent friend Dr. M. Edwards. It was the knowledge of
his talents and address, and of the patience and care with
which he made those investigations, which he has related,
which induced me to enter into the examination of a ques-
tion, which I had already regarded as settled in the nega-
tive. And though J. J. Lister and myself, in repeating the
observations of Dr. M. Edwards, have arrived at widely
different conclusions, I am confirmed in the conviction,
that he described what he saw, and that he only saw amiss
through the imperfection of his instruments. The idea of
the globular structure of the different tissues is however by
no means peculiar to Dr. Edwards, and to those micographers
to whom I have already frequently alluded. Dr. Edwards,
in the papers to which I refer, has employed much erudi-
tion to show that similar views had been taken, with respect
at least to some of the tissues, by Hooke, Leuwenhoeck,
Swammerdam, Stuart, Delia Torre, Prochaska, the Wenzels
Dutrochet, and Clocquet.
Muscle. — The muscular tissue may be easily seen with
the naked eye, or with the assistance of a comparatively
feeble lens, to be composed of bundles of fibres, held to-
gether by a loose and fine cellular membrane, and these
fibres are again seen to consist of more minute fibrillse. It
is difficult to push the mechanical division much further ;
for the softness of the muscular substance is such, that it
either crushes or breaks off, rather than admit of further
splitting. If a piece of one of the most delicate of the
fibrillse last arrived at be placed on a piece of glass in the
field of the microscope, lines may be seen parallel to the
direction of the fibre, which show a still further division
APPENDIX. 443
into fibres.* Although no trace of globular structure can
be detected, innumerable very minute, but clear and fine,
parallel lines or striae may be distinctly perceived, trans-
versely marking the fibrillar . In some instances they seem
to be continued nearly or quite at right angles completely
across the fibril ; but frequently the striae in one part are
opposite to the spaces in another, by which arrangement
a sort of reticulated appearance is produced. The striae
are not in all specimens equally distant, but this may per-
haps be owing to the elongation or contraction of the fibre.
We have discovered this peculiar and very beautiful ap-
pearance in the muscles of all animals which we have as
yet examined ; and as we have seen it in no other tissue,
we have been induced to view it as a distinguishing feature
of muscle.
Although this characteristic appearance may be unequi-
vocably seen in the voluntary muscles of the smallest ani-
mals of the lowest classes ; yet, with the exception of the
heart in most animals, and perhaps also, the gizzards of
graminivorous birds, we have been unable to detect it in any
muscle of organic life, such as, e. g. in the muscular coat
of the alimentary canal, and that of the bladder. We
have not only examined these textures in their ordinary
state, but also in many instances in which encreased
exertion, or other causes, had greatly developed their
power and bulk, as when the bladder has gained great
thickness and strength from diminution of the pervi-
ousness of the urethra, and the coats of the intestine
from stricture of the colon or rectum. This essential
difference between the minute structure of the muscles of
voluntary motion, and those of organic life, is not only suffi-
* When sufficiently moistened, either by their own juices or by the addition
of water, a minute portion of muscle thus thinly extended exhibits a nacreous
irridescence.
444 APPENDIX.
cient to warrant a more decided distinction between them,
anatomically and physiologically, but is borne out by equally
striking differences in the pathology of the two structures.
I must not, however, enter further into this subject on the
present occasion, pathology forming no part of the present
work. The nature and function of the substance of the
uterus has been made the subject of warm dispute: some
physiologists regarding it as unquestionably and powerfully
muscular, whilst others refuse it the title of muscle. It
was therefore an object of no little interest to us, to avail
ourselves of an opportunity of examining this structure in
its state of extreme development at the full period of utero-
gestation. We could not detect in it the slightest traces
of that appearance which we feel warranted in regarding
as universally and essentially belonging to true muscle.
We could perceive no sensible difference between its fibres,
and those of the middle coat of the bladder, but so far
as we are warranted in speaking of the muscular coat of
the bladder and intestines, are we strictly correct in attri-
buting muscularity to the uterus. In fact, this organ in
its state of complete development forms the most striking
and powerful example of this distinct contractile tissue,
which, in accordance to the views of Professor Blainville,
we may regard as an appendage to the mucous membranes.
The minute fibrillse, which enter into the composition of
the fasciculi of fibres, of which this tissue is made up, in-
stead of presenting the transverse striae, of which we have
been speaking, are perfectly smooth. They appear to be
continued to a considerable length of nearly uniform width.
In some instances these fibres are nearly straight and pa-
rallel, whilst in others there is more interlacing, and we are
not sure that the fibrillaa do not unite and divide amongst
themselves. In health they seem much less soft and fragile
than the fibres of voluntary muscles deprived of life, and
APPENDIX. 445
they are manifestly susceptible of considerable distention. In
some states of disease, however, these characters are com-
pletely changed. We have not been able to observe, either
in the voluntary muscles, or in those of organic life, any
confirmation of the ingenious theory of Prevost and Dumas,
already exhibited in the Appendix in this work ; in fact, the
subject of vital contractility appears to us to be as great a
mystery as ever. It might have been concluded, that the
beautiful transverse striae universally met with in all volun-
tary muscles, was, in some way, essential to this function ;
but their total absence in the fibres of the muscles of or-
ganic life, endowed with equally powerful and more ex-
tensive, though somewhat different contractility, throws
a strong doubt this supposition. The views of Dutro-
chet, who has beautifully explained some of the move-
ments of plants by the application of the principle of
exosmosis and endosmosis, which he has so carefully de-
veloped, do not seem from our observations to be applicable
to the muscular motions of animals. The remarkable move-
ments of the mimosa pudica, of the h&dysarum gyrans, and
of the bahamina impatiens, are by Dutrochet referred to
the turgid state of a specially constituted vesicular struc-
ture ; and he is disposed to attribute the muscular motion
of animals to a similar mechanism.
Arteries. — The middle coat of these vessels being still
regarded by some persons as muscular, we were desirous of
discovering whether its minute structure was at all more
favourable to such an opinion than its chemical composition.
Its subdivision may be carried as far as that of any tissue ;
and it evidently consists essentially of long, straight, very
delicate and even fibres, which offer no more trace of those
transverse striae, which we have regarded as the peculiar
characteristic of muscle, than they do of elementary glo-
bules.
446 APPENDIX.
The inner coat, when completely detached from other
structures, and presenting the appearance of a very thin
uniform and almost transparent membrane, is also, by the
aid of the microscope, seen to be composed of fibres, which
are extremely delicate, smooth and uniform, but very tor-
tuous and matted together, in the form of an intricate
plexus.
Nerves. — These appear to be essentially composed of
fibres, but their structure is looser than that of muscle.
Though the fibres of nerves do not form such intricate
plexuses as those of some other tissues, their course is by
no means straight. We have looked in vain for globules,
as well as for any trace of medullary matter, which has
been somewhat gratuitously supposed to be inclosed in the
nerves.
Cellular membrane. — This tissue, when perfectly formed,
appears to be composed of delicate fibres, assembled toge-
ther without any apparent order of arrangement. They
exhibit no more appearance of a chaplet, or string of glo-
bules, than any other of the animal tissues ; they have
nothing like the transverse striae which characterize the
fibrillse of the voluntary muscles, but like those of the in-
voluntary muscles and of nerves, present a smooth surface
and nearly uniform width, though they are much less dis-
tinct than either of the last mentioned tissues. The demon-
stration of the fibrous structure of the cellular membrane,
is opposed to the view which Meckel entertained respect-
this tissue, which he has regarded as amorphous, and of a
consistence approaching that of mucus, and only presenting
cells, lammellse and fibres, as the effect of the means which
are taken to examine it. The opinion, however, of Meckel
is not to be rejected as altogether void of foundation in
correct observation ; it is probably to be attributed to his
having taken as specimens for examination, portions in an
APPENDIX. 447
incomplete state, as they occur in newly formed false mem-
branes, which, when just separated from the serous fluid
which pervades them, present no determinate arrangement,
and in other respects more nearly approach to Meckel's
description.
Serous membranes. — The structure of these membranes,
bears the closest resemblance to that of the cellular.
Mucous membrane. — We have not been able to distinguish
any decided fibrillse, or other determinate form, in these
membranes; but our examination of this tissue has not
been completed.
Brain. — If there is any organized animal substance which
seems more likely than another to consist of globular parti-
cles, it is undoubtedly that of the brain. Our examination
of it has as yet been but slight ; but we have noticed that
when a portion of it, however fresh, is sufficiently extended
to allow of its being viewed in the microscope, we see in-
stead of globules a multitude of very small particles, which
are most irregular in shape and size, and are probably more
dependent on the disintegration than on the organization of
the substance.
The structure of some other parenchymatous parts ap-
pears equally indeterminate, presenting neither globule nor
fibre.
448 APPENDIX.
ON THE USES OF THE SPLEEN.
From the Edinburgh Medical and Surgical Journal, Jan. 1822.
[In reprinting the following juvenile essay, I must be al-
lowed to remark by way of apology, that the functions it
ascribes to the spleen, and which I am still disposed to
admit as a part of its office, bears an immediate relation
to the influence of temperature, and atmospheric pres-
sure, two important physical agents, upon the state of
the circulation. At the time it was written I was not
aware, although I made considerable search and enquiry,
that any similar views had been previously advanced,
nor am I yet aware that the grounds on which they rest
had been fully stated. The view which I have taken has
since been admitted by several physiologists, and a con-
tribution to a recent periodical publication, has repro-
duced the principal arguments in support of it ; but, I
believe, without any knowledge of the article which is
here reprinted. Two opinions have likewise since been
advanced ; the one by Sir A. Carlisle, that it supplies
warmth to the stomach, an idea which is by no means
new, but which, as far as I am aware, rests on no other
foundation than the antiquity, or respectability of its
supporters. The second view to which I allude, is that
of Sir Astley Cooper, who has carefully investigated the
structure of the spleen, and by different modes of pre-
paration, in which he singularly excels, has demonstrated
the capacity of its cells in various species of animals. It
is suggested by Sir Astley Cooper, that it is a part of
APPENDIX. 449
the office of the spleen to elaborate venous blood, and
thus to assist the liver in the formation of bile. My prin-
cipal reasons for doubting the accuracy of this suspicion,
consists, first, in the fact, that whilst the production of
venous blood necessarily attends the process by which
every part of the body is nourished and warmed, it is in
itself rather unfriendly than salutary, requiring the most
uninterrupted provision for its removal: secondly, in the
fact, that the supply of venous blood does not appear to
be essential to the functions of the liver, since the vena
portse has been found passing directly to the cava.]
Amongst the objects which yet remain for our investiga-
tion, after the persevering research of a vast host of acute
anatomists and physiologists who have adorned this coun-
try and the Continent of Europe up to the present day, the
uses of the spleen may, I believe, still be numbered.
In entering on the consideration of this subject, Haller
has said, " In meras hie conjecturas demergimur obscuriores
quam fere alio in viscere." When I recollect the names of
those who have already been engaged in this investigation,
I am almost induced to fear that I shall be accused of pre-
sumption in attempting to meddle with it; but, on the other
hand, I am tempted into a field, so far cleared by then-
labours.
It is, I apprehend, perfectly needless for me here to say
any thing of the structure or situation of the spleen ; but,
before attempting to explain the office which, I conceive,
this viscus is destined to perform, I may, perhaps, be al-
lowed hastily to glance at the theories which have already
been advanced. Some of them are, however, almost too
ridiculous to deserve notice. One while it was considered
the seat of melancholy, then of merriment ; while some
have held that it was connected with generation. Aristotle
G G
450 APPENDIX.
thought that it received vapours from the stomach, to con-
vert them into different fluids. Franciscus Velinus ima-
gined that, in it, the fluids of the stomach were converted
into blood ; Stukely, that it acted as a sponge, and that,
at will, blood might be pressed from it either into the arteries
or the veins, as well as that it furnished blood to the geni-
tals. Harrison thought it furnished a mucilaginous fluid ;
and Rivinus, that its secretion lubricated the viscera of
the abdomen. Some have attributed to it a muscular
power, by which it can compress its vessels (Willis) ;
others, that it supplied the stomach with warmth ; that it
balanced the liver ; or, that it rendered the blood of the
vena porta? more alkaline and fluid, in order to obviate any
danger of obstruction and scirrhous induration, which its
slow circulation, and the deterioration it had undergone in
the omentum and mesentery, might induce ; that the blood
acquired new properties in the spleen, by delay in its cells
and large veins, and by its proximity to the fetid contents
of the colon. It was the opinion of Malpighi, and, from
him, revived by many others, that it prepared the blood
for the formation of the bile ; while others have not been
wanting who denied its being of any use.
