Produced by Sonya Schermann, John Campbell and the Online
Distributed Proofreading Team at http://www.pgdp.net (This
file was produced from images generously made available
by The Internet Archive)
TRANSCRIBER’S NOTE
Italic text is denoted by _underscores_.
Footnote anchors are denoted by [number], and the footnotes have been
placed at the end of each chapter that has footnotes. Several are very
long.
Some minor changes are noted at the end of the book.
PHYSIOLOGICAL RESEARCHES
ON
LIFE AND DEATH,
BY XAVIER BICHAT;
Translated from the French,
BY F. GOLD,
MEMBER OF THE ROYAL COLLEGE OF SURGEONS, LONDON:
WITH NOTES,
BY F. MAGENDIE,
Member of the Institute and of the Royal Academy of Medicine.
_THE NOTES TRANSLATED_
BY GEORGE HAYWARD, M. D.
BOSTON:
PUBLISHED BY RICHARDSON AND LORD.
J. H. A. FROST, PRINTER.
1827.
DISTRICT OF MASSACHUSETTS: _to wit_.
_District Clerk’s Office._
BE IT REMEMBERED, That on the seventeenth day of December, A. D.
1827, in the fifty-second year of the Independence of the United
States of America, RICHARDSON & LORD, of the said District, have
deposited in this office the title of a book, the right whereof
they claim as proprietors, in the words following, _to wit_:
“Physiological Researches on Life and Death, by Xavier Bichat;
translated from the French, by F. Gold, member of the Royal
College of Surgeons, London, with notes, by F. Magendie, member
of the Institute and of the Royal Academy of Medicine. The notes
translated by George Hayward, M. D.”
In conformity to the Act of the Congress of the United States,
entitled, “An Act for the encouragement of Learning, by securing
the copies of Maps, Charts and Books, to the Authors and
Proprietors of such Copies, during the times therein mentioned:”
and also to an Act entitled, “An Act supplementary to an Act,
entitled, An Act for the encouragement of Learning, by securing the
Copies of Maps, Charts and Books, to the Authors and Proprietors of
such Copies during the times therein mentioned; and extending the
benefits thereof to the Arts of Designing, Engraving and Etching
Historical and other Prints.”
JOHN W. DAVIS,
_Clerk of the District of Massachusetts_
TRANSLATOR’S PREFACE.
The Translator of the Work which is here offered to the Public,
feels it quite unnecessary to expatiate upon the merits of its
Author, whose ideas and classifications in Physiology are now
very generally adopted. He has supposed, however, that the
experiments which constitute the _Second_ Part of the Work, are
not so familiar to Professional Men, as many of the conclusions
which have been deduced from them, and therefore has presumed
that a greater publicity of these experiments will by no means be
unserviceable. Dr. Kentish, in his account of Baths, has mentioned
the circumstances which led to this translation.
ADVERTISEMENT BY THE FRENCH EDITOR.
The work of Bichat, which appears to the most advantage, is the
one that we now reprint; his observing mind, his experimental
genius and his lucid manner of exhibiting facts are particularly
observable in it. This work will have for a very long time a great
influence on physiologists and physicians.
The Physiological Researches on Life and Death have had more
than one class of admirers. Exact minds, friends of the progress
of science have praised it for the great number of accurate
observations which it contains, the ingenious management of the
experiments and the correctness of the deductions; but they have
regretted that the author constantly placed life in opposition to
physical laws, as if living beings were not bodies before they were
vegetables or animals. They have seen with regret that he offered
illusory explanations of inexplicable phenomena.
These grounds of legitimate criticism seem to have been the reason
of the enthusiasm of another class of readers, for whom whatever is
vague appears to have a great degree of attraction. The readers,
of whom I have just spoken, feeling but little interest in the new
facts which the Physiological Researches contain, have adopted
without examination its fallacious hypotheses, and attaching
to them an importance which the author never did, because they
believed that they elucidated the mechanism of the most obscure
vital operations, and conducted to a true theory of medicine.
Should we lament this errour? Certainly not, as it has powerfully
contributed to the brilliant success of Bichat’s work, and by means
of some errours, much truth has been promulgated.
As the works of Bichat have now become classics and their
reputation cannot be increased, it is time to place young students
on their guard against the errours into which the imagination of
the author led him, and which are the more to be feared, as Bichat
in order to convince, has employed all the fascinations of his
animated style.
The memory of Bichat cannot but gain by it; the numerous truths
which he has discovered will shine with a brighter light, when
freed from the light shades that envelope them.
Such is the object of the notes to the present edition, which we
have endeavoured to bring up to the present state of knowledge.
CONTENTS OF THE WORK.
PART THE FIRST.
CHAPTER I.
Page
Division of Life into Animal and Organic Life 11
CHAPTER II.
General Differences of the two Lives, with regard to the outward
form of their respective Organs 18
CHAPTER III.
General Differences of the two Lives, with regard to the mode of
action of their respective Organs 25
CHAPTER IV.
General Differences of the two Lives with respect to Duration of
Action 40
CHAPTER V.
General Differences of the two Lives with respect to Habit 46
CHAPTER VI.
General Differences of the two Lives with respect to Mental
Affection 54
CHAPTER VII.
General Differences of the two Lives with respect to Vital Power 76
CHAPTER VIII.
Of the Origin and Development of the Animal Life 132
CHAPTER IX.
Of the Origin and Development of the Organic Life 156
CHAPTER X.
Of the Natural Termination of the Two Lives 163
PART THE SECOND.
CHAPTER I.
Page
General Considerations on Death 173
CHAPTER II.
Of the Influence of the Death of the Heart over that of the Brain 176
CHAPTER III.
Of the Influence of the Death of the Heart over that of the Lungs 192
CHAPTER IV.
Of the Influence of the Death of the Heart over that of all the
Organs 194
CHAPTER V.
Of the Influence of the Death of the Heart, as to the production
of General Death 202
CHAPTER VI.
Of the Influence of the Death of the Lungs over that of the Heart 210
CHAPTER VII.
Of the Influence of the Death of the Lungs over that of the Brain 237
CHAPTER VIII.
Of the Influence of the Death of the Lungs over that of the
Organs in general 252
CHAPTER IX.
Of the Influence of the Death of the Lungs over the General Death
of the Body 276
CHAPTER X.
Of the Influence of the Death of the Brain over that of the Lungs 297
CHAPTER XI.
Of the Influence of the Death of the Brain over that of the Heart 305
CHAPTER XII.
Of the Influence of the Death of the Brain over that of all the
Organs 318
CHAPTER XIII.
Of the Influence of the Death of the Brain over that of the Body
in General 332
PHYSIOLOGICAL RESEARCHES
ON
LIFE AND DEATH.
PART THE FIRST.
CHAPTER I.
GENERAL DIVISION OF LIFE.[1]
The definition of life is usually sought for in abstract
considerations; it will be found, if I mistake not, in the
following general expression:--Life consists in the sum of the
functions, by which death is resisted.[2]
In living bodies, such in fact is the mode of existence, that
whatever surrounds them, tends to their destruction. They are
influenced incessantly by inorganic bodies; they exercise
themselves, the one upon the other, as constant an action; under
such circumstances they could not long subsist, were they not
possessed in themselves of a permanent principle of reaction. This
principle is that of life; unknown in its nature, it can be only
appreciated by its phenomena: an habitual alternation of action
and reaction between exterior bodies, and the living body, an
alternation, of which the proportions vary according to the age of
the latter, is the most general of these phenomena.
There is a superabundance of life in the child: In the child, the
reaction of the system is superior to the action, which is made
upon it from without. In the adult, action and reaction are on
a balance; the turgescence of life is gone. In the old man, the
reaction of the inward principle is lessened, the action from
without remaining unaltered; it is then that life languishes, and
insensibly advances towards its natural term, which ensues when all
proportion ceases.
The measure, then, of life in general, is the difference which
exists between the effort of exterior power, and that of interior
resistance. The excess of the former is an indication of its
weakness; the predominance of the latter an index of its force.
I. _Division of Life into Animal and Organic Life._[3]
Such is life considered in the aggregate; examined more in detail
it offers us two remarkable modifications, the one common to the
vegetable and the animal; the other belonging exclusively to
the latter. In comparing two individuals from each of the living
kingdoms, the one will be seen existing only within itself, having
with what surrounds it the relations only of nutrition, attached to
the soil, in which its seed has been implanted, born there, growing
there, and perishing there. The other will be observed combining
with this interior life, which in the highest degree it enjoys,
an exterior life by which it acquires a very numerous series of
relations with all surrounding bodies, a life, which couples it to
the existence of every other being, by which it is approximated, or
removed from the objects of its desires or its fears, and seems in
appropriating every thing in nature to itself, to consider every
thing with regard to its individual existence only.[4]
Thus it might be said, that the vegetable is only the sketch, or
rather the ground-work of the animal; that for the formation of the
latter, it has only been requisite to clothe the former with an
apparatus of external organs, by which it might be connected with
external objects.
From hence it follows, that the functions of the animal are of
two very different classes. By the one (which is composed of an
habitual succession of assimilation and excretion) it lives within
itself, transforms into its proper substance the particles of
other bodies, and afterwards rejects them when they are become
heterogeneous to its nature. By the other, it lives externally, is
the inhabitant of the world, and not as the vegetable of a spot
only; it feels, it perceives, it reflects on its sensations, it
moves according to their influence, and frequently is enabled to
communicate by its voice its desires, and its fears, its pleasures,
and its pains.
The aggregate of the functions of the first order, I shall name
the organic life, because all organized beings, whether animal or
vegetable, enjoy it more or less, because organic texture is the
sole condition necessary to its existence. The sum of the functions
of the second class, because it is exclusively the property of the
animal, I shall denominate the animal life.
The series of the phenomena of these two lives, relate to the
individual. Generation, as a function, regards the species, and
thus has no place among them. Its connections with the greater
number of the other functions are but very indirect; it commences a
long time after them, it is extinct a long time before them. In the
greater number of animals the periods of its activity are separated
by long intervals of time, and during these, it is absolutely null.
Even in man, with whom the remissions of its impulses, are much
less durable, it has not a much more extensive connexion with the
rest of the system. Castration is almost always marked by a general
increase of the nutritive process; the eunuch, enjoying indeed a
less degree of vital energy, but the phenomena of his life being
displayed with a greater exuberance. We shall here, then, lay aside
the consideration of the laws which give us existence, and occupy
ourselves alone on those which maintain us in existence. Of the
former we shall speak hereafter.
II. _Subdivision of each of the two lives into two orders of
functions._
The animal and the organic life, are each of them composed of two
orders of functions, which succeed each other, and are concatenated
in an inverse direction.
In the animal life, the first order is established from the
exterior of the body, towards the brain; the second from the brain
towards the organs of locomotion and the voice. The impression of
objects successively affects the senses, the nerves and the brain.
The first receive, the second transmit, the third perceives the
impression. The impression, in such way, received, transmitted, and
perceived, constitutes sensation.
The animal, in the first order of these functions, is almost
passive; in the second, he becomes active.--This second order is
the result of the successive actions of the brain (where volition
has been produced in consequence of the previous sensation) of the
nerves, which transmit such volition, and of the locomotive organs
and voice, which are the agents of volition. External bodies act
upon the animal by means of the first order of these functions, the
animal reacts upon them by means of the second.
In general there exists between the two orders a rigorous
proportion; where the one is very marked, the other is put forth
with energy. In the series of living beings, the animal, which
feels the most, moves also the most. The age of lively perception,
is that also of vivacity of motion; in sleep, where the first
order is suspended, the second ceases, or is exercised only
with irregularity. The blind man, who is but half alive to what
surrounds him, moves also with a tardiness which would very soon be
lost, where his exterior communications to be enlarged.
A double movement is also exercised in the organic life; the one
composes, the other decomposes the animal. Such is the mode of
existence in the living body, that what it was at one time it
ceases to be at another. Its organization remains unaltered, but
its elements vary every moment. The molecules of its nutrition by
turns absorbed and rejected, from the animal pass to the plant,
from the plant to inorganic matter, return to the animal, and so
proceed in an endless revolution.
To such revolution the organic life is well adapted. One order
of its functions assimilates to the animal the substances which
are destined to nourish him; another order deprives him of these
substances, when, after having for some time made a part of it,
they are become heterogeneous to his organization.
The first, which is that of assimilation, results from the
functions of digestion, circulation, respiration, and nutrition.
Every particle, which is foreign to the body before it becomes an
element of it, is subject to the influence of these four functions.
When it has afterwards concurred for some time to the formation of
the organs, the absorbents seize on it, and throw it out into the
circulatory torrent, where it is carried on anew, and from whence
it issues by the pulmonary or cutaneous exhalations, or by the
different secretions by which the fluids are ejected from the body.
The second order, then, of the functions of the organic life,
or that of decomposition, is formed of those of absorption,
circulation, exhalation, and secretion.
The sanguiferous system, in consequence, is a middle system, the
centre of the organic life, as the brain is the centre of the
animal life. In this system the particles, which are about to be
assimilated, are circulated and intermixed with those, which having
been already assimilated, are destined to be rejected; so that
the blood itself is a fluid composed of two parts; the one, the
pabulum of all the parts of the body, and derived from the aliment;
the other, excrementitious, composed of the wrecks and residue
of the organs, and the source of the exterior secretions and
exhalations.--Nevertheless these latter functions serve also, at
times, the purpose of transmitting without the body, the products
of digestion, although such products may not have concurred to the
nourishments of the parts. This circumstance may be observed when
urine and sweat are secreted after copious drinking. The skin and
the kidneys being at such times the excreting organs, not of the
matter of the nutritive, but of that of the digestive process; the
same also may be said of the milk of animals, for this is a fluid
which certainly has never been assimilated.[5]
There does not exist between the two orders of the functions of the
organic life the same relation, which takes place between those
of the animal life. The weakness of the first by no means renders
absolutely necessary a decrease of action in the second. Hence
proceed marasmus and leanness, states, in which the assimilating
process ceases in part, the process of excretion remaining
unaltered.
Let us leave, then, to other sciences, all artificial method, but
follow the concatenation of the phenomena of life, for connecting
the ideas which we form of them, and we shall perceive, that the
greater part of the present physiological divisions, afford us but
uncertain bases for the support of any thing like a solid edifice
of science.
These divisions I shall not recapitulate; the best method of
demonstrating their inutility will be, if I mistake not, to prove
the solidity of the division, which I have adopted. We shall now
examine the great differences, which separate the animal existing
without, from the animal existing within, and wearing itself away
in a continual vicissitude of assimilation and excretion.
FOOTNOTES:
[1] The form adopted by Bichat, in this work, has been much blamed
by some, and extravagantly praised by others. The blame and the
praise appear to me to be equally misplaced. His object was to
exhibit the various phenomena of life; the order in which this
was to be done was a matter of indifference. If Bichat gave a
preference to this form, it was because it was conformable to the
nature of his mind; and he accomplished his task in a very happy
manner. The division that he has adopted is not new, it may be
found, with slight modifications, in writers of different periods,
and even in Aristotle. Besides, it is not necessary in the sciences
to attach a very great importance to classification. All these
contrivances have been invented only to aid the memory; and the
functions of living bodies are not so numerous, as to render it
necessary in studying them to lean upon systematic divisions.
[2] The word _life_ has been employed by physiologists in two
different senses. With some, it means an imaginary being, the sole
principle of all the functions which living bodies exhibit; with
others, it means only the assemblage of these functions. It is
in this last sense that Bichat employs it. This is what he means
to say in the following sentence. _Life is the assemblage of the
functions which resist death._ He is wrong only in allowing the
idea of death to enter into it; for this idea necessarily supposes
that of life. There is then really a bad circle in this definition;
but in putting aside what is defective in the expression, it may be
seen that Bichat considers life as a result, not as a cause.
Before and since the time of Bichat, a great number of definitions
of life has been given, which are either false or incomplete. It
should not be required of a definition, that it should give all
the properties of the thing which it is designed to make known,
this would be a description; but we have a right to expect that it
should assign to this thing certain characters which belong to it
alone, and thus distinguish it from every thing else.
Let us examine by this principle the definition adopted in a modern
work. _Life_, it is said, _is the assemblage of the phenomena which
succeed each other, for a limited time, in an organized being_.
This is no doubt true of life; but, if it can also be applied to
another state, it ceases to be a definition. An animal has just
died; its organs from that moment are subject to the action of
chemical affinities only; decomposition takes place, gases are
disengaged, fluids flow out and new solid aggregates are formed.
After a time every molecular motion ceases; there remains only a
certain number of binary, ternary combinations, &c. Here then is
an _assemblage of phenomena taking place for a limited time in an
organized body_, and yet it is not life.
[3] This distinction of the two lives is bad, inasmuch as it tends
to separate phenomena which have a very intimate connexion, which
relate to a common object, and which are often produced by means in
every respect similar. Why should I rank among the organs of animal
life the muscular apparatus which carries the alimentary mass
from the mouth into the oesophagus, and among those of the other
life, that which takes it from the cardiac orifice to the anus? Is
not the action of the first apparatus in relation with nutrition
as well as the action of the last, and does not the muscular
apparatus of the oesophagus act upon a body which is foreign to us,
as well as that of the tongue and the pharynx? Do the motions of
mastication differ in their object from those of which we have just
spoken, and as to the means of execution, does not the muscular
action still perform the principal part?
We might in the same way bring near each other the motions by
means of which we seize our food. The action itself of the senses,
which directs these motions, is, with nutrition, in a relation
more remote, but not less necessary, and we see in the various
classes of animals that their apparatus is modified according to
the different kinds of nourishment. If the distinction of the two
lives be wanting in justice, as to the object of the functions it
separates, we shall soon see that the characters attached to the
organs of one and the other do not establish this division in a
more striking manner.
[4] This division between vegetables and animals is far from being
so striking as is here supposed; these two classes of beings,
so different when we examine them in the individuals endowed
with a very complicated organization, approximate each other
in a remarkable degree, when we descend to those species whose
structure is most simple; it is even remarkable that the most
constant character which distinguishes one from the other, is not
found in the organs of animal life, but in those of vegetable or
organic life. The senses are one after the other found wanting;
for in an individual in whom we can discover no nervous system,
there is no more reason to suppose the existence of the sense of
touch as a sensation, than to suppose it in the sensitive plant,
the dionæa muscipula, and other similar plants; we see only action
and reaction. The motions of the arms of certain polypi no more
suppose volition than the motion of the root which follows a wet
sponge, or that of the branches which turn towards the light;
the only very constant character is the absence or presence of a
digestive cavity. To speak of an animal as a vegetable clothed with
an external apparatus of organs of relation, is a more brilliant
than profound view of the subject. Buisson, who, in his division
of the physiological phenomena, avoids this inaccuracy, has
himself fallen into error; he pretends that respiration belongs
exclusively to animals; and that thus the division of Bichat was
not only unfounded but also incomplete, since this function,
which is neither of vegetation nor of relation, could be ranked
under neither life. Buisson was not well informed; no doubt the
respiration of vegetables does not exhibit the most apparent
phenomena of the respiration of the mammalia, but every thing,
which essentially constitutes the function, is found in the one as
well as in the other; absorption of the atmospheric air, and the
formation and exhalation of a new gas; the rest is only accidental
and is not an appendage but in certain classes of animals. In some
reptiles, though we find a particular organ for respiration, this
organ is not indispensable; it may be removed, and the skin becomes
the only respiratory organ; and when finally we come to consider
animals with _tracheæ_, we see that the conformity becomes more and
more evident.
[5] Bichat seems here to adopt the generally received opinion
that it is the chyle which furnishes to the mammary gland the
materials of which the milk is composed. We know not whence this
opinion arises, if it be not from the gross resemblance which the
chyle and milk often exhibit. This resemblance, if it were very
great, would be a poor reason for admitting, without anatomical
proof, so singular a fact; but it is very far from being perfect.
The chyle in fact does not exhibit the milky appearance and the
white opaque colour, only when the animal from whom it is taken,
has fed upon substances containing fat; in all other cases, it is
almost transparent; its odour and taste, under all circumstances,
differ entirely from those of milk; if these two fluids are left
to themselves, the milk remains a long time without coagulating,
but the chyle almost immediately coagulates, and then separates
into three parts. The solid portion soon exhibits cells, and an
appearance of organization; nothing similar is seen in the coagulum
of milk; the serum of the milk remains colourless when exposed
to the simple contact of the air, that of the chyle assumes a
rosy tint, often very vivid. Finally, if we examine the chemical
composition of these two fluids, we shall find in them differences
still more striking. (See for farther details, my Elements of
Physiology, Vol. 2d.)
CHAPTER II.
GENERAL DIFFERENCES OF THE TWO LIVES WITH REGARD TO THE OUTWARD
FORM OF THEIR RESPECTIVE ORGANS.
The organs of the animal life are symmetrical, those of the organic
life irregular in their conformation; in this circumstance consists
the most essential of their differences. Such character, however,
to some animals, and among the fish, to the sole and turbot
especially, is not applicable; but in man it is exactly traced, as
well as in all the genera which are nearest to him in perfection.
In them alone am I about to examine it.
I. _Symmetry of the external forms of the animal life._[6]
Two globes in every respect the same, receive the impressions of
light. Sounds and odours, have also their double analogous organ.
A single membrane is affected to savours, but the median line is
manifest upon it, and the two segments, which are indicated by it,
are exactly similar. This line indeed is not every where to be seen
in the skin, but it is every where implied. Nature, as it were,
has forgotten to describe it, but from space to space she has laid
down a number of points, which mark its passage. The cleft at the
extremity of the nose, of the chin, and the middle of the lips, the
umbilicus, the seam of the perineum, the projection of the spinous
apophyses of the back, and the hollow at the posterior part of the
neck are the principal points at which it is shewn.
The Nerves, which transmit the impressions received by the senses,
are evidently assembled in symmetrical pairs.
The brain, the organ (on which the impressions of objects are
received) is remarkable also for the regularity of its form. Its
double parts are exactly alike, and even those which are single,
are all of them symmetrically divided by the median line.
The Nerves again, which transmit to the agents of locomotion and of
the voice, the volitions of the brain, the locomotive organs also,
which are formed in a great degree of the muscular system, of the
bony system, and its dependencies, these together with the larynx
and its accessories, composing the double agents of volition, have
all of them a regularity, a symmetry, which are invariable.
Such even is the truth of the character which I am now describing,
that the muscles and the nerves immediately cease to be regular,
as soon as they cease to appertain to the animal life. The heart,
and the muscular fibres of the intestines are proofs of this
assertion in the muscles; in the nerves, the great sympathetic, is
an evidence of its truth.
We may conclude then from simple inspection, that Symmetry is the
essential character of the organs of the animal life of man.
II. _Irregularity of the exterior forms of the organic life._
If at present we pass to the viscera of the organic life, we shall
perceive a character directly the contrary of the former. The
stomach, the intestines, the spleen, the liver, &c. are all of them
irregularly disposed.
In the system of the circulation, the heart and the large vessels,
such as the upper divisions of the aorta, the vena azygos, the vena
portæ, and the arteria innominata have no one trace of symmetry.
In the vessels of the extremities continual varieties are also
observed, and when they occur, it is particularly remarkable that
their existence on one side in no way affects the other side of the
body.
The apparatus of respiration appears indeed at first to be exactly
regular; nevertheless, the bronchi are dissimilar in length,
diameter, and direction; three lobes compose one of the lungs,
two the other: between these organs also, there is a manifest
difference of volume; the two divisions of the pulmonary artery
resemble each other neither in their course, nor in their diameter;
and the mediastinum is sensibly directed to the left. We shall thus
perceive that symmetry is here apparent only, and that the common
law has no exception.
The organs of exhalation and absorption, the serous membranes, the
thoracic duct, the great right lymphatic vessel, and the secondary
absorbents of all the parts have a distribution universally unequal
and irregular.
In the glandular system also we see the crypts, or mucous follicles
disseminated in a disorderly manner in every part; the pancreas,
the liver, the salivary glands themselves, though at first sight
more symmetrical, are not exactly submitted to the median line;
added to this, the kidneys differ from each other in their
situation, in the length and size of their artery and vein, and in
their frequent varieties more especially.[7]
From considerations so numerous we are led to a result exactly the
reverse of the preceding one; namely, that the especial attribute
of the organs of the interior life is irregularity of exterior form.
III. _Consequences resulting from the difference of exterior form
in the organs of the two lives._
It follows from the preceding description, that the animal life is
as it were double; that its phenomena performed as they are at the
same time on the two sides of the body, compose a system in each of
them independent of the opposite system; that there is a life to
the right, a life to the left; that the one may exist, the other
ceasing to do so, and that they are doubtless intended reciprocally
to supply the place of each other.
The latter circumstance we may frequently observe in those morbid
affections so common, where the animal sensibility and mobility
are enfeebled, or annihilated on one side of the body, and capable
of no affection whatever; where the man on one side is little more
than the vegetable, while on the other he preserves his claim to
the animal character. Undoubtedly those partial palsies, in which
the median line, is the limit where the faculties of sensation and
motion finish, and the origin from whence they begin can never be
remarked so invariably in animals, which, like the oyster, have an
irregular exterior.
On the contrary the organic life is a single system, in which
every thing is connected and concatenated; where the functions on
one side cannot be interrupted, and those on the other subsist. A
diseased liver influences the state of the stomach; if the colon on
one side cease to act, that upon the other side cannot continue in
action: the same attack, which arrests the circulation in the right
side of the heart, will annihilate it also in the left side of the
heart. Hence it follows, the internal organs on one side being
supposed to suspend their functions, that those on the other must
remain inactive, and death ensue.
This assertion, however, is a general one; it is only applicable
to the sum of the organic life, and not to its isolated phenomena.
Some of them in fact are double, and their place may be
supplied--the kidneys and lungs are of this description.