More recently, that indefatigable physiologist and anato-
mist, William Hewson, conceived that, in the cells of this
organ, the red particles of the blood were completely formed
round smaller particles, the production of the thymus and
lymphatic glands. His theory has now shared the fate of
its predecessors. His ideas respecting the red particles have
been proved erroneous ; and, though the delicate injections
of Dr. Haighton have clearly shown the cellular structure
of the spleen, yet these cells are not such as William Hew-
son had conceived them to be.
Sir E. Home, in two papers read before the Royal Society,
London, in 1807 and 1808, advanced the ingenious specu-
APPENDIX. 451
lation, that the spleen relieved the stomach of superflu-
ous fluids which passed into it by direct communication;
though, in 1811, he withdrew this opinion, which there-
fore requires no further comment. I may, perhaps, be per-
mitted to say, that the interesting experiments which he has
related in these papers are not less valuable than if they had
fully confirmed the views of their author. No arguments
which have as yet been advanced, appear to me more
strongly to support the idea, that some part of the process
of absorption devolves on the veins. They likewise tend to
strengthen an opinion which I have for some time enter-
tained, and which I hope soon to bring to the test of expe-
riment, that those fluids which are taken up by the veins
are either acids, or stand similarly situated in Professor
(Ersted's arrangement, while the absorbents receive those
of the opposite class.
The theory which I believe at present meets with the
most general support, is that of Dr. Haighton. After hav-
ing proved that the blood drawn from the splenic veins does
not sensibly differ, as Hewson had asserted, from that of
other veins ; and that the bile of an animal whose spleen
has been removed, is not necessarily changed in any re-
spect, as Malpighi has said, — Dr. Haighton advanced it as
his opinion, that the spleen was subservient to digestion in
another way, occasioning an increased secretion of the gas-
tric and pancreatic fluids, at the precise time when, they
are most required. In explaining the mode in which this
effect is to be produced, he agreed with Haller in the opi-
nion, that the stomach, when distended with food, makes
sufficient pressure on the spleen to supply its cells, and to
direct the blood commonly sent to it to the stomach itself,
and to the pancreas. The late lamented Henry Cline, j unior,
about the same time, was induced to come to a similar con-
clusion.
g g 2
452 APTENDIX.
This speculation, which has deservedly gained many
admirers, is not, as Dr. Blundel, the nephew and ingenious
successor of Dr. Haighton, very candidly acknowledges,
perfectly free from objection; noticing, at the same time,
the fact, that Nature can, on occasion, supply particular
organs with an increasing quantity of blood, without such
a contrivance, e. g. the nipple, combs of cocks, &c. ; that,
in ruminating animals, the spleen is not connected with the
digesting stomach, which ought more particularly to require
its assistance ; and he hence concluded, that though the
office which Dr. Haighton had assigned to the spleen is
probably one of the functions which it has to perform,
others may also belong to it, which remain to be discovered.
Besides these objections, which are admitted by Dr. Blun-
del, others I think may yet be urged against Dr. Haighton's
theory. It appears to me that an elastic, easily distendible
bag, like the stomach, filled with a soft pultaceous mass of
masticated food passing into chyme, and enclosed by the
yielding parietes of the abdomen, is ill adapted to expel
the blood from the innumerable spherical cells of the spleen,
or to resist the flow of blood through the splenic artery.
Nor, were it capable of doing this, can I conceive that it
would favour the healthy secretion of either the gastric or
pacreatic juices. Hsemasemesis might more naturally be
expected.
Having now endeavoured to show, that all the specula-
tions as yet advanced respecting the spleen are liable to
objections, it remains for me, as briefly as possible, to ex-
plain the opinion which I was induced to form concerning
this organ, when considering the subject rather more than
a year ago.
The structure and situation of the spleen — the different
appearances it assumes, according to the circumstances
under which death has taken place — the causes which de-
APPENDIX. 453
range it, and the effects which it produces on the system
when deranged — together with the result of experiments
made on inferior animals, conspire to induce me to believe,
that the spleen performs in the animal system, a similar
office to that which tubes and valves of safety do in various
kinds of chemical and mechanical apparatus.
The comparison may, perhaps, be thought a strange
one ; but, I believe, it will make my idea sufficiently intel-
ligible when I say, that I imagine that the office of the
spleen resembles that of the middle tube of a Woulfe's ap-
paratus. By this I wish it to be understood, that the spleen
tends to obviate any inconvenience which might arise from
a sudden disturbance of the proportion between the capa-
city of the vascular system, and the fluids which circulate
in it. These disturbances must, I conceive, be frequently
induced by various causes to which animals are continually
exposed, and which operate more powerfully than the elas-
ticity of the vessels alone can compensate for, and more
rapidly than absorption, secretion, and excretion can, in
every case, counteract.
It will now be proper that I should enumerate the rea-
sons which, if I am not mistaken, support me in this
opinion.
1 . The structure of the spleen.
The cells of this organ appear admirably calculated to
admit, with impunity, of a protracted congestion of blood
in them, which, in other parts, would necessarily be fol-
lowed by consequences of the worst nature. On the one
hand, these cells are sufficiently minute to bring the blood
so much into contact with the solid vital parts as to remove
every danger of coagulation which takes place when blood
escapes from its vessels ; and, on the other hand, those
changes are not likely to be effected in it, at least with the
454 APPENDIX.
usual rapidity which takes place when the blood enters the
ordinary minute terminations of vessels. In addition to
this, these spherules have this advantage, that they will
be less likely to yield and rupture under the sudden dis-
tension produced by the accession of a large quantity of
blood.
2. The idea is not a little supported, as I apprehend, by
the situation of the spleen. I have already said, that it
seems improbable that it can receive from the stomach that
degree of pressure which, according to the theory of Dr.
Haighton, it is necessary that it should do ; and here I
may add, that it appears highly probable that the spleen is
placed in contact with the stomach • for this very reason,
that, of all the viscera of the abdomen, the stomach is the
least likely to interfere with the variations of its dimensions,
as well as for the sake of the protection which, in this situa-
tion, it receives from the ribs.
Not less consistent with this idea of the functions of the
spleen, is its connexion with all the viscera of the abdomen,
through the medium of the vena portse, which, probably on
this account chiefly, has not been furnished with valves.
3. The great variety which is met with as to the size of
the spleen, has I believe been long observed, and has tended
to add to the perplexity in which the function of this organ
has been involved.
Should the limited observations, which it has been in my
power to make with regard to this point, be confirmed by
the experience of others, this variety will add support to
the speculation which I have advanced. In persons who
have died suffocated, I have found the spleen large and
turgid ; but, in a man who died from the bursting of a large
aneurism, which extended from the origin of the cceliac ar-
tery quite into the pelvis, the spleen was small and flaccid.
APPENDIX. 455
Should such coincidence not be found to exist in all cases
of death from similar causes, this circumstance alone will
not amount to a refutation of my opinion ; for we cannot
but suppose, that, in different individuals during life, this
function of the spleen must be more or less forcibly and ex-
tensively called into action, by which the growth of the
organ must be affected to a degree which the circumstances
occurring at death cannot, in every instance, be able to
countervail.
4. Before proceeding to relate some experiments which
have been made in relation to this subject, it will be as well
to mention a few pathological facts which may be advanced
in support of my opinion.
First, as to the causes which tend to produce disease
of this viscus. Of these, none is more remarkable, and
at the same time of more frequent occurrence, than inter-
mittent fever.
In the cold stage of an intermittent, when the vessels of
the surface are often suddenly diminished in capacity, and
when, consequently, a large quantity of blood must be as
suddenly thrown upon internal parts, an organ acting the
part which I have here attributed to the spleen, must be
called into unusually active service, at a time when the
febrile state checks those secretions by which it is to be itself
relieved, and the balance between the circulating fluid and
its vessels is to be preserved. What else could we expect
of an organ frequently called into excessive service of this
kind, but first increased growth, and afterwards, should
the cause continue to operate, derangement of structure ?
Those who die of ague are, it is well known, almost in-
variably cut off in the cold stage, and the spleen is either
found prodigiously gorged with blood, or actually ruptured.
More frequently, however, the complaint being less urgent,
456 APPENDIX.
proceeds to the derangement of the spleen, and effects are
produced which I shall presently have to consider.
Another complaint which leads to the derangement of
the spleen, is amenorrhoea ; and the mode in which it acts,
admits, I apprehend, of as easy an explanation as the pre-
ceding case, provided the functions which I have supposed
be attributed to the spleen.
Secondly, A very few words will suffice with regard to
the effects produced by the structure of the spleen becom-
ing so far deranged as to disable it from fulfilling its func-
tion. Either haemorrhage or serous effusion is, I believe,
the almost invariable consequence induced, as I conceive,
by the small vessels being unable to sustain the shock oc-
casioned by a sudden disturbance of the balance between
the capacity of the vascular system and the circulating
fluid ; which shock, in the healthy state of the spleen, is
in a great degree broken by it, assisted, no doubt, by the
elasticity of those vessels which have not been exposed to
the constricting cause.
5. I shall now relate a few experiments on inferior ani-
mals, and then conclude.
An experiment related by the ingenious and indefatigable
B. C. Brodie, in his Lectures delivered last summer at the
London College of Surgeons, appears to me to strengthen
my opinions, though the object for which it was instituted
was not connected with an inquiry into the office of the
spleen. The vena portas of a dog was obstructed by a liga-
ture, just as it enters the liver. After some hours uneasi-
ness the animal died ; and, on examination, the abdominal
viscera, as we must conceive, would necessarily have been
the case, were found charged with venous blood. This,
however, was most remarkably the case with the spleen,
which was gorged with blood, and prodigiously distended.
APPENDIX. 457
Here the spleen seems to have performed its part to the
utmost ; but the relief which it in its turn requires, being
cut off by the ligature on the vena portse, no exertion of its
function, however considerable, could preserve life.
Though it will be quite needless here to quote all the in-
teresting experiments of Sir E. Home, to which I have before
alluded, since they have now been long before the public ;
yet I cannot forbear availing myself of the support which I
may derive from such respectable authority, by noticing a
few of the circumstances which occurred in the performance
of them. Infusion of rhubarb was repeatedly given to dif-
ferent animals, and invariably the spleen was found turgid,
and its blood impregnated with the rhubarb ; and this, not-
withstanding that the thoracic duct and right trunk were
secured, and that the chyle exhibited no trace of the drug.
Nor did the part of the canal, from which the absorption
took place, appear to cause any difference, as the same re-
sults are obtained, whether the infusion was lodged in the
stomach, as in the experiments made on the dogs and rab-
bits, or in the larger intestines, as in the ass. I would
here inquire, Does not this look like venous absorption ? —
for what other system of vessels is there, which, in this case,
could communicate at once with the stomach, intestines,
and spleen?
The experiments of Sir E. Home further prove, that this
passage of the absorbed fluid into the spleen, is neither at
all times necessary, nor invariably taking place; for the
spleen, he has since shown, may be removed without pre-
venting the rhubarb from finding its way into the system.