I shall not enquire into the cause of this remarkable difference,
which in man, and those animals which approach him the nearest,
distinguishes the organs of the two lives. I shall only observe,
that it enters essentially into the nature of their phenomena, and
that the perfection of the animal functions is so connected with
the general symmetry observed in their respective organs, that
every thing which troubles such symmetry, will more or less impair
the functions.
It is from thence, no doubt, that proceeds this other difference
of the two lives, namely, that nature very rarely varies the usual
conformation of the organs of the animal life. Grimaud has made
this observation, but has not shewn the principle on which it
depends.
It is a fact, which cannot have escaped any one the least
accustomed to dissection, that the spleen, the liver, the stomach,
the kidneys, the salivary glands, and others of the internal life,
are frequently various in form, size, position, and direction.
Such in the vascular system are these varieties, that scarcely
will any two subjects be found exactly alike under the scalpel of
the anatomist: the organs of absorption, the lymphatic glands in
particular, are rarely the same either in number or volume, neither
do the mucous glands in any way affect a fixed and analogous
situation.
And not only is each particular system subject to frequent
aberrations, but the whole of the organs of the internal life are
sometimes found in the inverse of the natural order. Of this I have
lately seen an instance.
Let us now consider the organs of the animal life, the senses, the
brain, the voluntary muscles, and the larynx: here every thing
is exact, precise, and rigourously determined. In these there
is scarcely ever seen a variety of conformation; if there do
exist any, the functions are troubled, disturbed, or destroyed:
they remain unaltered in the organic life, whatever may be the
disposition of the parts.
The difference with respect to action, in the organs of the two
lives, depends, undoubtedly, upon the symmetry of the one, whose
functions the least change of conformation would have disturbed,
and on the irregularity of the other, with which these different
changes very well agree.
The functions of every organ of the animal life are immediately
connected with the resemblance of the organ to its fellow on
the opposite side if double, or if single to its similarity of
conformation in its two halves: from hence the influence of organic
changes upon the derangement of the functions may be well conceived.
But this assertion will become more sensible, when I shall have
pointed out the relations which exist between the symmetry and the
irregularity of the organs, and the harmony and the discordance of
their functions.
FOOTNOTES:
[6] It is rather to the external forms that symmetry appears
to have been primitively attached, and it is in some measure
accidentally and because the nature of their functions requires
in general that they should be placed on the exterior, that the
organs of relation are found modified in virtue of this law. In
the example cited, of fishes without a bladder, the eyes, to lose
nothing of their utility, must be differently placed, and on the
face, which alone is in relation with the light; yet even in this
case, the symmetry of external forms has been displaced rather
than destroyed, and at the first examination it seems complete.
When the organs of relation are found placed on the interior, they
frequently exhibit some irregularity, and to take an example of
a known animal, the organ of voice, in the male duck, is a very
remarkable one; in man even, the wind-pipe is not symmetrical,
after it arrives at the first division of the bronchia. On the
contrary, among the organs of the other life, those which are
prominent on the exterior, constantly present the symmetrical
character, as the thyroid gland; the mammary glands, &c.
[7] If we deny symmetry to the kidneys, because they are not
uniformly composed of the same number of lobes in children, we must
deny it also to the brain, the two lobes of which never exhibit the
same arrangement in their circumvolutions; if we deny it to the
salivary glands, because one is larger than the other, we must deny
it to the extremities, because the right is usually more developed
than the left. If these examples are not enough, a host of others
might be cited; such as, the atrabiliary capsules, the bladder, the
different organs of generation and lactation, and the very regular
arrangement of the mucous follicles in certain parts situated upon
the median line, &c. As to the anomalies that are observed in the
distribution of the blood-vessels, they are also observed very
frequently, though in a less evident manner, in the distribution of
the nervous branches.
CHAPTER III.
GENERAL DIFFERENCE OF THE TWO LIVES WITH REGARD TO THE MODE OF
ACTION OF THEIR RESPECTIVE ORGANS.
Harmony is to the functions of the organs, what symmetry is to
their conformation; it supposes a perfect equality of force and
action, between their similar parts, just as symmetry indicates an
exact analogy of external form, and internal structure: indeed it
is a necessary consequence of symmetry, for two parts essentially
alike in structure, cannot much differ in their manner of action.
Hence we should be naturally led to the following conclusion,
namely, that harmony is the character of the animal, discordance
that of the organic functions. But on these points we must be more
particular.
I. _Of harmony of action in the animal life._
We have already observed, that the animal life arises from the
successive actions of the senses, the nerves, the brain, the
locomotive organs, and the voice. We shall now consider what
harmony of action is, in each of these great divisions.
The precision of our sensations appears to be the more complete
in proportion as there exists a resemblance between the two
impressions, of which they are each of them the assemblage. We see
inaccurately when one of the eyes is better formed, and stronger
than the other; when it conveys to the brain a clearer image than
its fellow does. It is to avoid this confusion that we shut one
eye, while the action of the other is increased by the application
of a lens, for at such time there can be no harmony of action in
the two organs; accordingly, we make use of one of them only in
order to avoid the discordance of the impression.--What a lens
applied to one eye only produces artificially, is exemplified in
a natural way by squinting.--We squint, says Buffon, because we
turn the weaker eye from the object on which the stronger is fixed;
for in so doing we avoid the confusion, which would arise from the
perception of two dissimilar images.
We know that many other causes may contribute to the production
of this effect, but we cannot doubt the reality of the reason
assigned. We know also, that in some animals each eye may act
without the assistance of the other, and that two different objects
may be transmitted at the same time by the two eyes of certain
other animals; but this circumstance, when the action of both the
organs is united upon a single object, should by no means prevent
a similarity in the two impressions. A single sensation is the
consequence of the combination; but in what way can such sensation
be formed with accuracy, if the same body at the same time be
pictured both in strong and weak colours on the one and the other
of the retinæ?
What we have said of the eye may be equally well applied to the
ear. If, of the two sensations which form a sound, the one be
received by a strong and well formed organ, the other by a weak
one, the impressions will be unequal; the brain also, because it
is differently affected by each, will be the seat of an imperfect
perception. Such conformation constitutes what is called an
incorrect or false ear. For what reason does it happen that one
man is unpleasantly affected by a dissonance, while another does
not even perceive it? The reason is this, that in the one, the
two perceptions of the same sound are identical; in the other,
dissimilar.[8] For the same reason a man with a correct ear will
combine his dancing with the cadence of the measure given him;
another without this similarity of organ will be as constantly at
variance in his motions with the orchestra.
Buffon has confined his observations on harmony of action, to the
organs of vision and hearing; we shall push our examination of it
farther.
In the sense of smelling, as well as in the other senses, we must
admit of two impressions; the one primitive, and belonging to the
organ, the other consecutive, and affecting the sensorium: now the
latter may vary, the former remaining unaltered. Many odours are
disagreeable to some, but pleasant to others; and this, not because
there is any difference in the affection of the pituitary membrane,
but because in different individuals, the mind may attach a very
different sentiment to the same impression.--Hence a variety of
results does not in this case suppose a difference of principle.
But sometimes the impression which is made upon the pituitary
membrane does really differ from that which it ought to be, for
producing perfect sensation. Two dogs pursue the same game; the one
never loses scent, but makes the same turnings and windings with
the animal before him; the other follows his game also, but often
stops and hesitates, endeavors to recover the scent, proceeds and
stops again. The first of these receives a lively impression of the
scented emanation; the organs of the second are only confusedly
affected. Now it may be asked whether this confusion does not
arise from the unequal action of the two nostrils, from the
superior organization of the one, and from the imperfection of the
other?--the following observations appear to decide the question.
In the coryza, which affects but one of the nostrils, if the two
be suffered to remain open, the sense of smelling is confused; but
let the diseased nostril be shut, and the smell shall immediately
become distinct. A polypus in one of the nostrils debilitates the
action of the pituitary membrane on the affected side, the other
remaining in its healthy state: hence, as in the preceding case,
ensues a want of harmony in the two organs, and the same confusion
in the perception of odours. The greater number of the affections
of a single nostril have similar effects, which may be all of them
corrected by the same means. And wherefore? because in rendering
one of the pituitary membranes inactive, we put a stop to the
discordance which is occasioned by the deficiency of action in the
other. From the above facts (since any accidental cause, which
destroys the harmony of action in these organs, is capable of
rendering the perception of odours inexact) we may conclude, that
when the perception is naturally inaccurate, there is a natural
dissimilarity in the formation of the organs, and therefore a
difference of power in them.
The same reasoning may be applied to the sense of taste. It is
often the case that one side of the tongue is affected by palsy
or spasm, the median line dividing the insensible half from the
other, which continues to preserve its sensibility. But such
affection may take place in a variety of degrees, and one side of
the tongue retain a power of perceiving savours though in a less
perfection than the other side. In such case it is natural to
suppose that the taste must be confused; because a clear perception
cannot be the consequence of two unequal sensations.
The perfection of the touch as well as that of the other senses,
is essentially connected with uniformity of action in the two
symmetrical halves of the body, and particularly in the hands. Let
us suppose, for instance, a man born blind, to have one hand well
organized, the other defective in the power of moving the thumb
and fingers, and forming only a stiff and immovable surface; such
person would find it a very difficult thing to acquire a just
notion of the size and figure of bodies, because the same sensation
would not arise from the successive application of each hand to the
same substance. Let both of his hands, for example, be supposed to
touch a small sphere; the one by the extremities of the fingers
will embrace it in all its diameters, and convey to him the idea
of roundness; the other, which will be in contact with it only in
a few points, will produce a very different sensation. Embarrassed
between these two bases of his judgment, he will scarcely be able
to decide, nay, it is even possible that he may form a double
judgment from the double sensation which is presented him: his
ideas would be more correct were he to use only the perfect hand,
in the same manner as the person who squints, makes use of the
perfect eye only. Our hands then assist each other reciprocally;
the one confirms the notions which are given us by the other; hence
the necessary uniformity of their conformation.
The hands are not the only instruments of the sense of touch. The
axilla, the groin, the concavity of the foot and many other parts,
may all of them from their application to bodies, afford us so many
bases for our judgments with regard to external form. Now, if one
half of the body were differently arranged from the other half,
the same uncertainty in perception would infallibly be the result.
From all that has been said, we may conclude, that in the external
organs of sense, a harmony of action in the two symmetrical parts,
or the two similar halves of the organ, is a condition essential to
the perfection of sensation.
The external senses are the natural excitants of the brain. The
functions of the brain succeed to theirs, and this organ would
but languish, were it not to find in them the principle of its
activity. From sensation follow perception, memory and imagination;
from these the judgment. Now it is easy to prove, that these
different functions, commonly known by the name of the internal
senses,[9] are governed in their actions by the same laws, which
influence the external senses; and that like them, they approach
the nearer to perfection in proportion to the degree of harmony
existing in the symmetrical parts, in which they have their seat.
Let us suppose for instance one hemisphere of the brain to be
better organised, and therefore susceptible of livelier affections
than its fellow; in such case the perception of the individual
would be confused, for the brain is to the soul what the senses are
to the brain; it transmits to the soul the impressions conveyed to
it by the senses, as the senses convey to the brain the impressions
made upon them by external objects. But, if the defect of harmony
in the external senses confuse the perception of the brain, why may
not the soul perceive but confusedly, when the two hemispheres of
the brain are unequal in power, and incapable of blending into one
the double impression, which is made upon them?
The memory is the faculty of re-producing former sensations,
the imagination that of creating new ones, now in the act of
remembering or imagining, each hemisphere of the brain appears
to re-produce, or to create a sensation of its own. If both do
not act alike, the perception of the mind, which ought to be the
result of the two sensations united, will be inexact and irregular.
But, it is evident, that there will be a disparity in the two
sensations, if there be a disparity in the two halves of the brain,
in which they have arisen, and since the general foundations of
the judgment are made up of the faculties of perception, memory,
and imagination, if these be confused, the judgment itself must be
confused also.
We have now supposed an inequality of action in the hemispheres
of the brain, and inferred, that the functions would in this
supposition be imperfect; but what as yet is only supposition, in
a variety of instances can be proved to be a fact; for nothing is
more common than to find in consequence of compression on either
hemisphere by blood, pus, or exostosis, a variety of alterations in
the intellectual functions.
Even when all appearances of actual compression have vanished,
if in consequence of that which has been experienced, a part of
the brain remain enfeebled, the same alterations of mental power
will be found to be prolonged. If both hemispheres of the brain,
however, be affected equally, the judgment though weaker, will be
more exact.[10] Perhaps it is thus, that we should explain those
observations so frequently repeated, of an accidental stroke upon
one side of the head having restored the intellectual functions,
which had long remained dormant in consequence of a blow received
upon the other side.
I now conceive myself to have proved, that with inequality of
action in the hemispheres, there must be confusion of intellect.