But I would more particularly solicit attention to the fol-
lowing fact. In all the preceding cases, fluids had been
injectsd, andthe spleen was full and distended. When,
however, the rhubarb was given in substance, and the ani-
458 APPENDIX.
mal deprived of water, which was done for four days, in the
case of one ass which Sir E. Home subjected to his experi-
ments, the spleen was found contracted to half the size of
what it was seen in the former experiment, and its sub-
stance was also as much condensed as that of the liver ;
nor did the blood from it, in such cases, exhibit any very
marked indication of the presence of rhubarb, at least not
more than in the other parts of the body, though its pre-
sence in the urine proved that it had been taken into the
system. Sir E. Home has remarked, " that the spleen is
met with in two very different states, one of which may
be termed the distended, and the other the contracted ;
and that, in the one, the size is double what it is in the
other."
In the distended state, there is a distinct appearance of
cells, containing a limpid fluid, distinguishable by the
naked eye. In the contracted state, these only become
distinct when seen through a magnifying glass ; the dis-
tended state takes place when the stomach has received
unusual quantities of liquids before the animal's death ; and
the contracted state, when the animal has been kept se-
veral days without drink before the spleen is examined.
In a subsequent paper, he states his belief that this limpid
fluid is the peculiar secretion of the spleen, which is con-
veyed to the thoracic duct by the lymphatics of the organ,
which are, as he has said, larger in this than in any other
organ. " The purposes," he adds, " that are served by
such a secretion from the spleen into the thoracic duct,
cannot be at present ascertained." If I might be allowed
to offer an explanation of the preceding facts, it would be
the following.
Consistently with the idea, that the spleen is to main-
tain the balance between the circulating fluid and the ves-
APPENDIX. 459
sels destined to contain it, we cannot be surprised to find
it in its turgid state, at a time when absorption is making
large contributions to the former ; and more especially if
we admit, as I cannot help doing, that the veins take a
share in the process of absorption. The contracted state is
not less accordant with that state of the system which must
be induced by secretion being continued, while the accus-
tomed supplies are withheld. As to the fluid conveyed from
the spleen to the thoracic duct, and which Sir E. Home
has considered as the secretion of this organ, I must beg
leave to hold a different opinion, and to regard it as merely
the effect of ordinary lymphatic absorption actively going-
forward to relieve the spleen of the load which the other
viscera are throwing upon it. The whitish corpuscules, I
imagine, are intimately connected with the lymphatic sys-
tem. I have found them particularly conspicuous in a cat,
whose lymphatic glands, throughout the body, were remark-
ably large.*
If my speculations should prove correct as to the nature
of the matter taken up by the absorbents and veins, it may
account for the absence of any trace of rhubarb in the fluid
contained in the absorbents, and also for the strong signs
of it, which Sir E. Home so repeatedly observed in the
splenic vein. William Hewson had also observed the fluid
contained in the lymphatics of the spleen. The red colour
which he observed in it must, I imagine, be attributed to
some extravasation, the consequence of congestion, occa-
sioned by the ligature which he had applied.
* Some experiments have been made on this subject by my friend Bracy
Clark, a very ingenious and scientific Veterinary Surgeon, who has thrown much
light on the feet of animals with undivided hoofs, and has investigated, with great
success, the habits of oestri, as well those peculiar to other animals as to the
horse. I have not yet been able to procure the detail of his experiments ; but,
from the sketch which I have received, I believe they will rather confirm me,
than not. He has not himself advanced any opinion grounded upon them.
460 APPENDIX.
In the 8th month (August) last, after dividing the spinal
marrow of" a cat, I opened her abdomen, and immediately
immersed her in cold water, taking care not to admit the
water into contact with the viscera of the abdomen. The
spleen became sensibly turgid. This seems to prove, as far
as the result of one experiment can do so, that the spleen
is, in the mode which I have hinted at, subservient, not
merely to the vessels of the abdomen, but to those of the
system generally. The derangement produced in this vis-
cus, by intermittent fever, tends to the same conclusion.
I have not been able to learn whether any peculiar symp-
toms were discoverable in the two instances which are re-
corded, of the spleen having been extirpated in the human
subject ; but some of those which have been observed in
dogs, from whom this organ has been removed, and which
Haller has recorded, on the authority of Jolyffe, Boyle,
Malpighi, Hunter, and some others, seem to indicate an
increased stress upon the arterial extremities ; as, e.g. an
increase in the flow of urine — a greater degree of salacity —
and the accession of plethora. In some the functions of the
liver were disturbed, and this organ itself rendered turgid.
I have now given a sketch of the principal reasons which
have led me to the opinion which I have here advanced, not by
any means as a point which I as yet regard as demonstrated,
but rather to be considered as a suggestion ; nor shall I be
surprised if some one, better acquainted with the subject
than myself, should say with Haller, " Nondum tamen
inde audeas aliquid fiimioris theorise superstruere;" yet I
am induced to trust, that there is enough of plausibility
to secure me from censure, in having ventured to bring it
forward .
It will, I have no doubt, be thought by most, that I
should myself have made more experiments with regard to
this question ; to whom 1 can only state, in defence, that,
APPENDIX. 461
besides having little opportunity for doing so, I conceived
that, by availing myself of the experiments of others, of
men of the highest celebrity, no imputation could arise of
facts having been warped to suit theory, which, by the
theorist, may sometimes be innocently done ; and further,
the performance, of these experiments would be necessarily
attended with a degree of cruelty, which would render them
alike painful to myself to undertake, and to others to hear
detailed.
Thomas Hodgkin.
Edinburgh, 4th month (April) 1821.
NOTES.
PART I.
CHAPTER I.
Page 11. — In confirmation of the opinion advanced by Dr. Edwards, that
venous blood, though greatly inferior to arterial, still contributes to produce the
action of the nervous and muscular systems, may be adduced the extraordinary
facts with which the epidemic cholera has familiarized us. We have seen indi-
viduals, whose dark and blue colour has attested the general circulation of venous
blood, exercising, though with a certain degree of habitude, the intellectual and
locomotive faculties.
Page 13. — Although in Dr. Edwards' experiments on the duration of the life of
frogs inclosed in plaster, the animals do not appear in any instance to have sur-
vived more than six weeks ; we are not on this account bound to discredit the state-
ment of Herissant, who kept them alive eighteen months, in boxes inclosed in
plaster. My friend — Hodgson of Birmingham, has informed me, they have
been kept alive for three years inclosed in globular masses of plaster, but that to
effect this, it will be necessary to keep them in a cellar at a low temperature. I
believe it is his intention to publish these, and some other interesting facts pointed
out by a deceased friend of his.
Page 37. — The fact, that fishes cannot live in water deprived of air, and yet
speedily die when removed from the water and exposed to the direct and unmixed
influence of the atmosphere, is probably in some respects analagous to what oc-
curs in the mammalia, who, though they cannot survive many minutes, when
removed from the vivifying influence of the oxygen, nevertheless require that it
464
NOTES.
be diluted with a large proportion of nitrogen, or hydrogen, and are soon cut oft'
when restricted to an atmosphere of pure oxygen. I shall have occasion to ad-
vert to the experiments of Broughton on this subject in a subsequent note.
The following is a note by Dr. Marshall Hall.
* The results of the experiments detailed in this interesting chapter, do not appear
to be all phenomena of the same kind.
It is plain that death is the result of asphyxia within certain limits of tempera-
ture. But as we approach that of 42° cent. (107° 6' Fahr.) the animal is doubt-
less destroyed, not by asphyxia, but by the positive action of this elevated tem-
perature upon the nervous and muscular systems ; the nerves are deprived of
their peculiar properties and the muscles become perfectly rigid.
The facts, however, together with those of chap. 2. sect. 1. p. 18, and that
quoted from Legallois, p. 148, demonstrate, that exposure to a low temperature,
both previous and immediate, enables the animal tribes to bear the privation of
air better than exposure to a higher one.
What is the rationale of this fact? Mr. Edwards does not offer a conjecture
upon the point. It is probable, that it depends upon augmented irritability.
The effect of exposure to cold, when the temperature of the animal falls, appears
to be, in a general point of view and within certain limits, diminished respiration
and augmented irritability.
The experiments detailed, pp. 19 and the following, appear incomplete. It
was found, that the temperature of 42° cent. (107° 6' Fahr.) was alike immedi-
ately fatal to the bactrachiae in summer and in winter ; but as the experiments
were first performed in the months of July and September, it was a question not
only whether the temperature of 42° cent. (107° 6' Fahr.) would be equally
promptly fatal in November, but whether a lower temperature would not have
been so.
It is probable, that all temperatures which reduce that of an animal, without
destroying life, raise its irritability and lower its respiration, and render it, at
once, less capable of bearing any increased stimulus, as that of heat, and more
capable of bearing diminished stimulus, as the privation of air, or of food. This
will probably be found a general law of the animal economy, equally applicable to
the warm-blooded and cold-blooded animals. It is illustrated and confirmed by
the fact quoted from Legallois, p. 148 ; and by the histories of persons or animals
buried in the snow.*
PART II.
CHAPTER I.
Page 55. — I visited the Magdalen grotto, near Adelsbevg, in 1824, and ob-
tained some of the protei from the subterranean pools which exist in it. Only
NOTES. 465
a part of the floor of the cavern was then occupied with water, and these animals
might have enjoyed atmospheric respiration had they inclined to do so, to at least
an equal degree with those which Dr. Edwards kept in an earthen vessel exposed
to the air. They were, however, deprived of the benefit of light.
CHAPTER II.
Page 56. — I have been furnished with the following authorities for fishes being
able to live in water at very high temperature, by my excellent and accomplished
friend A. R. Dusgate of Paris, from which it would appear, that in a state of
nature, fish not only live, but thrive in a temperature beyond the limit which
they were able to endure in Dr. Edwards' experiments : may not this difference
be in part referred to the influence of habit 1 Saussure, speaking of the hot
springs of Aise in Savoy, says, " I have frequently examined the temperature of
these waters at different seasons, and have always found it very nearly alike, viz.
from 35 in that of Souffre, and from 36 J to 36^ in that of St. Paul. Notwith-
standing the heat of these waters, living animals are found in the basins which
receive them. I saw in them eels, rotifera and infusoria, in 1790. I discovered
in them two new species of tremelles possessing spontaneous motion, of which
a description may be seen in the ' Journal de Physique' for 1790, p. 401." See
Saussure, Voyage dans les Alps, vol. vii. pp. 18 and 1168. Neufchatel edition
in 8vo.
Sonnerat states, that in the island of Lugon, one of the Manillas, there is a
hot spring, of which the temperature was so high as to raise Reaumur's ther-
mometer to the degree of 60, equal to 86*25 cent, or 187-25 of Fahr. Accord-
ing to his account, one could not put one's hand in it, yet he distinctly saw
fish which did not appear to be at all incommoded by the heat ; and small plants,
the agnus castus, flourishing in it. — Journal de Physique de Rosier, April 1774,
p. 256. See also Rees's Cyclopaedia and Pinkerton's Geography.
The sparus Desfontaines of Lacepede — the chromis of Cuvier, was found by
Desfontaines in the hot waters of Cafsa in Barbary, in which Reaumur's ther-
mometer rose to 30 degrees. — See the article ' Sparus' by Bosc, Dictionaire d'His-
toire Naturelle, Deterville's edition, vol. xxxi. p. 550. My friend likewise received
the same statement from the Professor's own mouth.
The following extract is from Bruce. "At Feriana, the ancient Thala, are baths
of warm water without the town : — in these there were a number of fish, about
four inches in length, not unlike gudgeons. Upon trying the heat by the ther-
mometer, I remember to have been much surprised, that they could have existed,
or even not been boiled, by continuing so long in the heat of this medium.
In opposition to the account of the hot springs at Manilla, given by Sonnerat,
must be placed that of Dr. Abel, who accompanied Lord Amherst in his embassy
to China. In his narrative of the journey, he notices visiting those springs, and
remarks, that " Sonnerat has stated, and his statement has been copied by other
authors, that a species of fish lives in these springs. It is scarcely necessary to
H H
466 NOTES.
observe, that I was unable to verify this observation. All the animals which I
saw there, and I saw two, a small snake and a frog, were not only dead, b\it
boiled ;" but he adds, " a plant vegetates in them, and in this respect my ex-
perience partially accoids with his. 1 found a small plant, apparently a species
of arenaria, vegetating in a soil that raised the thermometer, plunged amongst
its roots, to 110 degrees on the side of the spring, which was 120 degrees." —
Fourth edit. London, 1818, pp. 246-249. (It will scarcely escape the attention
of the reader, that Dr. Abel's account does not positively disprove that of Sonne-
rat. Though he appears only to have seen two dead animals, which probably
came there accidentally, it is still not impossible, that other species, under the
influence of habit, may support the temperature of some parts of the fountain.)
Shaw, after enumerating the thermal waters of Barbary, adds, " The ain el
houte (fish fountain) and the springs of Cafsa and Tozer, nourish a number of
small fishes of the mullet and perch kind." — Shaw's Travels in Barbary, folio
edition, Oxford, 1738, p. 231.
The late lamented Baron Cuvier, whilst engaged in publishing his great work
on fishes, was reminded of these observations by my friend, and in consequence
wrote to M. Marcescheau, the French vice-consul at Tunis, who, not only con-
firmed the fact in his reply, but sent him two long-tailed fresh-water turtles,
from a basin of water at Utica, of which the water is at the temperature of 36
degrees of Reaumur, or 113 of Fahr. The vice-consul also sent some fishes
from the hot waters of Cafsa and Tozer, which proved to be chromis or spari
Desfontaines of Lacepede. These waters were said to be as warm as 62 degrees
of Reaumur.
Breislak in his Institutions Geologiques, has an article on this subject.
Amongst other facts, to those above noticed, he adds, that Dunbar and Hunter,
in their journey made in 1804, along the Washila or Ouachita, a river of
Louisiana, observed above Fort Meiro, on the frontiers of the United States,
springs of the temperature of 40 degrees to 50 degrees of Reaumur, or 122 to 145
Fahr., in which were not only growing conferva, and herbaceous plants, but also
shrubs and trees. They likewise found in them bivalve molnsca.
Lamark, in his Histoire des Animaux sans Vertebres, states, that the paladina
muriatica is found in Italy and in Fiance, especially in the south, inhabiting in
fresh water, and has been met with in water of the temperature of 34 degrees
Reaumur, 109 Fahr.
To these instances presented by nature, of animal and vegetable life, maintained
at high temperatures, my friend Dusgate adds the following extract from an ar-
ticle by Bosc, in the Dictionnaired' Histoire Naturelle, torn. xxxi. p. 551. "The
facts mentioned by Sonnerat, and other travellers, induced Broussonnet to make
some experiments on the degree of heat which our river fish are capable of endur-
ing. I have no detail of the result of his observations, although I took a part in
them ; but many species lived for several days in water, which was so hot that I
could not bear my hand in it for a single minute."
NOTES. 467
I have not brought forward these curious facts, with the intention of disputing
the general accuracy of the limits of high temperature assigned by Dr. Edwards,
as consistent with the life of fishes. As exceptions to it, they may be apparent
rather than real, since it is by no means impossible, that the heat of that part of
the water in which the fishes were seen, might not be exactly the same as that
in which the thermometer was placed. If they cannot in this manner be ex-
plained away, they afford a very legitimate object for further enquiry. The fol-
lowing fact is quite compatible with the limit given by Dr. Edwards, but it is
interesting as shewing, that a very considerable degree of warmth is not only sup-
ported, but very congenial to some species of fish. It is well known, that in
manufacturing districts, where there is an inadequate supply of cold water for the
condensation of the steam employed in the engines, recourse is had to what are
called engine dams or ponds, into which the water from the steam-engine is
thrown for the purpose of being cooled ; in these dams, the average temperature
of which is about 80 degrees, it is common to keep gold-fish, the ciprinus aureus;
and it is a notorious fact, that they multiply in these situations much more rapidly
than in ponds of lower temperature exposed to the variations of the climate. Three
pair of this species were put into one of these dams, where they increased so ra-
pidly, that at the end of three years, their progeny, which were accidentally poi-
soned by verdigris mixed with the refuse tallow from the engine, were taken out
by wheelbarrows-full. Gold-fish are by no means useless inhabitants of these
dams — they consume the refuse grease which would otherwise impede the cool-
ing of the water by accumulating on its surface. It is not improbable, that this
unusual supply of aliment may co-operate with increase of temperature in pro-
moting the fecundity of the fishes. My friend, Charles May, of Ampthill, to
whom I am indebted for the fact just related, has communicated to me another
fact in proof of the high temperature which vegetable life is sometimes capable of
enduring. —John Daulby, brother to the curator at the Botanic Garden, at Liver-
pool, brought from Iceland, a short time since, a species of Chara, which he
found flowering and producing seed in one of the hot springs of that island, in
which he states, that he boiled an egg in four minutes.
PART III,
CHAPTER II.
The remarks of Dr. Edwards, respecting the hybernating mammalia, induced
me to query, whether there might not be some species amongst the class of birds
possessed of a similar constitution, as respects the influence of temperature. The
migrating birds, which quit this country on the approach of cold weather, seemed
the most likely to be of this description. The season was far advanced, and
swallows had for the most part left the country, when this idea occurred to me.
Through the kindness of a friend I obtained two individuals, which enabled me
to perform the following experiment : —
H H 2
468 NOTES.
With a small and very delicate thermometer, I ascertained the temperature of
the swallows to be 106° Fahr., that of the laboratory in which the experiment
was performed, being nearly 70°. One of the birds was then placed in a deep
glass vessel, immersed in a mixture of ice and salt. Although the bird remained
quiet, its respiration soon became greatly accelerated, and its temperature, in
somewhat less than an hour, was reduced about 20 degrees. It is not easy sa-
tisfactorily to ascertain the temperature of so small animal as a swallow. In this
instance the temperature was examined with a small thermometer, carefully
placed under the wing, which was kept applied to the side. Although the extra-
ordinary powers of flight possessed by swallows, and other migrating birds, gene-
rally enables them to avoid that degree of cold, which their constitutions are not
calculated to resist ; it is extremely probable, that if they survived detention in
this country, after the setting in of cold weather, they would fall into a state of
torpor. The brumal retreat of swallows, has long been a subject of speculation
and controversy, and numerous anecdotes of their having been found in a state of
torpor, are related by those who maintain the opinion that they do not quit the
country, but retire to various places of concealment during the winter. Some of
these statements may rest on questionable authority, but I am convinced that
others are too well attested to admit of rejection. As an example of this kind, 1
might cite the following incident which occurred to my friend, James Browell of
Guy's Hospital. I will relate it in his own words : —
" I will endeavour to give you as clear an account as I can of the circumstances
relating to the habits of the swallow, which came under my notice at a period of life
not very prone to philosophise on things seen. The impression on my mind is very
vivid, though the distance of time is half a century.
" Residing with my parents in Hampshire, so near the sea that the high tides
reached the walls of the house, after morning school, I was occupied in the boyish
play of throwing up a ball in the back yard, which fell into a butt placed for re-
ceiving the rain water from the roof of the house. It was in the winter, though
not a wet time, as the cask was only half full. On my getting up to the edge of
the water cask, and leaning over into it, sweeping my hand round in search of
the ball, my hand touched the bung cloth, a little under the water, and I felt
something which induced me to move it, and found it, on examination, to be a
bird in a torpid state, perfectly wet and to appearance inanimate. Whether I
had heard any thing said on the subject, or what is not very probable at about
nine years of age, had read about it, I cannot recollect ; but I remember well,
leaving the ball and taking my prize to the kitchen fire, which after drying and
warming, I had succeeded in restoring to perfect animation my bird ; when my
mother found me there, and it was time for me to go to school ; my entreaties to
be allowed to complete my restoration were not attended to, and I received orders
to let the bird fly when it could, and it was put opposite an open window, facing
the sun, and on my return from school, no trace of my protegee could be found."
NOTES. 469
Dr. Marshall Hall has obliged me by furnishing me with his
remarks respecting the subjects of this PART. They are in-
cluded between asterisks.
CHAPTER I. III. IV. V. and VI.
* This interesting series of experiments, admits of a ready association and expla-
nation, by a reference to the law, that the quantity of respiration is inversely as
the degree of irritability, and the facts, that the activity of the animal is directly as
the former, and that its tenacity of life under the privation of air, food, and other
stimuli, is directly as the latter. The very young animal has a lower respiration,
and a higher irritability than the adult. It has less power of evolving heat, and
greater power of bearing the privation of air.
The adult animal has a higher respiration, and a lower irritability. It has
greater activity, and less tenacity of life, under the privation of air and food.
The animal which maintains a steady given temperature, has a higher respi-
ration, and a lower irritability, in winter than in summer. Animals, which do
not maintain their temperature, have a lower respiration, and a higher irritability,
in winter and summer. When the cold induces the state of torpor, these phae-
nomena are observed in a still more marked degree, and the animal bears asphyxia,
and the privation of food, with comparative impunity. The fact quoted from
Legallois, p. 148, and the case of animals buried under the snow, already no-
ticed, are sufficient proofs of this fact.
CHAPTER II.
It appears to me that the case of the young animal, is incorrectly compared with
that of the hibernating animal. The former lose their heat whenever they are
exposed singly to the influence of the atmosphere, even in moderate temperatures.
The hibernating animal, on the contrary, maintains its temperature unimpaired,
even when the thermometer is pretty low.
Besides this remarkable difference, there is another which has not, I believe,
been pointed out. It is that sleep invariably intervenes, in the hibernating ani-
mal, between its power of maintaining its temperature, and the order of phe-
nomena, of which the loss of temperature constitutes one, and one so remark-
able.
I cannot, therefore, agree with the inferences of this Chapter, and of p. 155.
Under ordinary circumstances, the hibernating animal maintains its own tem-
perature. It has, therefore, the full power of evolving heat. The loss of this
power is an induced condition, not hitherto noticed, and is observed in the or-
dinary sleep of these, and, indeed, of all animals, only in a less degree, than in
true lethargy, or hibernation.
It is further obvious, that a due distinction is not made between hibernation,
and the torpor which may be induced by cold in any animal, and especially the
470 NOTES.
young. Legallois commits this oversight. (See p. 148, and the (EuvresdeLagal-
lois, torn. i. 282.) The first condition is preservative, the second destructive of
life*
To the objections of Dr. Marshall Hall, already given in his own words, may
be added those of Dr. Holland, respecting the temperature of young animals.
The Doctors agree in this respect — that they regard the inferior power of resisting
the influence of exposure to cold, which hibernating mammalia, and very young
individuals of the class of birds, and mammalia, generally possess, as not indi-
cative of a constant inferiority in the power of producing warmth ; since under
different circumstances, and a higher temperature, their animal heat exceeds
that of the ordinary temperature of the atmosphere, as much, or more than is
known to be the case, with those adult mammalia which possess the strongest
power of resisting cold. Dr. Holland found the mean temperature of forty infants,
aged from one day to eighteen months, to exceed that of the same number of
adults, by 1 f°. Twelve children possessed a temperature of 100° to 103j°,
whilst in no instance did the temperature of adults exceed, and in one instance
only did it reach 100°. The solitary observation made by myself on swallows^
shows the high temperature which they are capable of raising themselves, in con-
junction with a very feeble power of maintaining it. I do not consider that the
objections of either of the physiologists, whom I have mentioned, undervalue the
credit or importance of Dr. Edwards's observations on the relations which young
and hibernating animals bear to external temperature. Without disturbing the
practical inferences to be drawn from what has been stated by Dr. Edwards, they
are of great value in themselves, not only by correcting one of his deductions,
but as leading us some steps in advance into the inquiry concerning the physical
and vital conditions, concerned in regulating the phenomena in question. Dr.