I have also pointed out some states of disease, in which such
confusion is evidently the effect of inequality of action so
occasioned; here we see the effect and its cause; but may we not
from analogy, infer a similar cause where we see a like effect?
when the judgment is habitually incorrect, and all the ideas
wanting in precision, may we not be induced to believe, that there
does exist a defect of harmony in the action of the two hemispheres
of the brain? We see inaccurately if nature have not given to both
eyes an equal power; we perceive and judge inaccurately in like
manner, if the two sides of the brain are naturally dissimilar. The
most correct mind, and the soundest judgment, pre-suppose in the
hemispheres a perfect harmony of action; and what a multiplicity of
shades do we not behold in the operations of the understanding? it
is probable that they all of them correspond to so many varieties
in the proportions of power in the hemispheres. Could we squint
with the brain as we do with the eyes--that is to say, could we
receive impressions on one hemisphere only, and form from thence
our determinations, we might then command at will, a precision in
our intellectual operations; but such a power does not exist.
To the functions of the brain succeed those of locomotion and the
voice. The first of these would appear almost to form an exception
to the general law. In considering the two vertical halves of the
body, we shall perceive that the one is constantly more powerful
than the other with respect to the strength and number of its
movements. The right half is that, which from custom, is most made
use of.
To comprehend the reason of this difference; we must make a
difference between strength and agility; strength depends upon the
perfection of the organization, on the energy of the nutritive
process, on the plenitude of life in the muscular fibre; agility,
on the contrary, is the result of habit and frequent exercise.[11]
At present we shall observe, that this disparity of action in the
locomotive organs, does not consist in the difference of their
actual strength, but in that of the agility, with which these
motions are executed.--All is equal in the size, in the number of
fibres, and nerves both of the one and the other of the superior,
or inferior extremities; the difference of their vascular systems
is scarcely any thing. From hence it follows that the discordance
does not exist in nature, but that it is the effect of our social
habits, which by multiplying our movements on one side of the
body, increase their address without much adding to their power.
Such in fact are the wants of society, as to call forth a certain
number of general movements, which must be performed by all in the
same direction, in order to be understood. It is generally agreed,
that this direction shall be from left to right. The letters,
which form the writing of most nations, are in this way directed;
such circumstance occasions the necessity of our using the right
hand to form them in preference to the left, the former being as
much better adapted to this method, as the latter would be to the
contrary one; of this we may convince ourselves by experiment.
The direction of the letters from left to right, imposes on us the
necessity also of casting our eyes upon them in the same direction.
From this habit acquired in reading, arises that of examining
objects in the same manner.
The necessity of similar movements when men are drawn up in line of
battle, has induced almost all nations to handle their weapons with
their right hands; the harmony too which prevails in the dances of
even the most savage people exacts an accord in the limbs, which
they constantly preserve by making all their principal movements
with the right. We might add to these examples a great variety of
others.
The general movements agreed on by society, which, if every one
were not to execute them in the same direction, would be creative
of much confusion; these movements, I say, by the influence of
habit, oblige us for our own particular movements to use the limbs,
which they have brought into action. Hence, the members of the
right side of the body are perpetually in action either for our own
particular wants, or for those which we feel in conjunction with
others.
Now, as the habitude of acting, continually tends to the perfection
of action, we may perceive the reason, why the right side acquires
a greater facility in the performance of many motions than the
left. This increased facility is not original, but acquired.
So remarkable a difference then, in the two symmetrical halves of
the body, is not by nature meant as an exception to the general
law of harmony of action in the external functions; for those
movements, which are executed by the whole of the body, are the
more precise in proportion to the smallness of the difference
existing in the agility of the muscles of the two sides. How
happens it that certain animals leap from rock to rock with such
admirable precision, where the least deviation from the intended
direction, would plunge them into an abyss? how happens it that
they run with such astonishing address on planes, which are
scarcely equal in breadth to the extremities of their limbs? how
happens it that the walk of the very heaviest of animals is never
attended with those false steps so frequent in the progression of
man? The reason must be, that the difference in their locomotive
organs in both sides of the body is scarcely any thing, and that
in consequence there must be a constant harmony of action in these
organs.
He, whose general movements, or those of the whole of the body are
the most perfect, has the least command in particular over those of
the right side; for, as I shall prove hereafter, the perfection of
a part is never acquired but at the expense of that of the whole.
The child, who should be taught to make an equal use of all his
limbs, would possess a precision in his general movements, which he
would find extremely difficult to acquire for those of the right
hand, such as writing or fencing.
I can easily suppose, that some few natural circumstances may have
exercised upon us an influence in our choice with respect to the
direction of those general motions, which the habits of society
have established. Such may be the slight excess of diameter in the
right subclavian artery, and the sensation of lassitude during
digestion, which is more perceived upon the left side on account
of the situation of the stomach, and may therefore have determined
us to act at such time upon the opposite side in preference. Such
also may be the natural instinct, by which, to express our feelings
we carry the right hand to the heart; but these circumstances
are trifling in comparison with the very great difference of the
movements which from the state of civilization exists between the
symmetrical halves of the body; and from this view of the subject,
we cannot but regard this difference as the effect of social
convention, and by no means the intent of nature.
The voice, together with locomotion, is the last act of the animal
life in the natural order of its functions. Now the greater number
of physiologists, and Haller in particular, have indicated as the
causes of want of harmony in the voice, the dissimilarity of the
two portions of the larynx, the inequality of force in the muscles,
which move the arytenoid cartilages, the same inequality of action
in the nerves, which are distributed to each half of the organ,
and the different reflection of sounds in the nostrils and frontal
sinuses. Without doubt a defective voice must frequently depend
upon a faulty ear; when we hear incorrectly, we sing incorrectly;
but when a correct ear is united with a want of precision in the
voice, the cause is then in the larynx.
The most harmonious voice is that, which the two portions of the
larynx produce in an equal degree; where the vibrations on one side
correspond exactly in number, strength and duration with those upon
the opposite side.[12] In the same manner the most perfect singing
will be produced by two voices exactly similar in tone, compass,
and inflection.
From the numerous considerations which I have offered, the
following general conclusion may be deduced--namely, that one
of the most essential characteristics of the animal life, is a
harmony of action in the two analogous parts, or in the two sides
of the simple organ concurring to the same end. The relation which
exists between this harmony of action, which is the character of
the functions, and symmetry of form, which is the attribute of the
organs of the animal life, will easily be seen.
I wish to observe in finishing this section, that in pointing out
the different derangements, which take place in the animal life,
from the want of harmony in the organs, I have only pretended to
assign a single isolated cause of such derangements; I am well
aware that a thousand other causes besides dissimilarity in the
hemispheres of the brain, may affect the operations of the mind.
II. _Of discordance of action in the organic life._
Along with the phenomena of the animal life, let us now consider
those of the organic life, and we shall find that harmony has
nothing to do with them. Of what detriment would it be to the
general health of the individual, should one of his kidneys be
stronger than the other, and secrete more urine; should one of his
lungs be better unfolded than the other, admit more venous, and
send out more arterial blood; should a less organic force be the
lot of the salivary glands on one side than on the other side of
his body? The simple function, to which both organs concur, would
not be performed less perfectly. Whenever but a slight fulness
supervenes on one side of the liver, spleen, or pancreas, the sound
part makes up for the defect, and the function is little disturbed.
The circulation also remains unaltered among the frequent
variations in the vascular system of each side of the body, whether
such variations exist naturally, or whether they arise from some
artificial obliteration of the larger vessels as in aneurism.
Hence we find those numerous irregularities of structure, those
malconformations, which as I have said may be remarked in the
organic life, and nothing of a morbid nature in consequence
arising. From hence we see that almost continual succession of
modifications, which lessen or increase the circle of the organic
functions. The vital powers, and their exciting causes, are
continually varying, and thus occasion a constant instability in
the functions of the organs, for a thousand causes may at every
moment double or triple the activity of the circulation, and
respiration, increase or diminish the quantity of bile, urine, or
saliva, and suspend or augment the nutrition of the parts. Hunger,
food, sleep, motion, rest, and the passions may all of them impress
upon these functions so great a mobility, as every day to make them
run through a hundred degrees of strength or weakness.
In the animal life on the contrary, every thing is uniform and
constant, the powers of the senses cannot experience these
alternate modifications, or at least, not in so marked a manner.
Indeed they are at all times in a state of relation with the
physical powers, which preside over exterior bodies; now the latter
remaining unaltered, such variations would destroy all relative
connexion, and thus the functions cease.
Besides, if this mobility, which characterises the organic life,
were the attribute of sensation--for the same reason it would be
that of all the operations of the mind. In such case of what would
man consist? The perpetual sport of every thing surrounding him, he
would find his existence at one time little different from that of
inanimate matter, at others superior in perfection and energy to
that even which he now enjoys, allied at one time to the brute, at
another, to spiritual nature.
FOOTNOTES:
[8] This supposition, though no doubt ingenious, is not true. If
the want of accuracy of hearing arose in fact from the inequality
of the power of the two organs, this defect might be remedied by
using but one ear; but experience gives a different result. We
shall not discuss, in relation to the same principle of inequality
of the organs, the explanation of strabismus; but at least, for
every thing that relates to the just appreciation of colours, this
principle is no more applicable than to the just appreciation of
sounds. I know a man who has never been able to distinguish the
_blue of the sky_ from _the green of the sea_, and he succeeds no
better by closing one eye.
[9] We cannot, without confounding all the ideas we have formed of
the senses, give this name to the memory, imagination and judgment;
at the most we might give the name of internal senses to certain
sensations which inform us of the particular state of some internal
organ, in the same way as the external senses make us acquainted
with the properties and state of external bodies.
[10] We cannot conceive how the judgment can be weak or strong,
if we do not understand by it that it is habitually accurate or
inaccurate. His judgment is sound who usually perceives the true
relations between things; and this is independent of the number and
variety of the ideas upon which he has to pronounce. The man to
whose mind there is presented but a small number of relations, has
but little imagination; but if these relations be true, we cannot
say that his judgment is weak.
[11] Bichat, in order to retain for the organs of organic life
the character of irregularity in the forms which he had assigned
to them, has been compelled to avail himself of the inequality
of the size of the congenerous organs. He soon repented having
established an uniform principle; and in this case for example,
he is near being condemned by the very sentence which he has
himself pronounced. The locomotive system, in fact, the symmetry of
which no person before him thought of denying, is destitute of it
according to the principle he has established, since it presents in
its two halves an inequality of size and action. In order to avoid
this consequence, Bichat has maintained that the inequality of size
arose from the inequality of action, and that this was the result,
not of an original disposition, but of our social habits only. To
prove this assertion, he has been compelled to heap sophism on
sophism; he cannot in this case be suspected of a wish to deceive;
he was convinced of the truth of the principle, and we know that
to prove what is believed to be true, the weakest reasons always
seem to be sufficient. But these very errors should be turned to
our advantage, by showing us how dangerous is the tendency of
generalizing upon every thing, since it was capable of misleading
so judicious a mind.
Without stopping to refute in detail all the reasons which he has
advanced to support his opinion, we cannot help saying something
of them; and in the first place, the difference of size uniformly
exists; it is evident that it does not arise from great exercise,
since it is found in the infant at birth, and the nourishing artery
of the right arm is larger than that of the left. If the right
arm be not really stronger than the other, why should we always
use it in preference? If we employ it in writing, should we say
with Bichat, that it is only because it is better situated to
move from left to right, in the order in which the characters of
our writing succeed each other; might it not be said, with more
reason, that our letters go from left to right, because it is the
direction in which the right hand most easily traces them? All this
besides relates merely to the form of our characters, since all the
oriental languages are written from right to left; yet it is always
done with the right hand. Is it still said that the necessity of
union in battle has led to the employment of the right arm to hold
the weapons, as if the Hurons or Algonquins fought in close ranks
like our Grenadiers. If this use of the same arm or the same leg
was only conventional, why among some people, is the left side
never preferred?
[12] The theory of wind instruments is not yet sufficiently well
understood, to enable us to say, what sort of influence would be
exerted upon the sound by the inequality of vibrating plates.
(See the article Voice, in my Elements of Physiology, Vol. 2d.)
CHAPTER IV.
GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO DURATION OF
ACTION.
One of the great distinguishing characters of the phenomena of
the animal life in opposition to those of the organic life, has
just been shewn. That, which I am about to examine, is not of
less importance. The functions of the animal life intermit; the
functions of the organic life are performed with an uninterrupted
continuity.
I. _Of continuity of action in the organic life._
Prolong but little the causes which are capable of suspending
respiration, or the circulation of the blood, and life itself
shall be suspended, nay, even annihilated. All the secretions go
on uninterruptedly; if they intermit at all (and those of the bile
and saliva for instance, when not immediately required for the
purposes of digestion and mastication, may be said to intermit)
such intermissions affect the intensity of the secretion only, and
not the entire exercise of the function. Exhalation and absorption
incessantly succeed each other; the process of nutrition must be
continually carried on; the double movement of assimilation and
decomposition from which it results, can only be terminated with
life itself.
In this concatenation of the organic phenomena, each function
depends immediately upon those which precede it. The centre of them
all, the circulation, is immediately connected with the exercise
of them all, for when this is troubled, they languish, when this
ceases, they cease also. Just in the same manner the movements of a
clock all stop with the pendulum. Nor only is the general action of
the organic life connected with the heart; but there cannot exist a
single function of this nature unconnected with all the others, for
without secretion, there can be no digestion, without exhalation
no absorption, without digestion no nutrition. Hence as a general
character of the organic functions may be indicated continuity of
action, and mutual dependence.
II. _Of intermission of action in the organic life._
In the exercise of the functions of the animal life, there will
be regularly seen an alternation of activity and repose, complete
intermissions, and not remissions only.
Fatigued by long continued action, the senses all alike become
for a time, incapable of receiving any further impression. The
ear loses its sensibility to sound, the eye to light, the tongue
to savours, the pituitary membrane to smells, the touch to the
qualities of bodies about which it is conversant, and all this for
the sole reason that the respective functions of these different
organs, have for a long time been exercised.
In like manner, the brain fatigued by too great an effort in
the exercise of any of its powers, in order to regain its
excitability, must cease to act for a period proportioned to the
duration of its preceding action. The muscles also after having
been strongly contracted, before they can contract anew, must
remain for awhile in a state of relaxation. Hence in locomotion,
and the exertion of the voice, there must be intermissions.
Such then is the character peculiar to the organs of the animal
life. They cease to act because they have acted. They become
fatigued, their exhausted powers must be renewed.
This intermission is sometimes general, sometimes partial. When
a single organ, for a long time has been exercised, the others
remaining inactive, it relaxes and sleeps, the others continuing
to watch.--Hence, without doubt, proceeds the reason, why there is
no immediate dependence among the functions of this order on each
other. The senses being shut up against sensation, the brain may
still subsist in action, may remember, imagine, or reflect. In such
case the power of locomotion and the voice also, may equally well
be exercised, and these in like manner may remain unexercised, and
the activity of the senses be in no-wise impaired.
Thus the animal at will may fatigue any one of the parts of this
life, and on this very account, such parts must all of them possess
a capability of being relaxed, a power of repairing their forces in
an isolated manner. This is the partial sleep of the organs.
III. _Application of the law of intermission of action to the
theory of sleep._
General sleep is the sleep of all the parts. It follows from that
law, which with respect to the functions of the animal life,
enchains intermission with periods of action, from that law, by
which this life is particularly distinguished from the organic life.
Very numerous varieties are remarked in this periodical state, to
which all animals are subject. The most complete sleep is that in
which the outward life is entirely suspended. The least perfect
sleep is that which affects one organ only; it is that of which we
have just been speaking.
Between these two extremes there are many intermediate states. At
times perception, locomotion, and the voice only are suspended;
the imagination, the memory, and the judgment remaining in action.
At other times, to the exercise of the latter faculties are added
those of the locomotive organs and the voice.--Such is the sleep,
in which we dream, for dreams are nothing more than a portion of
the animal life escaped from the torpor, in which the other portion
of it is plunged.
Sometimes but very few of the senses have ceased their
communication with external objects. Such is that species of
somnambulism, in which to the action of the brain, the muscles, and
the larynx, are added the very distinct actions of the ear and the
sense of touch.[13]
Sleep then cannot be considered as a constant and invariable state
with regard to its phenomena.--Scarcely ever do we sleep in the
same manner twice together. A number of causes modify in applying
to a greater or less portion of the animal life the laws of
intermission of action. Its different degrees should be marked by
the different functions, which these intermissions affect.
But the principle of it is every where the same from the simple
relaxation of a muscle to the entire suspension of the whole of the
animal life. Its application, however, to the different external
functions, varies without end.
These ideas on sleep are different, no doubt, from that narrow
system, where its cause exclusively placed in the brain, in the
heart, in the large vessels, or in the stomach, presents an
isolated and frequently an illusory phenomenon, as the base of one
of the great modifications of life.
And what is the reason why light and darkness in the natural order
of things, coincide so regularly with the activity or intermission
of the external functions? The reason is this, that during the day
a thousand means of excitement perpetually surround the animal, a
thousand causes exhaust the powers of his sensitive and locomotive
organs, fatigue them, and prepare them for a state of relaxation,
which at night is favoured by the absence of every kind of
stimulus. Thus, in the actual state of society, where this order
is in part inverted, we assemble about us at evening, a variety
of excitants, which prolong our waking moments, and put off until
towards the first hours of daylight, the intermission of our animal
life, an intermission, which we favour besides by removing from the
place of our repose whatever might produce sensation.
We may for a certain time, by multiplying the causes of excitement
about them, withdraw the organs of the animal life from this law of
intermission, which should naturally cause them to sleep; but at
last they must undergo its influence, and nothing can any longer
suspend it. Exhausted by watching, the soldier slumbers at the
cannon’s side, the slave under the whip, the criminal in the midst
of torture.
We must carefully make a distinction, however, between the
natural sleep, which is the effect of lassitude, and that, which
is the consequence of some affection of the brain, of apoplexy,
or concussion, for instance. In the latter case the senses
watch, receive impressions, and are affected as usual, but these
impressions are not perceived by the diseased sensorium; we cannot
be conscious of them. On the contrary, in ordinary sleep the senses
are affected as much, or even more than the brain.
From what has now been said, it follows, that the organic life,
has a longer duration than the animal life. In fact the sum of the
periods of the intermissions of the latter, is almost equal to that
of the times of its activity. We live internally almost double the
time that we exist externally.
FOOTNOTE:
[13] The action of the brain is far from being preserved in
somnambulism. The thread of ideas, on the contrary, is completely
broken, and this is the most striking character which distinguishes
every kind of sleep from wakefulness. The mind then cannot
reflect upon the sensations which it receives, it abandons itself
successively and without any resistance to all those which are
presented, without examining the connexion which they can have
between them. In ordinary sleep, the senses are almost entirely
blunted, the mind receives no other sensations than those which
have been derived from memory; but they present themselves in a
confused manner, without order and in such a way as often to form
the most strange and incoherent images. In somnambulism the action
of many senses, and that of hearing in particular is preserved; the
judgment of the sleeper can then exercise itself not only upon its
reminiscences, but also upon the impressions which are transmitted
to it from without. The sound of a bell or a drum, being heard
while we are in a dream, will immediately modify it. In this way a
person may gain the attention of a somnambulist, and as the latter
possesses the use of his voice, it will be seen by his answers that
his ideas can be directed at will, and led in this way wherever it
is wished; for the impressions that he receives from without, being
stronger than those which come from memory, he will almost always
obey the first.
CHAPTER V.
GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO HABIT.
Another of the great distinguishing characters of the two lives of
the animal, consists in the independence of the one, and in the
dependence of the other on habit.
I. _Of habit in the animal life._
In the animal life every thing is modified by habit. The functions
of this life, whether enfeebled or exhausted by it, according
to the different periods of their activity, appear to assume a
variety of characters: to estimate the influence of habit, it is
necessary to consider two things in the effect of all sensation,
the sentiment, or immediate feeling, which we have of external
objects, and the judgment which is the result of one or more
comparisons made with respect to them. An air, for instance,
strikes the ear; the first impression made upon the organ is, we
know not why, agreeable or painful. This is sentiment--at present
let us suppose the air to be continued. We may now endeavour to
appreciate the different sounds of which it is composed, and to
distinguish their accords. In this we exercise the judgment. Now,
on these two things, the action of habit is inverse. It enfeebles
our sentiment of things, it improves our judgment of them; the more
we regard an object, the less are we sensible of its agreeable or
painful qualities, the better, at the same time, may we judge of
its attributes.
II. _Habit blunts the sentiment._
Let us dwell a little on the foregoing proposition; we have said
that it is the property of habit to enfeeble our sentiments of
things, to bring us into a state of indifference, the middle
term betwixt pain and pleasure. But before we set about to prove
an assertion so remarkable, it will be well to fix the sense
of it with some precision. Pain and pleasure are absolute and
relative.[14] The instrument which tears us in pieces is a cause of
absolute pain. Sexual connexion is a pleasure of the same nature.
Again, the view of a beautiful country delights us, but here the
enjoyment is relative to the actual state of the mind only; its
charms have long since been indifferent to the inhabitant of the
spot. A bougie when for the first time passed into the urethra is
painful to the patient; eight days afterwards he is no longer
sensible of it. Here we have comparative pain. Whatever destroys
the texture of the organ is always productive of an absolute
sensation; the simple contact of bodies at no time produces any
other than a relative sensation.
Hence it is evident that the domain of absolute pleasure or pain,
is much less extensive than that of these feelings when relative.
The very words agreeable, or painful, imply a comparison made
between the impression received by the senses, and the state of
mind on which it is received. Now it is manifest that we could have
referred only to relative pain and pleasure, as being submitted to
the influence of habit. On these we shall occupy ourselves awhile.
And to shew that they are gradually worn away by habit as we have
said, to the point of indifference, a variety of proofs may be
adduced. Every foreign body in contact for the first time, with a
mucous membrane, is creative of a disagreeable sensation, which
by repetition, is diminished, and at last becomes altogether
imperceptible. Pessaries in the vagina, tents in the rectum, the
canula made use of for tying polypi of the nose, or the uterus,
bougies, in the urethra, in the œsophagus, or trachea, styles and
setons in the lachrymal passages, present us every day with these
phenomena. The impressions of which the cutaneous organ is the
seat, are all of them subjected to the same law. The sudden passage
from cold to heat, or from heat to cold, is always the occasion of
a disagreeable sensation, but such sensation gradually and at last
entirely disappears, if the temperature of the atmosphere be within
a certain range and constant. From hence proceed those various
sensations, which we have from the change of climate, or season.
Similar phenomena in the same way are the result of our successive
perceptions of the dry or humid, the soft, or the hard qualities
of bodies, and in general the same may be said of all our relative
sensations, of what kind soever.
With respect to pleasure, we shall repeat what we have said of
pain. The perfumer and the cook are by no means sensible in their
several professions of those pungent enjoyments of which they
are dispensers. In them the habit of perceiving has blunted the
sentiment. The same is the case with all agreeable sensations
whatever. Delightful views and delicious music are productive of a
pleasure, the vivacity of which is soon lessened; for harmony and
beauty if they for a long time continue to solicit our attention,
are successively the sources of pleasure, of indifference, of
satiety, nay even of disgust and aversion. This remark has been
felt by all; Philosophers and Poets have all of them turned it to
their account.
From whence arises this facility, which our sensations have of
undergoing so many different, so many contrary modifications?
To conceive it, let us first remark that the centre of these
revolutions of pleasure, of pain, and of indifference, is by
no means seated in the organs, which receive or transmit the
sensation, but in the soul. The affections of the eye, of the
tongue, and the ear, are at all times the same from the same
objects, but to these affections at different times, we attach
a variety of sentiments. In the second place we shall observe,
that the action of the mind in each several sentiment of pain or
pleasure, which has been the effect of a sensation, consists in a
comparison between this sensation, and that by which it has been
preceded, a comparison, which is not the result of reflection,
but the involuntary effect of the first impression of the object.
Now, the greater the difference between the actual and the past
impression, the livelier will be the sentiment. The sensations
which affect us the most, are those which we never before have
experienced.
The consequence is, that in proportion as the same sensations
are repeated, the less impression do they make upon us, because
the comparison between the present and the past becomes less
sensible. Pain then and pleasure naturally tend to their own
annihilation. The art of prolonging our enjoyments, consists in
varying their causes. Indeed were I to regard the laws of our
material organization only, I might almost say, that constancy
is but one of the happy dreams of the poet, and that the sex to
which we at present bend, would possess but a very weak hold upon
our attentions were their charms too uniform; I might almost
assert that were every female cast in the same mould, such mould
would be the tomb of love. But here let us forbear to insist upon
the principles of physiology, where they tend to the destruction
of those of morality. The one, and the other are equally solid,
though sometimes at variance. We shall only notice, that at times
the former unhappily are our only guides. It is then, that love
disappears, with the pleasure which it has procured, and leaves
us but disgust. It is then, that recollection too often carries
us aside from our duties in rendering uniform that which we feel
and that which we have felt, for such appears to be the essence of
physical happiness, that past pleasure enfeebles the attraction of
that which we enjoy.
The consequences are clear. Physical pleasure is nothing but
a comparative sentiment; it ceases to exist when uniformity
supervenes between the actual and past impression. By means of this
uniformity habit must bring down pleasure to indifference: Such is
the secret of the very great influence which it exercises over our
enjoyments.
Such also is its mode of action on our pains. Time flies, it
is said, and carries away sorrow; time is the true remedy of
grief; and wherefore? The reason is, that the more sensations it
accumulates upon that which has been painful, the more does it
enfeeble the sentiment of comparison between what we are, and what
we were. At last this sentiment becomes extinct. There are no
eternal sorrows.
III. _Habit improves the judgment._
I have just now proved that the sentiment is enfeebled by the
effect of habit. It is as easy to demonstrate, that habit improves
and enlarges the judgment.