Hall considers that a different degree of irritability, possessed by young animals,
by hibernating mammalia, and in some degree even by other adult mammalia,
which have been exposed to the continued heat of the summer season, is the
constant associate of their inferior power of resisting external cold, t
I confess that I am much disposed to adopt this view, which, so far from ar-
resting the progress of inquiry by interposing the mysterious agency of the nervous
system as an insuperable obstacle, ought rather to assist our investigation con-
cerning the functions of that system. Dr. Holland, in his experimental inquiries
into the laws of life, takes a different view of the subject. He, as well as Dr.
Hall, has ably pointed out the fallacy of some of the conclusions of Dr. Wilson
Phillip, and others, with reference to the agency of the nervous system ; but 1
cannot help suspecting, that he has carried his objections somewhat too far, and
thereby been led to regard the functions he has examined, as more independent of
t See two papers in the Philosophical Transactions on Hybernation and on
the Inverse Ratio which subsists between Irritability and Respiration, by Dr.
Marshall Hall, 1832.
NOTES. 471
the nervous system than is really the case. Be this as it may, the view which he
has taken has had one important influence on his investigations. It has led him to
pay a very careful and undivided attention to the varied conditions of the circu-
lation and respiration, functions, which certainly stand in the closest relation to
the production of animal heat.
Dr. Holland lays it down as an axiom, on which he strongly insists, and which
he makes the basis of several other principles, which it is his object to establish,
that animal heat is in the inverse ratio to the quantity of blood exposed to oxygen
in the lungs ; and he opposes the opinion of Dr. Edwards, that it is in the direct
ratio to the quantity of oxygen consumed. Dr. Holland insists on the opposite effect
produced by inspiration and expiration. The latter tends to expel blood from the
thorax, and to oppose its return thither, consequently, when the force of the ex-
pirations predominates over that of the inspirations, the quantity of blood in the
lungs is diminished, and the production of animal heat is increased with the di-
minished proportion which the blood bears to the inspired air. He illustrates this
by various kinds of exercise, by the effects of the exhilarating passions, and of some
diseases. He is obliged, however, to admit the acceleration of the circulation, by
which the mass of blood is brought more rapidly and frequently under the in-
fluence of inspiration, to be one of the causes of the increase of temperature.
A predominance of inspirations, he represents as producing precisely the op-
posite effect. It increases the quantity of blood in the lungs, and, consequently,
its proportion to the inspired air. Hence it is followed by a manifest reduction
of temperature. The depressing passions, bodily inactivity, and various diseases
productive of congestion of blood in the lungs, but more especially asthma, are
adduced as illustrations of this point of the Doctor's views. He attributes the
diminution of the production of heat, occasioned by a sudden, or temporary ex-
posure to cold, to be owing to the altered condition of the circulation — the sur-
face of the body becomes pale, because the capillaries cease to be filled with
blood — the internal organs are loaded at their expence, and the blood in the
lungs bears a larger proportion to the inspired air. Though he differs from Dr.
Edwards in regarding their young animals as capable, under favourable circum-
stances, of raising their temperature to as high, or even a higher degree than that
of adults, he of course admits their inferior power of maintaining it, in spite of ex-
posure to cold, and attributes this to the difference in the character of the circulation
at different periods of life ; that of the young animal, is what he calls external, the
blood sent to the surface bearing a larger proportion to that with which the internal
parts are supplied, than is the case with the adult, whose circulation possesses,
what the Doctor calls the internal character ; this change he attributes to the
successive development of particular organs. In the young animal, at birth, the
internal organs present their minimum of activity, digestion calls an encreased
quantity of blood to the chylo-poietic viscera — the lungs continue to receive an
increasing quantity of blood as the thoracic viscera are developed under the in-
fluence of respiration and exercise. The exercise of the functions of the brain
472 NOTES.
makes a demand in that direction, and the last additional demand is made as
the period of puberty takes place by the development of the sexual organs. The
habits and passions of the young animal concur with its organization to give the
external character to its circulation, whilst those of the adult concur with the or-
ganic changes which it has undergone, in producing the preponderance of the
internal circulation. It is to these differences, which I have briefly sketched,
that Dr. Holland refers the inferior power which the young, compared with the
adult animal, possesses, of resisting cold. When cold has constringed the vessels
of the surface, a larger quantity of blood is thrown upon the internal organs, which
receive it, with a less proportionate capacity of vessels, than in the adult. The
proportion which the blood in the lungs bears to the inspired air is increased, and
the production of heat, according to the Doctor's hypothesis, is diminished as a
consequence. Adult animals in summer have a circulation of a more external
and juvenile character than in winter; hence their power of producing heat is
liable to a similar reduction by the application of cold. Dr. Holland brings for-
ward several interesting facts, and employs considerable ingenuity of reasoning to
support of his views, and to exhibit the importance of their application ; they do
not, however, appear to contain the whole truth. Why does the vigorous adult
maintain the ruddy colour of his well-injected skin in a temperature, in which the
infant would be pale and benumbed with cold 1 Dr. Holland himself remarks,
that the greater vigour of the adult enables him to resist cold better than the in-
fant. The reader is left to form his own opinion of what this vigour consists, and
I confess, that I think this is to be found in the different condition of the nervous
system, which Dr. Holland appears not to take into account in his investigation
of the calorific process.
I must return to his objection to Dr. Edwards's view regarding the produc-
tion of heat, when we shall have to consider the changes of the air effected by
respiration.
[The following experiments, which the kindness of Sir Astley
Cooper has allowed me to extract from amongst several re-
corded in one of his Memorandum Books, dated 1790, anti-
cipate and corroborate some of the observations of Dr. Ed-
wards. — They have not to my knowledge been hitherto pub-
lished.]
Experiment I. — A young puppy was immersed in warm water, at about
120° Fahr. for one minute and a half. It struggled violently, and during the
latter part of this time threw out the air from its lungs. It then remained still
for another minute and a half, when its struggles were renewed, at which time
it voided its excrement. These efforts were soon over. After remaining still for
three minutes, it was put into another vessel containing water of the same tem-
perature. In this it gasped twice or thrice. In ten minutes after its first immer-
sion I opened it — a slight undulation was observable at the lower part of the
NOTES. 473
right auricle of the heart, and there was some motion in the intestinal canal.
The action of both ceased in about a minute, and could not be reproduced by the
irritation of touching and piercing it. Thus, then, the action of the heart was
destroyed eleven minutes after its first immersion.
Expeeiment II. — A puppy, of the same age as the last, was immersed in
water, at about 56° Fahr. For one minute and a half its voluntary motions con-
tinued violent — it expired the air from the lungs, and then was quiet. At the
end of another minute and a half its struggles were renewed. Its excretions
passed off. For two or three minutes after it continued to gasp. It was then
thrown into another vessel containing water of the same heat. It gasped at the
end of every minute, and ten minutes after its first immersion it was opened.
The heart acted vigorously, and there was strong peristaltic motion in the intes-
tines. The action of the heart continued strong for nineteen minutes after it was
opened, when it began to undulate — it undulated for four minutes, when all ac-
tion ceased. At the end of twenty- nine minutes, then, the heart of this animal
acted as strongly as that of the first, which died in ten minutes.
Expeeiment III. — A puppy was immersed in water heated to 90° of Fahr.
for a minute and a half. It continued to struggle violently another minute and a
half — it remained motionless — when it began to struggle again, and for half a
minute continued to do so. At the end of ten minutes it was opened. The lower
part of the right auricle undulated, and continued to do so seventeen minutes
after it was opened, when no motion could be produced by the stimulus of vinegar,
or by the irritation of pricking it.
Expeeiment IV. — A puppy of the same age was immersed in cold water.
The first minute and a half it struggled. It remained quiet for one minute and a
half, then struggled again. It continued to struggle at the fourth and fifth mi-
nute for one quarter of a minute. At the tenth minute it was opened. The heart
contracted strongly in every part, and the intestines moved. Eighteen minutes
after opening the animal, the heart contracted more strongly than that of the third
experiment did at first, and it continued to undulate six minutes after ; so that it
acted twenty-four minutes from the opening of the chest.
Expeeiment V. — A kitten was put into cold water, and after about two mi-
nutes ceased to struggle. For some minutes after it had convulsive motions.
Twelve minutes after it was immersed, its abdomen and thorax were opened.
The heart was contracting, and the intestines moving. The heart continued to
do so for half-an-hour.
Expeeiment VI. — A. kitten was immersed in water heated to 100° Fahr. Its
efforts seemed rather more violent than those of the other in the fifth experiment.
Its convulsions were sooner discontinued. Twelve minutes after its immersion it
was opened — no action could be observed, either in the heart or intestines, nor
could it be produced by stimuli or irritation.
Expeeiment VII. — A snake was opened after having been immersed in rec-
tified spirits of wine in order to destroy it. It coiled itself up, became rigid, and
474 NOTES.
was supposed to be dead. In opening it, it shewed some voluntary power, and
its heart was found beating strongly. It was put into a vessel of cold water, and
the action of the heart became languid and slow. It was then thrown into water
heated to about 80° Fahr. — the action of the heart became quick and vigorous,
and it began to move freely in the vessel, recovering its voluntary motions, al-
though its body was opened. It was then returned into cold water — its volun-
tary power lessened, and its heart acted less frequently and vigorously.
Experiment VIII. — The atmosphere being at 61 £° Fahr., a thermometer was
introduced into the belly of a viper, and it stood at 76°.
Experiment IX. — Water was heated to 99|° Fahr. A viper was plunged in
and kept there ten minutes. The thermometer stood in its belly at 92°, but soon
fell.
Experiment X. — A viper was exposed to air heated to 102° Fahr., and kept
there fifteen minutes. The thermometer stood in its belly at 96°.
Experiment XI. — A viper was exposed to air at 34° Fahr. It became torpid
in a considerable degree — it was retained in this stupefaction fifteen minutes.
The thermometer stood in its belly at 42°. Nitre and muriate of ammonia, in
equal parts, were used to produce this degree of cold. From these last experi-
ments it appears, that the viper is subject to great changes of its temperature by
the surrounding atmosphere, which corroborates the idea of Dr. Crawford, — " for
these reptiles have their blood but very partially heated ; hence their power of re-
sisting high and low degrees of heat must be weak."
Experiment XII. — I put a kitten six weeks old into water, which I kept at
323° Fahr. by putting in it small pieces of ice. Its mouth was above water. It
died at the end of sixteen minutes. During almost the whole of the first five
minutes it laid quiet in the water, but its nose, lips, and gums, which were pre-
viously pallid, soon after immersion, became of a beautiful vermillion colour.
It struggled violently during the second five minutes. Between the tenth and
sixteenth minutes it laid quietly. It breathed first quickly, then laboriously, and
lastly at long intervals, when it died. Upon introducing a thermometer, imme-
diately after the last breath, into the chest, it stood at 52°. The heart did not
act. The blood was of a florid red in the left side of the heart. The peristaltic
motion of the bowels still continued. When touched, the heart acted ; but was
quite motionles, unless thus stimulated. An hour and thirty-five minutes after
its apparent death, I poured warm water at 90° or 100° into the chest. The heart
began to act, and continued to do so for more than two hours ; therefore, four
hours after the chest had been laid open. The blood in the mesentery was very
florid.
Another experiment, almost in every respect similar, is related as tried upon
a puppy a month old. It survived twice as long. Its temperature was less re-
duced, and its heart continued to act longer. Its lips, nose, and toes, became
of a florid colour.
NOTES. 475
A few experiments on the immersion of kittens seven day sold in
xoater of different temperature. Made 2Sth August, 1832.
By T. Nunnelly.
With water pumped up from the well at 57° Fahr.
No. 1. Struggled hard for a minute, when it apparently became insensible
and passed the faeces ; it exspired frequently and made violent attempts to inspire.
Some involuntary motion was continued for two minutes and a half, when it was
taken out, wiped dry, and placed before the fire at a temperature of about 80 ;
it heated immediately and quickly recovered.
No. 2. Allowed to remain in the water four minutes ; the effects were the
same as in No. 1, except that it did not completely recover so soon.
No. 3. Allowed to remain under the water for five minutes ; during the last
minute the involuntary motion was very slight, when taken out, breathed, and
recovered in fifteen minutes.