When, for the first time, the eye wanders over an extensive
country, or the ear is struck by a succession of harmonious
proportions; when the taste, or the smell for the first time are
affected by any very compound savour or scent, there arise from
these sensations only confused and inexact ideas. We represent to
ourselves the whole, its parts escape us. But let these sensations
be repeated, and in proportion as they are so, will the judgment
become precise and rigorous, and the knowledge of the object be
perfected.
Let us for instance observe the man, who a stranger to theatrical
amusement of every kind is introduced to the Opera. He will
have but a very imperfect notion of it. The dancing, the music,
the scenery, the actors, the splendor of the whole will be all
confounded within his mind in a sort of delightful chaos. But
let him be present at many representations, and whatever in this
charming whole belongs to the several arts, will assume its
separate place. He will have seized its detail, may form a judgment
of it, and this he will do the more accurately in proportion to his
opportunities of observation.
The above example affords us an abridgment of the picture of the
man, who enjoys for the first time the spectacle of nature. The
child, at its birth, is only capable of general impressions, but
habitude, by gradually blunting these impressions, enables him
to seize the particular attributes of bodies, and teaches him to
see, to hear, to smell, to taste and to touch, by making him in
each sensation descend successively from the confused notion of
the whole to the precise idea of its parts. The animal life needs
education, and this is one of its great characters.
Habit then while it hebetates our sentiments, improves our
judgments of things. An example will render this truth
indisputable. Most persons may recollect that in traversing a
meadow, embellished with a variety of flowers, they have been
sensible of a general fragrance only, the confused assemblage of
all the particular odours which are exhaled from each individual
flower; but in a short time from habit this first sentiment is
weakened, it is soon afterwards altogether effaced. They then may
have distinguished the odour of each particular plant, and formed a
judgment at first impossible.
The two contrary operations thus of habit on our sentiments and
judgments, tend as we see to one common end, the improvement,
namely, of the animal life.
IV. _Of habit in the organic life._
Let us at present compare the above-mentioned phenomena with those
of the organic life, and the latter we shall see as constantly
withdrawn from the influence of habit, as the former are subject to
it.--Habit has never modified the circulation, or respiration, has
never changed the mode of the processes of exhalation, absorption,
or nutrition. A thousand causes would every day endanger our very
existence, were these essential functions under the influence of
habit.
The excretion of the urine and fecal matter may, nevertheless, be
suspended, accelerated, and return according to laws determined by
habit. The action of the stomach with respect to hunger, and its
contact with certain aliments, appears also to be subordinate to
habit; but here let us remark, that these different phenomena hold,
as it were, a middle place between the two lives, are found on the
limits of the one and the other, and participate almost as much
of the animal as the organic life. In fact, they all of them take
place on mucous membranes, a species of organ, which being at all
times in relation with bodies foreign to our nature, is the seat of
an inward tact, in every way analogous to the outward tact of the
skin. The two must be necessarily subject to the same laws.--Can we
be astonished at the influence of habit on both of them?
We cannot, and let us remark also, that the greater part of these
phenomena, which begin as it were, and terminate the organic
life, are connected with motions essentially voluntary, and in
consequence, under the dominion of the animal life.
I shall not here enlarge on the numerous modifications of power,
taste, and desire, which have their source in habit. I refer to the
numerous works which have considered its influence in a different
point of view from that which I have indicated.
FOOTNOTE:
[14] Pleasure and pain are always absolute sensations, but they
may depend upon relative circumstances; that degree of cold, for
example, does not incommode the inhabitant of Spitzbergen, which
would be very painful to a man from a temperate climate. In order
to understand how habit produces these effects, we must recollect
that the repetition of the same sensations on the same part
exhausts at length the sensibility of it. Hence we may conceive
how the contact of a body upon a living surface may cease to be
painful, while any division or solution of continuity of one of
our organs will be always more or less so, because the nerves that
are divided are unaccustomed to this sensation, and still possess
their whole sensibility. The sense of sight furnishes us with a
striking example of sensibility being exhausted by the continuation
of the sensation; if we look for a long time with the same eye upon
a white surface with a red spot in the middle of it, and then look
upon a part that is all white, we shall perceive there a greenish
spot; for the part of the retina which has been a long time in
contact with the red rays, loses the peculiar sensibility that
enables it to transmit this sensation perfectly; and of all the
coloured rays which compose the white rays that now go to it, it
transmits only those to which it is unacquainted; hence results the
sensation of green.
CHAPTER VI.
GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO MENTAL
AFFECTION.
It is necessary to consider, under two relations, those acts, which
little connected with the material organization of animals, are
derived from this principle so little known in its nature, but so
remarkable as to its effects, the centre of all their voluntary
motions, and on the subject of which, there would have been less
dispute, if philosophers, instead of attempting to reach its
essence, had been contented with analyzing its operations. These
actions, which we shall consider more especially in man, with
whom they are the most perfect, are either purely intellectual,
and relative to the understanding only; or they are the immediate
product of the passions. Examined under the first point of view,
they are the exclusive attribute of the animal, under the second of
the organic life.
I. _Whatever relates to the understanding belongs to the animal
life._
It would be useless for me to insist on proving that meditation,
reflection, the judgment, and all the operations of the mind
depending upon an association of ideas are under the dominion of
the animal life. We judge from impressions formerly or actually
received, or from those which we ourselves create. Perception,
memory, and the imagination are the principal bases, on which are
founded the operations of the mind, but these very bases themselves
repose upon the action of the senses.
Let us suppose a man at his birth to be deprived of all that
exterior apparatus, which is destined to establish his connexions
with surrounding objects; such man will not altogether be the
statue of Condillac, because, as we shall see hereafter, other
causes besides the sensations, may occasion within him the motions
of the animal life; but at least will he not be able, a stranger
as he is to every thing surrounding him, to form any judgment with
respect to things. The intellectual functions with him will be
null; volition, which is the consequence of these functions, will
not have place, and consequently, that very extensive class of
motions which has its immediate seat in the brain, and which itself
is but an effect of the impressions made there, will in nowise
belong to him.
It is by means of the animal life that man is so great, so superior
to the beings, which surround him; by means of this that he
possesses the sciences, the arts, and every thing which places him
at a distance from the gross elements under which we represent
brute matter; by this that he approaches spirituality; for industry
and commerce, and whatever enlarges the narrow circle within which
the efforts of other animals are confined, are exclusively under
the dominion of the animal life of man.
The actual state of society then is nothing but a more regular
development, a more marked perfection of the exercise of the
different functions of this life; for one of its greatest
characters as I shall hereafter prove, consists in its capability
of being unfolded, while, in the organic life, there does not exist
a part, which in the least degree may pass the limits which are set
to it by nature. We live organically in as perfect, in as regular a
way, when infants, as when men; but what is the animal life of the
child compared with that of the man of thirty years of age?
We may conclude that the brain, the central organ of the animal
life, is the centre of whatever relates to the understanding. I
might here proceed to speak of its volume in man, and in animals,
whose intelligence appears to decrease in proportion as the facial
angle is diminished, and expatiate upon the different alterations
of which the cerebral cavity is the seat, as well as on the
disorders of the intellectual functions arising thence. But these
things are all of them well enough understood. Let us pass to that
order of phenomena, which though as foreign as the preceding to the
ideas which we form of material appearances, are elsewhere seated.
II. _Whatever relates to the passions belongs to the organic life._
My present object is not to consider the passions metaphysically.
It little matters, whether they be all of them the modifications
of a single passion, or dependent each of them upon a separate
principle. We shall only remark, that many physicians in discussing
their influence on the organic phenomena, have not sufficiently
distinguished them from the sensations; the latter are the occasion
of the passions, but differ from them widely.
It is true that anger, joy, and sorrow, would not affect us,
were we not to find their causes in our connexions with external
objects. It is true also, that the senses are the agents of these
relations, that they communicate the causes of the passions, but in
this they act as simple conductors only, and have nothing in common
with the affections, which they produce; for sensation of every
kind has its centre in the brain, sensation of every kind supposing
impression and perception. If the action of the brain be suspended,
sensation ceases; on the contrary, the brain is never affected by
the passions; their seat is in the organs of the internal life.[15]
It is undoubtedly surprising that the passions, essentially as they
enter into our relations with the beings which are placed about
us, that modifying as they do at every moment these relations,
that animating, enlarging, and exalting the phenomena of the
animal life, which without them would be nothing but a cold series
of intellectual movements; it is astonishing, I say, that the
passions should neither have their end, nor beginning in the organs
of this life, but on the contrary, that the parts which serve for
the internal functions, should be constantly affected by them, and
even occasion them according to the state in which they are found.
Such notwithstanding is the result of the strictest observation.
I shall first observe, that the effect of every kind of passion
is at all times to produce some change in the organic life. Anger
accelerates the circulation of the blood, it multiplies the efforts
of the heart. The passion of joy has not indeed so marked an
influence upon the circulation, but alters it notwithstanding, and
carries it lightly towards the skin. Terror acts inversely; this
passion being characterized by a feebleness in the vascular system,
a feebleness, which in hindering the blood from arriving at the
capillary vessels, occasions the paleness which at such time is so
particularly remarked. The effects of sadness and sorrow are nearly
analogous.
So great indeed is the effect which the passions occasion upon the
organs of the circulation, as even to arrest them altogether in
their functions, where the affection is very powerful. In this way
is syncope produced, for the primitive seat of syncope is always,
as I shall soon prove it to be, in the heart, and not in the brain.
In this the latter organ ceases to act, only because it ceases to
receive the excitant necessary to its action. Hence also may happen
death itself, the sometimes sudden effect of extreme emotion,
whether such emotion as in anger so far exalts and exhausts the
powers of the circulation, as not to leave them any further
excitability, or whether as in the death occasioned by excessive
grief, the powers at once excessively debilitated, are no longer
capable of returning to their usual condition.
If the total and instantaneous cessation of the circulation be not
occasioned by this debility, a variety of lesions in the blood
vessels may be, notwithstanding, the effect of it. Desault has
remarked that diseases of the heart, and aneurisms of the aorta,
were augmented in number during the revolution, in proportion to
the evils which it produced.
Nor does respiration depend less immediately upon the passions;
that oppression, that anxiety, and sense of suffocation, which is
the sudden effect of profound sorrow, must imply in the lungs a
remarkable change and sudden alteration. In that very long series
of chronic or acute affections, the sad attribute of the pulmonary
system, must we not often look to the passions to find the
principle of the disease?
And that lively sensation at the pylorus under strong emotion,
that ineffaceable impression which sometimes remains there, from
whence succeed the schirri of which it is the seat, that sentiment
of stricture, as it were, about the stomach, about the cordia in
particular; under other circumstances those spasmodic vomitings,
which sometimes follow the loss of a beloved object, the news of
a fatal accident, or any kind of trouble, the cause of which are
the passions; that sudden interruption of the digestive phenomena
either in consequence of agreeable or disagreeable news, those
affections of the bowels, those organic lesions of the intestines,
of the spleen observed in cases of melancholy, or hypochondria,
diseases which are always preceded by sad forebodings and the
darker affections of the mind; do not all these indicate the very
strict connexion of the digestive viscera with the state of the
passions?
They do; and the secreting organs have not a less connexion with
them. Sudden fear suspends the course of the bile, and is the
occasion of jaundice; sudden anger is often the origin of bilious
fever. In a state of sorrow or joy, sometimes even in that of
admiration, our tears flow abundantly: the pancreas is not less
frequently affected in hypochondria.
But the functions of the circulation, of digestion, respiration and
secretion, are those which are most directly under the influence
of the passions; those of exhalation, absorption and nutrition
appear to be less so. Doubtless, the reason of this is, that these
functions have not as the former any principal focus, or essential
viscera, the state of which may be compared with that of the mind.
Their phenomena disseminated throughout all the organs belong
exclusively to none, and cannot be observed as well as those, the
effects of which are confined within a narrow compass.
Nevertheless, the alterations, which these functions experience are
not less real, do not become less apparent after a certain time;
let the man, whose hours are marked by sorrow, be compared with
him, who lives in peace of mind, and the difference of the process
of nutrition in the one and in the other will easily be seen.
Let us, for a moment, approximate the times, when the terrible
passions of sorrow, of fear and revenge seemed to brood over our
country, and those, when safety and abundance continually supplied
us with the gayer ones so natural to us; we may then recall what
at the two periods were the outward appearances of our countrymen,
and appreciate the influence of the passions on the process of
nutrition. The very expressions which are continually in our mouths
that such a one is dried up with envy, preyed upon by remorse,
consumed and wasted away with sorrow, do not even these announce
how much the nutritive functions are modified by the passions?
I know not for what reason the powers of absorption and exhalation
should not be subject to the same influence, though they appear to
be less so; may not dropsies, and all infiltrations of the cellular
membrane, the peculiar vices of these two functions, depend on
mental affection?
In the midst of these disturbances, of these partial or general
revolutions which are produced by the passions in the organic
phenomena, let us consider the actions of the animal life;
they constantly remain unaltered, or if they do experience any
derangement, such derangement has ever its source in the internal
functions.