No. 4. Allowed to remain under water for six minutes ; this kitten did not
breathe for thirty seconds after being taken out, and was half an hour before
completely recovering.
No. 5. Allowed to remain under water for ten minutes ; for seven minutes
and a half some very feeble involuntary motion could be seen, but not more than
three minutes after the fifth minute. When taken out it was apparently quite
dead. I opened the trachaea, and continued artificial respiration for ten minutes
before it made any effort to respire, which for half an hour was very feeble ; for
an hour it lay in a comatose state, after which it gradually recovered, and in
four hours looked much as the other kittens. 1 allowed it to live for two days,
when 1 destroyed it, as of course it was unable to suck owing to the opening in
the trachaea.
With water at 100° Fahr.
No. 1 , 2, 3. Effects much the same as with water at a temperature of 57°F.
No. 4. Remained under water six minutes ; this kitten recovered, but was
a longer time than that with the water at 57°, and lay for an hour as though
asleep without moving, unless disturbed.
No. 5. Allowed to remain under water for ten minutes ; motion was per-
ceived for a longer time than in the similar experiment with water at 57°, viz.
for nine minutes. When taken out it was quite dead. Dry heat was applied,
the trachaea opened, and artificial respiration continued for an hour without
success.
Water at 120° Fahr.
No. 1. Allowed to remain under the water for five minutes ; it struggled hard
as the others did for a minute, and involuntary motion could be seen for four
minutes. When taken out, it was quite dead, and although precisely the same
means weie adopted as with the other cases, they were without success.
476 NOTES.
In all the kittens that recovered, in proportion to the time they had been under
water, was the breathing at the first slow, it then became exceedingly quick and
short, and it was some time before they regained their ordinary temperatures,
quite as long, or rather longer, after the warm medium, as after the colder.
Thomas Nunnelly.
PART IV.
CHAPTER II.
Since the publication of Dr. Edwards's observations respecting the heat of young
animals, some interesting researches have been made by his brother, Dr. Milne
Edwards, in conjunction with Dr. Villerme. They not only prove the inferiority
of the infant's power of resisting cold, but show in a forcible and striking manner,
the great practical importance of bearing this fact in mind. It is the custom in
France to convey infants, within a few hours of their birth, to the office of the mayor
of the quarter in which the nativity took place, in order that the birth may be re-
gistered, and the child become posssessed of its civil rights. A careful compa-
rison of the register of births, with the register of deaths, furnished statistical ob-
servations on so large a scale, that there can be no room to doubt the correctness
of the results. It appeared that the proportion of deaths, within a very limited
period after birth, compared with the total births, was much greater in winter
than in summer, and that this difference of proportion, was much greater in the
northern and colder departments, than in the southern and warmer. The details
of this investigation are recorded in a paper which the Doctors have presented to the
Institute. They have since continued the inquiry, and the following extract from
a letter which I have received from Dr. Milne Edwards, will show the accord-
ance of their results.
' ' In order to ascertain in a more positive manner than before, whether the mor-
tality of new born children is increased by their being carried to the maire im-
mediately after birth, we obtained from the minister of the interior, necessary
orders to have the tables of mortality of infants made in a certain number of
parishes, where the inhabitants are scattered over a larger surface of ground ; and
in others, where they are, on the contrary, agglomerated around the maire. It
appeared evident to us, that if our opinion was correct, the increase of mortality
during winters, must be much greater in the former parishes than in the latter,
and such is, indeed, the result actually afforded by our tables."
CHAPTER IX.
I have received the following letter on the subject of cutaneous absorption, of
which Dr. Edwards is a decided advocate, and, although, it combats the Doc-
tor's opinions, I am induced to publish it, not only because the author, Dr.
Corden Thompson of Sheffield, is an extremely well-informed physician, tho-
NOTES. 477
roughly versed in physiological reasoning and experiment, on which account his
opinion is entitled to respect ; but also, because it affords me an opportunity of
meeting similar objections, which may be urged by others, against the conclusions
maintained by Dr. Edwards, upon this subject.
" At the commencement of his observations on cutaneous absorption, Dr. Ed-
wards states, that from comparative essays made in air and water, Seguin thought
himself justified in concluding, that the latter fluid was not absorbed. But, he
continues, ' the result of these experiments admits of being viewed in a different
light, when we consider certain facts relative to the animal creation.' ' We have
seen,' he observes, ' that the batrachia are capable of imbibing, by their ex-
ternal surface, a considerable quantity of water, which passes into the system at
large. In such animals, as well as in man, the skin is bare, a condition highly
favourable to absorption. The human skin, it is true, from the nature of its
cuticle, is less fitted for performing this function, though it continues to exercise
it in a high degree.' Such is the language of Dr. Edwards. Now, in the first
place, I cannot, for a moment, admit the correctness of the analogy, here as-
sumed, betwixt the exterior surface of the batrachia, and that of man. The
former approaches the nature of mucous membrane, the absorbing faculties of
which, no one for a moment questions ; but, the latter, is essentially modified by
the dry superjacent cuticle, which, even the Doctor confesses, is less fitted for
for absorbing. To infer from mere analogy, that because the one takes up sub-
stances, therefore the other does, is in reality to take for granted, the very thing
which ought to be proved. The analogy, in fine, is incomplete ; the anatomical
elements of comparison are not the same in each case ; neither are the functions
of the structures in question the same. Pursuing, however, a similar, and I
should say, illusive mode of argument, we are told that it becomes impossible to
entertain further doubts on the subject, when we witness what occurs in animals,
the teguments of which, appear the least susceptible of transmitting fluids. Lizards,
for example, possess, as all know, a hard scaly exterior, which should seem an
effectual barrier to the passage of an aqueous fluid. Yet, could this he proved to
take place, our author imagined he would be justified in concluding a fortiori,
that a similar transmission exists in the human integuments. Hence, for the pur-
pose of determining that point, he confined an animal of this description in water,
in such a way, that the tail, posterior, extremities, and corresponding parts of
the body, were alone immersed. The lizard, moreover, in order to excite the
activity of the absorbents, had been previously kept in air for a few days ; its
weight being thus somewhat diminished, any subsequent increase would be ren-
dered more notable. At different intervals of time the animal was weighed ; and
the weight gradually augmented until the loss it had previously sustained was
restored. At this stage, the experiment was stopped, the Doctor being satisfied
with its result. I cannot, however, help thinking, that he has overlooked several
very important considerations ; considerations, which, to me, at least, seem alto-
gether to invalidate the conclusions drawn from this trial. In the first place, whe-
478 NOTES.
ther absorption by the skin do, or do not, exist, that by the lungs eannnot for a
moment be doubted ; neither can it be doubted, that it is of a most active and
energetic description. Now, here we have an animal confined mid-way in water,
in a glass tube, and surrounded therefore by a highly moist atmosphere, and yet
no notice whatever taken of pulmonary absorption ! This omission of itself is
fatal to the accuracy of the experiment. But, again ; if we revert to the nature
of the integuments, such an experiment, we shall see, is not calculated to set-
tle the point in question. The exterior covering of the body is an inorganic pro-
duction, and like similar substances, capable of mechanical imbibition, after con-
tinued maceration in a fluid. This is very easily observed in those parts of the
body where the cuticle is thick, as in the hands and feet. When thus saturated ,
it becomes white and wrinkled. In like manner, the inorganic tegument of the
lizard would doubtless absorb a portion of water, after considerable maceration in
that fluid, and thus the weight of the animal be increased, totally independent of
any absorption, into the interior of the system. Here, then, is another source of
fallacy. But, let us even suppose, after continued maceration of the integu-
ments in water, and after having thus been saturated, that eventually a portion
of the fluid finds its way into the system, would such an experiment warrant us
in concluding, that under any ordinary natural circumstances, any such thing
as cutaneous absorption exists 1 Surely not ; and I apprehend we shall find it to
be a frequent and radical error with experimentalists, to conduct their experi-
ments under highly unnatural circumstances, and to assign the result, thus ob-
tained, as a natural and ordinary function of the animal economy.
" If we except Seguin, whose admirable experiments on this subject most phy-
siologists are well acquainted with, Dr. Edwards does not notice any other writers,
or the facts which they adduce, in disproof of the doctrine which he maintains.
Seguin himself, indeed, obtains but a cursory glance; nor are his experiments
in any way refuted. Having established the existence of cutaneous absorption,
as he conceives, by the evidence already mentioned, Dr. Edwards next proceeds
to institute, what may be called, tare and tret computations, relative to the gain
or loss sustained by the body when immersed in water. And here again the ca-
pital oversight is committted, of neglecting to take pulmonary absorption into the
estimate. It is needless, therefore, to follow him in his observations on this part
of the subject. On the whole, the evidence from which Dr. Edwards seems to
infer the existence of cutaneous absorption, is either loose and vague on the one
hand, or manifestly fallacious on the other. The doctrine may be true ; but the
reasons here produced, are insufficient to substantiate it."
The principal objection advanced by Dr. Thompson, appears to rest on the
experiments of Seguin, and on the impediment, which he conceives, the epidermis
must oppose to absorption from the surface of the body. There can, indeed, be
no question as to the reality of the obstacle, but it is by no means evident, that
it is insurmountable. On the contrary, I think it most reasonable to infer, that
if this absorption, or imbibition, can take place through the dense and less per-
NOTES. 479
vious coverings of many reptiles, it must, notwithstanding Dr. Thompson's
objection, be admitted in the case of the human epidermis. There is an obvious
difficulty in bringing this question to the test of direct experiment, arising from the
fact, that exhalation, or transmission outwards, is unquestionably taking place,
and in general to a greater degree than we can even suspect it to take place in the
opposite direction. This very objection, however, furnishes us by analogy, with
one of the best arguments in favour of cutaneous absorption, since we have the
authority of several investigators, and more especially of Fodera and Dutrochet,
to prove that imbibition, and transudation, are reciprocal and simultaneous.
Dr. Thompson points to pulmonary absorption, as the cause to which the sup-
posed effects of cutaneous absorption ought to be ascribed. Many experiments,
but especially those of Meyer and Magendie, leave no room to doubt the activity
of the pulmonary absorption ; but, except under very extraordinary circumstances,
it does not seem probable that it can be exerted to any considerable extent, ex-
cept upon the secretions of the mucous membrane itself. It cannot, therefore,
be assigned as the inlet to any perceptible accession to the system. The fact,
that the expired air is much more charged with watery vapour, than that which
is inspired, tends to the same conclusion. If Dr. Edwards has omitted, as Dr.
Thompson remarks, to notice the statements of several authors, who have called
in question the reality of cutaneous absorption, he has likewise omitted to claim
the support of many who have sanctioned it, amongst whom might be mentioned
several of those who have written on the subject of diabetes.
Connection of rainy seasons with disease, exemplified in the
cases passing through an hospital.
There fell at the Havannah, in seven years, 603f French inches of rain, viz. in
1821, 131i inches; in 1822, 53^ inches ; in 1823, 100 inches ; in 1824,
79i inches; in 1825, 97 inches ; in 1826, 74 inches ; in 1827, 68^ inches.
The distribution per month, was as follows : — average for January, A\ inches ;
for February, 3 inches ; for March, 3± inches ; for April, 2\ inches ; for May,
9£ inches ; for June, 23| inches ; for July, 5^ inches ; for August, 6J inches ;
for September, 1 Of inches; for October, 10 1 inches; for November, 4| inches ;
for December, If inches.
From a corresponding table of 4028 sick, who passed through the Hospital, in
the course of seven years, it appears, that the months in which the sick exceeded
the monthly mean in number, were those from May to October inclusive, in
which, (with two exceptions) the rain was above the general monthly average
of seven inches. And the two exceptions lying between months which had rain
in excess, and following the highest amount of rain, (in June,) seem to be ac-
counted for on the principle, that disease may be continued by infection, after
the atmospherical predisposing causes have ceased to operate. Again, the years
in which the rain was above the annual mean of 76| inches, are mostly those in
which the sick exceeded the average annual number of 575 cases.