From so many considerations we may conclude that it is upon the
organic and not upon the animal life that the passions exercise
their influence. Accordingly, whatever serves to paint them must
relate to the former. Of this assertion, our gestures which are
the mute expressions both of the sentiment and understanding are a
remarkable proof. Thus if we indicate any operation of the memory,
imagination or judgment, the hand is carried to the head; do we
wish to express either love or hatred, or joy or sorrow, it is to
the seat of the heart, the stomach or intestines, that it is then
directed.
The actor, who should mistake in this respect, who in speaking of
sorrow should refer his gestures to his head, or carry them to his
heart, for the purpose of announcing an effort of genius, would be
ridiculed for a reason which we should better feel than comprehend.
The very language of the vulgar, at a time when the learned
referred to the brain, as the seat of the soul, affections of all
kinds, distinguished the respective attributes of the two lives.
We have always said a strong head, a head well organized to denote
perfection of mind; a good heart, a sensible heart, to indicate
proper feeling. The expressions of fury circulating in the veins,
and stirring up the bile; of joy making the heart leap, of
jealousy distilling its passions into the heart, are by no means
poetical expressions, but the enunciation of that which actually
takes place in nature. In this way do all these expressions, the
language of the internal functions enter into our poetry, which in
consequence is the language of the passions or the organic life, as
ordinary speech, is that of the understanding or the animal life.
Declamation holds a middle place between the two, and animates the
cold language of the brain by the expressive language of the inward
organs.
I shall even venture to assert that anger and love inoculate,
if I may so express myself, into the humours, into the saliva
particularly, a radical vice, which renders dangerous the bite of
animals at such times; for these passions do really distil into the
fluids a poison, as we indicate the fact by our common expressions.
The violent passions of the nurse have frequently given her milk a
pernicious quality, from whence disease has followed to the child;
and in the same way shall we explain from the modifications which
the blood of the mother receives under strong emotion, the manner,
in which these emotions operate on the nutrition, the conformation,
and even on the life of the fœtus. And not only do the passions
essentially influence the organic functions, in affecting their
respective viscera, but the state of these viscera, their lesions,
the variation of their forces concur in a decided way to the
production of the passions themselves. Their relations with age and
temperament, establish incontestably this fact.
Who does not know for instance, that the individual of the sanguine
temperament, whose expansion of lungs is great, whose circulatory
system is large and strong; who does not know that such a man
is possessed of a disposition to anger and violence? that when
the bilious system prevails, the passions of envy and hatred are
more particularly developed? that when the lymphatic system is
pronounced, are pronounced also the inactivity and dulness of the
individual?
In general that which characterises any particular temperament,
consists in a correspondent modification on one hand of the
passions, and on the other of the state of the organic viscera. The
animal life is almost always a stranger to the attributes of the
temperaments.
The same may be said of age; the weakness of the organization of
the child coincides with his timidity. The development of the
pulmonary and vascular system, with the courage and temerity of the
youth; that of the liver, and the gastric system with the envy,
ambition and intrigue of manhood.
In considering the passions as affected by climate and season, the
same relations are observed between them and the organic functions;
but physicians have sufficiently noticed these analogies, and it
would be useless to repeat them.
At present, if from man in a state of health, we look to man in
a state of disease, we shall see that the lesions of the liver,
of the stomach, of the spleen, the intestines and heart produce a
variety of alterations in our affections, which all of them cease
together with their causes.
The ancients, better than our modern mechanicians, then were
acquainted with the laws of the economy, in supposing that our bad
affections were evacuated by purgatives, together with the noxious
humours of the body. By disembarrassing the primæ viæ they got rid
of these affections. In fact how dark a tint does the fulness of
the gastric viscera cast upon the countenance! the errors of the
first physicians on the subject of the atrabilis, were a proof
of the precision of their observations on the connexion of these
organs with the state of the mind.
In this way every thing tends to prove, that the organic life, is
the term, in which the passions end, and the centre from whence
they originate. But we shall be asked perhaps, why vegetables,
which live organically, do not offer any vestige of them? the
reason seems to be, that besides their want of the natural
excitants of the passions, namely the external apparatus of the
senses, they are wanting also in those internal organs, which
concur most especially to their production, such as the digestive
system, that of the general circulation, and that of the great
secretions, which are remarked in animals.
Such are the reasons also why the passions are so obscure in the
Zoophytes, in worms, &c. and why in proportion as the organic
life becomes more simple in the series of animals, and loses its
important viscera, the passions are less observable.
III. _The passions modify the actions of the animal life though
seated in the organic life._
Although the passions are the especial attributes of the organic
life, they nevertheless exert an influence over the animal life,
which it is necessary to examine. The muscles of volition are
frequently brought into play, and their actions sometimes exalted,
sometimes lowered by them; the strength for instance of the man
in anger is doubled, and tripled; is exercised with an energy, of
which he is not himself the master. The source of this augmented
power is manifestly in the heart.
This organ, as I shall prove hereafter, is the natural excitant
of the brain, by means of the blood, which it sends thither. The
energy of the cerebral action is in proportion to the energy of
the stimulus applied to it, and we have seen that the effect of
anger is to impress a great vivacity upon the circulation; hence,
a larger quantity of blood than usual is thrown upon the brain in
a given time. The consequence is an effect analogous to that which
happens in the paroxysm of ardent fever, or the immoderate use of
wine.
It is then, that the brain being excited strongly, excites as
strongly the muscles which are submitted to its influence;
accordingly their motions must be involuntary, for the will is a
stranger to those spasms, which are determined by a cause which
irritates the medullary organ. Such cause may be a splinter of
bone, blood, pus, the handle of a scalpel as in our experiments; in
short of various kinds.
The analogy is exact, the blood being transmitted to the brain in
greater quantity than usual, produces upon it the effect of the
different excitants above mentioned. In these different motions
then, the brain is passive; it engenders indeed at all times the
necessary irradiations for producing such motions, but these
irradiations in the present instance are not the effect of the will.
It may be observed also, that under the influence of anger, a
constant relation exists between the contractions of the heart and
the locomotive organs; they both increase at the same time, and at
the same time resume their equilibrium. In every other case on the
contrary there is no appearance of this relation; the action of the
heart is uniformly the same, whatever the affection of the muscular
system. In convulsion and palsy, the circulation is neither impeded
nor accelerated.
In the passion of anger, in fact, we see the very mode of the
influence, which the organic life exercises over the animal life.
In the passion of fear also, where on the one hand the enfeebled
heart directs a less quantity of blood, and consequently a smaller
cause of excitement to the brain, and where on the other hand a
debility may be observed in the external muscles, we may perceive
the connexion of cause and effect. This passion offers in the first
degree the phenomenon, which in the last degree is shewn by those
lively emotions, which suspending altogether the efforts of the
heart, occasion a sudden cessation of the animal life and syncope.
But in what way shall we account for those modifications of the
motions of the animal life, which are the effect of the passions?
In what way shall we explain the cause of those infinite varieties,
which succeed each other in the moveable picture of the face?
All the muscles which are the agents of these motions receive their
nerves from the brain and lie under the influence of the will. What
is the reason then, that when acted on by the passions, they cease
to do so, and enter under the class of those motions of the organic
life, which are put forth without our direction or consciousness.
The following if I mistake not is the best explanation of the fact.
The most numerous sympathies exist between the internal viscera,
and the brain or its different parts. Every step which we make
in practice presents us with affections of the brain originating
sympathetically from those of the liver, stomach and intestines.
Now as the effect of every kind of passion is to produce a change
of power in one or the other of these viscera, such change will
sympathetically excite either the whole of the brain or some of its
parts, whose re-action upon the muscles, which receive from thence
their nerves, will produce the motions, which are then observed.
In the production of these motions the cerebral organ accordingly
must be passive, it is active only when the will presides over its
efforts.
The effects indeed of the passions are similar to those diseases
of the internal organs, which by sympathy are the causes of atony,
palsy, and spasm.
But perhaps the inward organs act upon the voluntary muscles, not
by means of the immediate excitement of the brain, but by direct
nervous communication. Of what importance to us is the manner? We
are not at present occupied on the so much agitated question of the
manner of sympathetic communication.
The essential thing is the fact itself. Now in this fact, there
are two things evident; the affection of an internal organ by the
passions, and secondly a motion produced in consequence of such
affection in muscles, on which this organ in the common series of
the phenomena of the two lives has no kind of influence. This is
surely a sympathy, for between it, and those with which convulsion,
or spasm of the face present us, when occasioned by any lesion of
the phrenic centre, or the stomach, the difference is only in the
cause, which affects the internal organ.
Any irritation of the uvula, or the pharynx convulsively agitates
the diaphragm. The too frequently repeated use of fermented liquors
occasions a general trembling of the body. But that which happens
in one mode of gastric affection, may happen in another. What
matters it, whether the stomach or liver be irritated by passion or
by some material cause? It is from the affection, and not from the
cause of the affection that results the sympathy.
Such in general is the manner in which the passions withdraw
from the empire of the will, those motions which by nature are
voluntary. Such is the manner in which they appropriate to
themselves, if I may so express myself, the phenomena of the animal
life, though they possess their seat essentially in the organic
life.
When very strong, the very lively affection of the internal organs
produces so impetuously the sympathetic motions of the muscles,
that the action of the brain is absolutely null upon them; but the
first impression past, the ordinary mode of locomotion returns.
A man is informed by letter and in presence of company, of a piece
of news, which it is his interest to conceal. All on a sudden
his brows become contracted, he grows pale, and his features are
moulded according to the nature of the passion, which has been
excited. These are sympathetic phenomena produced by the abdominal
viscera which have been affected by the passions, and which in
consequence belong to the organic life. But in a short time the man
is capable of putting a constraint upon himself, his countenance
clears up, his colour returns. Meanwhile the interior sentiment
continues to subsist however, but the voluntary have overpowered
the sympathetic motions, the action of the brain has surmounted
that of the stomach or the liver; the animal life of the man has
resumed its empire.
In almost all the passions the movements of the animal life are
mingled with those of the organic life, or succeed to them; in
almost all the passions, the muscular action is in part directed
by the brain, in part by the organic viscera. The two centres
alternately overpowered the one by the other, or remaining in a
state of equilibrium, constitute by the modifications of their
influence, those numerous varieties which are seen in our mental
affections.
And not only on the brain, but on all the other parts of the
body also do the viscera affected by the passions exercise their
sympathetic influence. Fear affects the stomach in the first
place, as is proved by the sense of stricture felt there at such
time.[16] But when thus affected, the organ re-acts upon the skin,
with which it has so strict a connexion, and the skin immediately
becomes the seat of the cold and sudden sweat, which is then so
often felt. This sweat is still however of the same nature with
that which is occasioned by tea, or warm liquids. Thus a glass of
cold water, or a current of cold air, will suppress this excretion
by means of the relation, which exists between the skin, and the
mucous surfaces of the stomach or bronchiæ. We must carefully
distinguish between sympathetic sweating, and that, of which the
cause is directly made upon the skin.
Hence though the brain be not the only term of the re-action of
the internal viscera which are affected by the passions, it is
nevertheless the principal one, and in this respect may always be
considered as a focus at all times in opposition to that which is
centered in the internal organs.
IV. _Of the epigastric centre.--It does not exist in the sense,
which Authors have pretended._
Authors have never been at variance with respect to the cerebral
focus. The voluntary motions have ever been regarded as an
effect of its irradiations. They do not equally agree upon the
subject of the epigastric focus; some of them place it in the
diaphragm, others in the pylorus, others in the plexus of the great
sympathetic nerve.[17]
But on this point, they appear to me to be all of them in the
wrong. They assimilate or rather identify the second with the first
focus--they think, that the passions, as well as the sensations
have their seat in an invariable centre. That, which has led them
to this opinion has been the sentiment of oppression, which is felt
at the cardia under all painful affection.
But it is to be remarked, that in the internal organs, the
sentiment produced by the affection of a part is always an
unfaithful index of the seat and extent of such affection. For
example, hunger must undoubtedly affect the whole of the stomach,
but the sensation of hunger is transmitted to us only by the
cardia. A large inflamed surface in the pleura for the most part
gives rise to a pain, which is felt only in a point. How often does
it happen that in the head or the abdomen a pain which is referred
but to a very limited space coincides with a largely disseminated
affection, with an affection possessing even a different seat
from that which is presumed. We should never consider the place
to which we refer the sentiment as a sure index of that which the
affection occupies, but only as a sign that it exists either there
or thereabouts.
From all this it follows, that to form a judgment of the organ,
to which such or such a passion relates, we ought to recur to the
effect produced in the functions of the organ by the influence of
the passion, and not to the feelings of the patient. In setting out
from this principle it will be easy to see, that it is sometimes
the stomach and alimentary canal, sometimes the sanguiferous
system, sometimes the viscera belonging to the secretions which
experience a change.