480 NOTES.
In both accounts the temperature is not to be left out of the question. The an-
nual mean, being 25'6° cent. ; that of the winter, is 21'8°; of the summer,
28*5°. The number of sick in seven years is, on an average for the winter, 218 ;
for the summer, 357. Yet it is not probable that heat alone, without the mois-
ture, would cause such a difference, but rather, that the summer would in that
case be the more healthy season. — Translated and abridged (with a remark an-
nexed by L. Howard) from Bibliotheque Universelle, 16me annee, p. 33.
Although it can scarcely be supposed, that any slight addition to the weight
and pressure of the atmosphere can have any sensible effect on the animal eco-
nomy, seeing, that not only changes of this description frequently accompany
vicissitudes in the weather, without leading to any obvious consequences, and
that by ascending to considerable heights and by descending into mines, we may
greatly increase the extent of such changes with perfect impunity ; yet, I cannot
omit to notice a recent observation of Dr. Prout's, which seems to indicate, that
even a slight increase in the weight of the atmosphere, may be the concomitant,
if not the cause, of a highly deleterious influence. Dr. Prout had, foryears, been
in the habit of carefully examining the weight of the atmosphere, when, on the
breaking out of cholera, he noticed a slight, but sensible increase of its weight,
which maintained itself with constancy for six weeks, when circumstances oc-
curred to suspend the Doctor's observations. He does not attribute any morbid
influence to the mere increase of weight of the atmosphere, but rather regards this
as the consequence of a deleterious and heavy gaseous principle, diffused through
the lower regions of the atmosphere. For a detailed account of Dr. Prout's ex-
periments and opinions upon this subject, the reader is referred to his paper,
which is about to appear in the transactions of the British Association.
Those who descend to a considerable depth in diving bells, are subjected to the
greatest atmospheric pressure to which it is easy for man to expose himself; but its
effect is necessarily complicated with that of the deterioration, and want of motion
of the air. Notwithstanding these combined sources of inconvenience, it is well
known, that workmen may continue their operations, during several hours of the
day, at a depth of many feet. From personal experience of the effects of this
situation, during about half-an-hour, I may state, that the only painful sensa-
tion is that occasioned by the pressure on the membrane of the tympanum, which
is felt on first descending ; but soon ceases, when the equilibrium between the in-
terior and exterior of the body is restored. The blood is very much driven from
the surface of the body, producing in general extreme paleness. When the su-
perficial capillaries are not emptied, which I observed to be the case with one
individual, who had, what is styled a fixed colour in his face, they become com-
pletely livid. According to the theory of Dr. Holland, the production of heat
ought to be reduced nearly to its minimum, since the proportion of the blood in
the lungs to that of the inspired oxygen must be great. The heat, however, be-
comes oppressive. It seems by no means improbable, that increased pressure of
the atmosphere may be one of the causes requiring the exercise of the function,
which I have ascribed to the spleen.
NOTES. 481
CHAPTER XVI.
la considering the observations of Dr. Edwards on the changes of the air in
respiration, there are two points which appear to be particularly interesting and
worthy of attention. The experimenters who have succeeded him had arrived at
different conclusions, more especially with respect to the consumption of oxygen,
and the alterations in the quantity of nitrogen. As these differences could not
be attributed to errors of observation, they tended to render the subject more
complex and puzzling, until Dr. Edwards, by instituting a series of experiments,
continued through the different seasons of the year, at once confirmed and ex-
plained the discrepancies of his predecessors, and made a valuable discovery res-
pecting the influence of climate andseason. The other point towhichl have alluded,
refers to the part of the body in which the changes in the respired air are effected.
It had been a subject of question, whether the carbonic acid expired, was not
formed immediately in the lungs, by the combination of the oxygen of the atmo-
sphere with the carbon of the venous blood. According to another view, it was
supposed that whilst a portion of the oxygen of the atmosphere was taken up by
the blood, and carried with it in its circulation, and at the same time carbonic
acid was thrown off from the lungs, having been previously taken up in the course
of the circulation. Dr. Edwards appears to have settled this question, which
seemed previously to be nearly balanced, by confirming the latter view. We have,
therefore, in the function of respiration, not only a striking instance of the transu-
dation, and imbibition of the gases through the membrane, but also of their
simultaneous passage in different directions. In both of these respects, Dr. Ed-
wards has anticipated Fodera and Dutrochet, whose observations have further
elucidated them, and pointed out analogous phaenomena in other parts and func-
tions. Since the publication of Dr. Edwards's work, some further experiments
on respiration have been performed by those careful and accurate operators, my
friend William Allen, and his associate, W. H. Pepys ; and others of equal
interest, by my friend S. Broughton. Before I notice the facts, which these ex-
perimenters have either confirmed or added, it appears necessary that I should
notice the discoveries and views of Dr. Stevens, which throw the most important
light on the process of respiration. These views were not the offspring of specu-
lation, which he has sought to confirm by subsequent experiments, but they forced
themselves upon him, whilst he was investigating the changes of the blood, and
the phsenomena of fever ; and it seems necessary that I should remark, to set
aside any prejudice which may exist in the mind of the reader, that the Doctor's
physiological observations respecting respiration, stand upon their own distinct
merits, and are by no means compromised by his pathological and therapeutical
doctrines. In order to keep the subjects distinct, I purposely refrain from offer-
ing an opinion respecting the last mentioned points ; yet, I cannot withhold the
expression of my admiration of the zeal, perseverance, and self-devotion, with
which the Doctor has pursued his investigations respecting them, under the most
I I
482 NOTES.
arduous, and, perhaps, perilous circumstances. One of the most striking facts
which the Doctor has brought into notice, is the powerful attraction which exists
between oxygen and carbonic acid. It was so fully admitted amongst chemists,
that carbon in carbonic acid is united with its maximum dose of oxygen, that the
idea of attraction between carbonic acid and oxygen was rejected from a priori
reasoning by several able chemists, to whom the Doctor mentioned the subject.
The fact, however, is clearly proved by the experiments of Dr. Stevens. If a
receiver filled with carbonic acid, and closed by a piece of bladder firmly tied
over it, be exposed to the atmospheric air, the carbonic acid, notwithstanding its
superior specific gravity, rapidly escapes, and does so without the exchange of an
equivalent portion of atmospheric air ; the bladder is consequently forcibly de-
pressed into the receiver. If the converse of this experiment be tried, and the re-
ceiver, containing atmospheric air be tied over with a piece of bladder, or thin
leather, and then be immersed in carbonic acid, this gas will so abundantly pe-
netrate the membrane, and enter the receiver, as to endanger its bursting.
Dr. Stevens had repeated opportunities of verifying these facts, during a stay
which he made at Saratoga, in the United States ; the springs at which place
liberate a large quantity of carbonic acid. In the high rocks it often collects in
considerable quantity and purity, and experiments on dogs and rabbits are often
made for the entertainment of strangers, as at the Grotto del Cane, near Naples.
This rock stands by itself in a low valley, through which there run two currents of
water, the one fresh and superficial, the other beneath, and charged with salts
and carbonic acid. A current of this water rises to some height in a cavity of the
high rock, which appears to have been formed by a deposition of earthy salts
from the water. It has a conical figure, the base of which, is below the surface of
the ground, is about nine feet in diameter. It rises about five feet from the ground,
where it is truncated, and presents an aperture a foot in diameter. The cavity
of this rock is conical, like its external figure — the water appears formerly to have
overflowed the summit, but it now rises in general only about two feet above the
ground. In the three feet above, the liberated carbonic acid collects, but it varies
very much, both in quantity and purity, notwithstanding the sides of the rock are
thick and impervious, and the superior specific gravity of the gas, which is con-
stantly liberated in large quantity. The removal of the carbonic acid appears to
be effected by virtue of that attraction, which Dr. Stevens has pointed out as exist-
ing between it, and the oxygen of the atmosphere. When the air is somewhat
agitated by wind, a taper will burn in the cavity of the rock, almost as low as the
surface of the water ; but when the air is calm, the taper is extinguished much
nearer the top of the rock. By luting a large funnel over the aperture, so as to
exclude the influence of the air, the rock became filled with carbonic acid, which
the Doctor collected for his experiments, at the mouth of the funnel. Dr. Stevens
took advantage of the facilities afforded by this rock, to multiply and vary his ex-
periments, the results of which, were not only perfectly satisfactory to himself,
but to many individuals to whom he exhibited them. This attraction, which the
NOTES. 483
Doctor has pointed out, is not only to be regarded as an important agent in the
function of respiration, but throws considerable light on the constitution of the
atmosphere, since it accounts for carbonic acid, notwithstanding its greater spe-
cific gravity being found in equal proportions at every elevation to which we can
ascend, instead of being collected at or near the surface of the earth.
Experiments similar to those of Dr. Stevens, and attended with the same re-
sults, have been published in an American Journal, by Drs. Faust and Mitchell,
who have anticipated Dr. Stevens, in committing them to the press, without mak-
iug any allusion to his discovery, although there can be but little doubt but they
were in a degree acquainted with it, as the Doctor himself had related the re-
sult of his previous experiments, not only to other professional individuals in the
United States, but even to the very editor of the Journal in which the American
papers were first published. It is stated also, that this gentleman took a part in
Dr. Mitchell's experiments. Dr. Stevens formed his views, respecting the attrac-
tion of the atmosphere for carbonic acid, and committed them to paper, in 1827,
at which time, he resided in the West Indies. In 1828, they were mentioned,
or shewn in manuscript, to several persons in this country : and in France, which
the Doctor visited in 1829, more than one chemical philosopher was disposed
to dispute the existence of such an attraction — Dr. Edwards himself was amongst
this number.
Dr. Stevens went to the United States in 1830, in the seventh month (July).
The American experiments commenced soon after, and were published be-
fore the end of the year. The reader, I trust, will allow the excellence of the
principle, suum cuique, to be a sufficient apology for the introduction of this
statement.
Although this mutual influence, between carbonic acid and oxygen, may not
now be doubted, yet different views may be entertained respecting its nature.
The views and discoveries of Dalton, respecting the admixture of gases and va-
peurs, appear to bear the closest relation to this subject, but they do not seem to
be adequate for the explanation of all the phaenomena. Although the particles of a
particular gas, or vapour, may repel each other, yet allow those of a different gas,
or vapour, to come between them, and thus allow, what Dr. Mitchell styles, the
penetrativeness of one and the elasticity of another gas, to promote their inter-
mixture ; yet, it is not very evident, that this theory can explain their energetic
union, when a membranous septum has been interposed between them, and still
less, why carbonic acid should be so much more powerfully brought into ad-
mixture with oxygen, than with nitrogen, or hydrogen, which are much rarer
gases.
It has been supposed, that the phaenomena pointed out by Dr. Stevens, are
■ of the same nature with those which Dutrochet has described under the terms,
endosmosis and esosmosis, but unless we are to regard every instance, in which
one fluid diffuses itself through another, or passes through a porous body, as an in-
stance of endosmosis, or exosmosis, an idea which Dutrochet himself would re-
i i2
484 NOTES.
ject — there is, notwithstanding, some analogy — a striking difference between
the phenomena in the cases of endosmosis related by Dutrochet ; the intervening
septum performs a very important part in influencing the movement of the fluids.
This is most strikingly exemplified in the application which he makes of his prin-
ciple to the circulation of the sap in the roots and branches of plants. In the
phaenomena pointed out by Dr. Stevens, the impulse resides in the gases them-
selves, and all we can say respecting the septum interposed between, is, that it
does not prevent their union.
Although Dr. Stevens informs us, that Dr. Edwards offered some objections
to his views, respecting the removal of carbonic acid from venous blood in the
lungs, by virtue of an attraction for that acid, inherent in the inspired air ; yet,
I must confess, that after a careful consideration of the subject, the views of
Dr. Stevens, instead of militating against the observations of Dr. Edwards, are
in the most satisfactory accordance with them.
In order to understand the application of the attraction pointed out by Dr. Ste-
vens to the function of respiration, it will be necessary to be aware of a few facts
relating to the blood ; some of these were more or less known prior to the expe-
riments of Dr. Stevens, but he has the merit of greatly extending, as well as ap-
plying them. All acids impart a dark colour to the blood. With respect to most
acids this colour remains, although the added acid be afterwards saturated. Car-
bonic acid forms an exception, for on the removal of this aerial acid the blood re-
sumes its bright and arterial colour. Alkalies, like acids, darken the colour of the
blood, but salts produce a bright and vermillion colour, when added to the colour-
ing matter of the blood. Thealkaline carbonates require particular notice. Theacid
is so feebly held by the base, that in some respects they conduct themselves as al-
kalies, and in particular, will restore the blue colour to reddened litmus. Dr.
Stevens believes that this circumstance has led some chemists of great celebrity,
to admit the presence of free alkali in the blood, whilst he takes an opposite view,
and believes that in venous blood at least, there is a superabundance of free car-
bonic acid, which, however, is soon removed by exposure to the air. This opinion
seems to be confirmed by the fact, that if water, holding carbonate of soda, and
carbonic acid in solution be added to the blood, a deep and venous hue is pro-
duced. After a short exposure to the air the carbonic acid is removed, as Dr.
Stevens believes, by the attraction already noticed, and the blood is reddened by
the carbonate of soda, the influence of which, is no longer controuled by the re-
dundant acid. The recently separated serum of venous blood has no effect on
turmeric paper, although it has after a little exposure to the air.
There are many other phaenomena connected with the blood which Dr. Stevens
has noticed ; for these, I must refer the reader to the Doctor's own interesting work.
Those which I have already mentioned, will suffice to enable us to appreciate the
light which the Doctor has thrown on the function of respiration. I must, how-
ever, take the liberty of remarking, with respect to the curious phaenomena he
observed with the help of a powerful solar microscope, that I believe some fallacy
NOTES. 485
attends them, in consequence of the heat unavoidably applied to the object, brought
into the field of the instrument in bright daylight. It will, I am sure, be under-
stood, that I am not invalidating the Doctor's evidence, when I ascribe many of
the globular appearances which came under his view, to the disengagement of
gases effected by the heat in question. The best compound achromatic micro-
scopes, not only possess a superior power, but are exempt from the objections
which I am now urging against the solar microscope. The account given in this
volume of the microscopic appearances of the blood, as seen through a compound
microscope of the highest quality, does not coincide with the description given
by Dr. Stevens. The explanation which I have offered, will, I believe, satis-
factorily account for the difference. Though I do not regard the microscopic
phaenomena, described by Dr. Stevens, as affording a correct view of the struc-
ture of the blood, I am not disposed to reject them, but rather to query, whether
they may not lead to some curious observations in the disengagement of gases
from fluids.
To return to the subject of respiration. The views of Dr. Stevens accord with
the opinions of those who reject the idea of the formation of carbonic acid as taking
place in the lungs, by the immediate union of the oxygen of the atmosphere with
the carbon contained in the venous blood. We have seen that Dr. Edwards is
of this number, inasmuch, as he believes, the formation of carbonic acid to take
place throughout the body. Dr. Stevens, however, does not regard the air as
passively receiving the carbonic acid as it is liberated from the blood, which had
not only held it in solution, but actually imbibed it. He considers that it is ac-
tively removed by the attraction existing between oxygen and carbonic acid,
which overcomes the weaker attraction by which the acid was united with the
blood. When the blood has lost its carbonic acid, it presents the bright Vermil-
lion tint which naturally belongs to its colouring matter, and salts, when com-
bined. When the venous blood gives up its carbonic acid, it receives in exchange,
a portion of the inspired air, which is chiefly at the expence of the oxygen. The
proportion of this gas, abstracted from the inspired air, being very nearly, and
often exactly, the same as that of the carbonic acid added to it, Dr. Edwards
has pointed out the circumstances under which the quantities differ. We must
not, however, suppose that it is only carbonic acid which is exhaled, or oxygen
which is received by the blood and lungs. The experiments of Allen and Pepys,
as well as those of Dr. Edwards, have proved that there is an interchange of
other gaseous principles. The reddened and oxygenated blood having returned
to the heart, is diffused over the system, imparting animal heat in proportion to
the quantity of oxygen which it gives up for the production of carbonic acid. It
receives this carbonic acid in exchange for the oxygen which it has lost, and is
darkened by its presence, which counteracts the effects of its salts. This, I be-
lieve to be a concise sketch of Dr. Stevens's theory of respiration ; it is far from
clashing with Dr. Edwards's observation respecting the disengagement of car-
bonic acid ; it seems, on the contrary, satisfactorily to account for cutaneous
486 NOTES.
respiration, since, wherever the atmosphere is exposed to a vascular part, its
oxygen must promote the separation of carbonic acid from the venous blood. If
we apply this view to the respiration of animals who live in water, and admit that
the oxygen dissolved in that fluid, separates carbonic acid from their venous
blood, we have another argument in favour of an actual attraction existing be-
tween oxygen and carbonic acid, since the discoveries of John Dalton, and the
penetrativeness of Dr. Mitchell, are quite inapplicable to the subject.
The experiments of Allen and Pepys to determine the changes produced in
the air by respiration, which have been made subsequent to the publication of
Dr. Edwards' work, are a continuation of their former researches, and were made
solely on the respiration of birds. These enquirers conducted their experiments
in the same method as that which they had formerly employed, and in no instance
compromised the life or health of the animal. The birds were placed in a small
glass chamber, which received its supply of air from one gasometer and parted
with it into another at certain intervals. The most careful analysis was made,
both of the gas supplied to the animal, and of that which it had respired ;
every calculation being made which the state of the barometer and thermometer,
and the volume of air existing in the receiver containing the bird, and the tubes
leading to it, could require ; their results may be stated as follow : —
After one hour and twelve minutes respiration, the amount of gasses employed
being originally oxygen azote carb acid.
Cubic inches ..245-59 61-41
There remained 195-61 90-11 21-27
shewing a loss of 28*71 of oxygen beyond the volume converted into carbonic
acid, and a gain of 28-70 of azote. The head and other parts of the pigeon
in which the state of its vessels could be seen, were of a bright red. In a similar
experiment which lasted one hour and ten minutes, 24-74 cubic inches of car-
bonic acid were produced, besides which, 21-75 of oxygen were lost. In atmo-
spheric air, 35-80 cubic inches of carbonic acid were produced in sixty-nine
minutes. In a mixture of oxygen and hydrogen with a portion of azote, a pigeon
in the course of twenty-six minutes, produced 17'62 cubic inches of carbonic
acid • 35-48 of hydrogen were lost, and 35-23 of azote were added.
Allen and Pepys were not acquainted with the researches of Dr. Edwards,
and as they inclined to the belief, that the volume of oxygen lost was replaced by
an equal volume of carbonic acid, their delicate and accurate experiments form a
valuable confirmation and supplement to those of the Doctor. The experiments
of S. D. Broughton, relate to the same subject, but were performed in a somewhat
different manner, and supply us with new and valuable facts. He placed a
variety of animals in receivers of considerable capacity compared with their bulk ;
he filled them with different gases, in which he allowed the animals to remain
until they were nearly or quite dead, when he examined their state and that of
the gas remaining in the receiver. His most important and numerous experi-
ments relate to the respiration of oxygen. He found, as Allen and Pepys had
NOTES. 487
done, that animals at first bear this kind of respiration with apparent impunity,
that the pure oxygen at first acts as a stimulus, and that all the parts of the
body in which the state of the vessels can be seen are injected with bright arterial
blood. Though this florid colour continues, the powers of the animal progres-
sively sink, he falls into a state of suspended animation, and inevitably dies in
the couise of a few hours if suffered to remain in the gas ; and even if taken out
alive, the injury which he has received may be fatal. This effect is not to be
ascribed to the deterioration of the air in the receiver, as in the case of an
animal dying in a given quantity of atmospheric air. The remai.iing oxygen
is still sufficiently pure to support the vivid combustion of iron-wire, and to
produce a repetition of effects on a second and third animal similar to those
described as occurring with the first. The animal is found to have all its
sanguiferous vessels filled with bright arterial blood, and its temperature is
found to have fallen several degrees, even when taken out before life is
extinct. The fatal effects of the respiration of pure oxygen gas are con-
firmed by the experiments of Sir H. Davy, and by those of Drs. Prout and Ma-
gendie. The blood is observed quickly to coagulate after the respiration of this
gas. S. D. Broughton tried the effects of the gaseous oxide of nitrogen, com-
monly known as the exhilarating gas ; this can be respired longer than other
gases, yet death takes place sooner than in pure oxygen. The blood continues
fluid and thin. He found animals die very quickly in sulphuretted hydrogen ;
indeed it is impossible to conceive death more instantaneous than that which I
have myself seen take place in a sparrow, which Professor Thenard introduced
into this gas. This effect of sulphuretted hydrogen, appears to have been known
to the ancients long before chemistry existed as a science, as may be inferred
from the expression, graveolens aornus, employed by Virgil, as well as from
some remarks of Pliny, respecting a fountain not far from Rome. He found
carbonic oxide, though a fatal gas, to be less promptly so than sulphuretted
hydrogen ; and it is worthy of remark, that the interior of animals killed by it,
was not only gorged with venous blood, but seemed unusually hot. The results
of the preceding experiments, together with some others detailed in this volume,
suggest the following observations : —
We have seen that Dr. Holland has objected to the theory maintained by Dr.
Edwards, that the amount of animal heat is in proportion to the consumption of
oxygen, and endeavours to substitute in its place, that it is in the inverse ratio
of the quantity of the blood to the inspired air. It is evident from Dr. Edwards's
own words, that by the consumption of oxygen, he means its conversion into
carbonic acid, since he admits the absorption of this gas during summer, when
even adult animals are considered by him, to lose a part of their power of pro-
ducing heat.
The researches of Broughton have shewn, that when animals inspire this gas in
its pure state, they sink in temperature ; and the experiments of Allen and Pepys
have shewn, that a larger quantity of this gas is consumed than is replaced by
/
488 NOTES.
carbonic acid, the production of which, is diminished. It is also remarked, that
those external parts, in which we can observe the state of the circulation, become
manifestly injected ; hence we must have that condition of the circulation, which
Dr. Holland regards as the most favourable for the production of animal heat ;
yet we have seen that the results alluded to oppose this conclusion. T am in-
clined to believe, that the production of animal heat bears a close and necessary
relation to the quantity of carbonic acid produced. I agree so far with Dr. Hol-
land as to believe, that when the lungs are greatly loaded with blood, the changes
in it effected by the air are impeded, and that the temperature may sink ; but
this I conceive to be the consequence of the diminished production of carbonic
acid. On the other hand, the effects of pure oxygen evince a striking difference
between animal heat, and that of ordinary combustion. The carbonic ; cid by
which the blood is darkened, is strikingly removed ; but contrary to w! . one
would have suspected, a priori, its further production is impeded : hen , not
only the diminution of temperature, but also, the universal redness of the blood.
It has been shewn by some of the experiments of Sir Astley Cooper already re-
lated, that immersion in ice-cold water, had the effect of inducing a singularly
bright arterial colour in those parts in which the blood is collected. This effect,
like that of animals dying in oxygen gas, was more to be ascribed to the sus-
pended carbonization, than to the increased decarbonization of the blood.
Without attempting to draw any express conclusions from the experiments of
Dr. Edwards, with reference to temperature, season, and age, beyond those
which the Doctor has himself offered, I cannot refrain from remarking, that
there is no part of the Doctor's work which possesses greater practical importance
and utility. In conjunction with the researches of Dr. Curry of Liverpool, they
will afford the most valuable assistance in the regulation of clothing, of exposure
to the open air, of confinement within doors, and of the application of the various
forms of baths.
PRINTED BY STEWART AND CO., OLD BAILEY.
f X*-
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