I shall not repeat the proofs of this assertion, but supposing it
to be demonstrated, I shall assert that there does not exist for
the passions as there does for the sensations a fixed and constant
centre; that on the contrary the liver, the lungs, the spleen, the
stomach, and the heart, are turn by turn affected, and at such time
form that epigastric centre so celebrated in modern works; and if
in general we refer to this region the sensible impression of all
our affections, the reason is that all the important viscera of
the organic life, are there concentrated. In fact, if nature had
separated these viscera, had the liver for instance been placed
in the pelvis, and the stomach in the neck, the heart and spleen
remaining as they now are seated, in such case the epigastric focus
would disappear, and the local sentiment of our passions vary
according to the part affected.
In determining the facial angle, Camper has thrown much light upon
the proportion of intelligence enjoyed by the several classes of
animals. It appears that not only the functions of the brain, but
that all those of the animal life which are centred there, have
this angle for the measure of their perfection.
It would be a very pleasing thing could we indicate in the same
way a measure, which assumed from the organs of the internal life,
might fix the rank of each species with regard to the passions. The
dog is much more susceptible than other animals of the sentiments
of gratitude, of joy, of sorrow, of hatred, and of friendship;
has he any thing more perfect in his organic life? the monkey
astonishes us by his industry, his disposition to imitate, and
by his intelligence; his animal life is certainly superior to
that of every other species. Other animals, such as the elephant,
interest us by their attachment, their affection, their passions;
they delight us also with their address, and the extent of their
intelligence. With them the cerebral centre and the organic viscera
are perfect alike.
A rapid glance over the series of animals will show us also,
that in some of them the phenomena, which arise from sensation
predominate over those which have their origin in the passions;
in others we shall see the latter superior in power to the
former, and in others again, a balance established between the
two. These circumstances, which we remark in the long chain of
animated beings, we may remark in the human species when considered
individually. In one man the passions are the great principle of
motion; the influence of his animal life is continually surpassed
by that of his organic life, and incessantly induces him to act
in a way to which the will is almost a stranger, and which often
entails upon him the bitterest regret, when his animal life resumes
its empire. In another man, the animal life is the stronger of the
two. In such case, the understanding seems to be augmented at the
expense of the passions, the latter remaining in that silence, to
which the organization of the individual has condemned them.
That man enjoys the happiest constitution in whom the two lives
are balanced, in whom the cerebral and epigastric centres exercise
the one upon the other an equal action, whose intellect is warmed,
exalted, and animated by the passions, but whose judgment makes him
at all times master of their influence.
It is this influence of the passions over the actions of the animal
life, which composes what is named the character. Character as well
as Temperament depends upon the organic life; possesses all its
attributes, and is a stranger to the will in all its emanations;
for our exterior actions form a picture of which the ground and
design do indeed belong to the animal life, but upon which the
organic life extends the shading and colouring of the passions.
The character of the individual is constituted by such shades and
colours.
The alternate predominance of the two lives has been remarked
by almost all philosophers. Plato, Marcus Aurelius, Bacon, St.
Augustine, St. Paul, Leibnitz, Van Helmont, Buffon and many others,
have recognized in man two principles, by one of which we become
the masters of all our moral actions, by the other the contrary.
We have nothing to do with the nature of these principles. Our
business is with their phenomena; we shall analyze the relations by
which they are united.
FOOTNOTES:
[15] Bichat, in this paragraph, seems to say that the perceptions,
which produce in us the passions, go directly and without the
intervention of the brain, from the senses to the organs which he
supposes to be affected by them. We cannot believe that such was
his idea. The paragraph which follows must aid us in understanding
it, and we shall endeavour to elucidate it by means of an example.
A certain event happens; a man is informed of it by means of his
senses; he examines the event in itself, and its relations with
antecedent and future events; his judgment weighs the various
consequences of it, and shows them to be very disadvantageous to
him. Here, as Bichat calls it, is a cold series of intellectual
phenomena, which would take place in the individual, whoever the
man may be who is affected by the event to which he has given his
attention. It is found that the man who is injured is himself;
then, from a knowledge of this only, his heart is sympathetically
affected; its motions become more rapid and stronger, they send
to the brain a greater quantity of blood, and this increase of
habitual excitement in the organ of thought, produces a kind of
mental attention in relation to the event that has taken place.
Thus, without the part that the heart has taken in it, this man
would have seen with the most perfect indifference an event most
disastrous to himself; for without even supposing anger, the least
sentiment of sadness being a passion, we cannot believe that he
is affected with it, if his liver, stomach or spleen are not at
the moment in a particular state. But does not every thing on the
contrary lead us to believe that anger exists before the agitation
of the heart, and that this is the effect of it and not the cause?
This agitation of the heart without doubt, by sending to the brain
a greater quantity of blood than usual, contributes in its turn to
develop and support the kind of alienation which accompanies anger;
but it is necessary that the passion should already exist, since a
favourable event, by producing as rapid motions of the heart, will
produce nothing similar.
[16] There is no proof that the sense of stricture which is felt
in the epigastric region, is connected with the stomach; and if it
were proved that it was so, it would not follow from it that this
organ was primarily affected from fear. The same passion sometimes
acts differently in different individuals; there are some who do
not feel this stricture in the epigastric region, but who are
deprived of the use of their legs; must it be said that in these
individuals the seat of fear is in the extensor muscles of the
legs? If the introduction of a warm drink into the stomach produces
an increase of cutaneous exhalation, should we conclude from
analogy, that it is by acting primarily upon this organ that fear
causes that cold sweat which sometimes accompanies it?
[17] _Note by the Author._--This nervous network, going principally
from the semi-lunar ganglion, belongs to almost the whole
abdominal vascular system, whose various ramifications it follows.
It is, according to the usual manner of considering it, one of
the divisions of the great sympathetic; but it seems to me that
the ideas of anatomists respecting this important nerve are not
conformable to nature.
Every one considers it as a medullary cord, extending from the head
to the sacrum, sending in its course various ramifications to the
neck, the thorax and the abdomen, following in its distributions
a course analogous to those nerves of the spine, and deriving its
origin from those nerves, according to some, and from those of the
brain, according to others. Whatever be the name by which it is
designated, sympathetic, intercostal, &c.; the manner of describing
it is always the same.
I believe that this manner is altogether wrong, that there really
exists no nerve analogous to the one designated by these words, and
that what is taken for a nerve is only a series of communications
between different nervous centres, placed at different distances
from each other.
These nervous centres are the ganglions, scattered throughout the
different regions, they have all an independent and insulated
action. Each is a particular centre which sends in various
directions many ramifications, which carry to their respective
organs the irradiations of the centre from which they go off. Among
these ramifications, some go from one ganglion to another; and as
these branches which unite the ganglions form by their union a kind
of continuous cord, this has been considered as a distinct nerve;
but these branches are only communications, simple anastomoses, and
not a nerve analogous to the others.
This is so true, that these communications are often interrupted.
There are subjects, for example, in whom is found a very distinct
interval between the pectoral and lumbar portions of what is called
the great sympathetic, which seems to be cut off in this place.
I have seen this pretended nerve cease and afterwards reappear,
either in the lumbar or sacral region. Who does not know that
sometimes a single branch, sometimes many go from one ganglion to
another, especially between the last cervical and the first dorsal;
that the size of these branches varies remarkably; and that after
having furnished many divisions, the sympathetic is larger than
before it gave off any?
These considerations evidently prove that the communicating
branches of the ganglions no more suppose a continuous nerve than
the branches which go from each of the cervical, lumbar or sacral
pair to the two pair which are superior and inferior to them. In
fact, notwithstanding these communications, we consider each pair
in a separate manner, and do not regard their union as a nerve.
It is necessary to describe in the same way separately each
ganglion, and the branches which go off from it.
Hence I shall divide hereafter in my descriptions, in which I
have hitherto pursued the ordinary course, the nerves into two
great systems, one arising from the brain, and the other from the
ganglions; the first has a single centre, the second has a great
number of them.
I shall first examine the divisions of the cerebral system; I
shall afterwards treat of the system of the ganglions, which may
be subdivided into those of the head, the neck, the thorax, the
abdomen and the pelvis.
In the head is found the lenticular ganglion, that of Meckel, that
of the sublingual gland, &c. &c. Though no communication connects
these different centres, either together or with the pretended
great sympathetic, yet their description belongs to that of the
nerves of which this is the connecting link, as the communications
are arrangements merely accidental to this system of nerves.
In the neck there are the three cervical ganglions, sometimes
another upon the side of the trachea, in the thorax the twelve
thoracic, in the abdomen the semi-lunar, the lumbar, &c. and in
the pelvis the sacral; these are the different centres whose
ramifications it is necessary to examine separately, as we do those
of the cerebral centre.
For example, I shall first describe the semi-lunar ganglion, as we
do the brain; then I shall examine the branches, among which, is
that by which it communicates with the thoracic ganglions, that is
to say, the great splanchnic; for it is very incorrect to consider
this nerve as giving origin to the ganglion. In the same way, in
the neck and the head, each ganglion will be first described;
then I shall treat of its branches, among which are those of
communications. The arrangement being nearly the same for the
ganglions of the thorax, the pelvis and the loins, the description
of each region will be similar.
This manner of describing the nerves, by placing an evident line
of demarcation between the two systems, exhibits these two systems
such as they really are in nature.
What anatomist, in fact, has not been struck with the differences
that exist between the nerves of these two systems? Those of the
brain are larger, less numerous, whiter, more compact in their
texture and exhibit less variety. On the contrary, the extreme
tenuity, great number, especially towards the plexuses, greyish
colour, remarkable softness of texture and varieties extremely
common are characters of the nerves coming from the ganglions, if
we except those of communication with the cerebral nerves and some
of those which unite together these small nervous centres.
Besides, this division of the general system of the nerves into
two secondary ones, accords very well with that of life. We know
in fact that the external functions, the sensations, locomotion
and the voice are all dependent on the cerebral nervous system;
that on the contrary, most of the organs which perform the internal
functions derive from the ganglions their nerves, and with them
the principle of their action. We know that animal sensibility and
contractility arise from the first, and that where the second alone
are found, there is only organic sensibility and contractility.
I have said that the termination of this kind of sensibility and
the origin of the corresponding contractility are in the organ in
which they are noticed; but perhaps both the termination and origin
are more remote, and are in the ganglion from which the organ
receives its nerves, as the termination of animal sensibility and
the origin of the contractility of the same species are always in
the brain. If it be so, as the ganglions are very numerous, we can
understand why the forces of organic life do not refer, like those
of animal life, to a common centre.
It is evident from these considerations, that there is no great
sympathetic nerve, and that what has been designated by this word
is only an assemblage of small nervous systems, with distinct
functions, but with communicating branches.
We see then what should be thought of the disputes of anatomists
respecting the origin of this pretended nerve, placed in the fifth,
sixth pair, &c. in those of the neck, back, &c.
Many physiologists have entertained concerning the ganglions
opinions similar to those which I have now offered, by considering
these bodies as small brains; but it is essential that these
opinions should enter into the description, which, as it is now
made, gives a very inaccurate idea both of these nervous centres
and of the nerves which go off from them.
The expression of _nervous branches giving origin to such or such a
ganglion_, &c. resembles that in which we should consider the brain
as arising from the nerves of which it is itself the origin.
CHAPTER VII.
GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO VITAL POWER.
The greater number of Physicians, who have written upon the vital
properties, have begun by researches on their principle, have
endeavoured to descend from the knowledge of the nature of this
principle to that of its phenomena, instead of ascending from
observation to theory. The Archæus of Van Helmont, the soul of
Stahl, the vital principle of Barthez, the vital power of others,
have each in their turn been considered as the sole centre of every
action possessing the character of vitality, have each in their
turn been made the common base of every physiological explanation.
But these bases have every one of them been sapped, and in the
midst of their wrecks have remained the facts alone which rigorous
experiment has furnished upon the subject of sensibility and
motility.
So narrow indeed are the limits of the human understanding, that
the knowledge of first causes has almost always been interdicted.
The veil, which covers them envelops with its innumerable folds
whoever attempts to rend it.
In the study of nature, principles are certain general results of
first causes, from whence proceed innumerable secondary results.
The art of finding the connexion of the first with the second is
that of every judicious mind. To seek the connexion of first causes
with their general effects is to walk blindfold in a road from
whence a thousand paths diverge.
Of what importance besides to us are these causes? Is it necessary
to know the nature of light, of oxygen and caloric to study their
phenomena? Without the knowledge of the principle of life, cannot
we analyze its properties? In the study of animals let us proceed
as modern metaphysicians have done in that of the understanding.
Let us suppose causes, and attach ourselves to their general
results.
I. _Difference between vital power and physical law._
In considering the powers of life, we shall perceive in the first
place a remarkable difference between them and the laws of physics.
The first incessantly vary in their intensity, in their energy, in
their development, are continually passing from the last degree of
prostration, to the highest pitch of exaltation, and assume under
the influence of the most trifling causes a thousand modifications;
for the animal is influenced by every thing which surrounds him;
he wakes, he sleeps, reposes or exercises himself, digests, or
is hungry, is subject to his own passions, and to the action of
foreign bodies. On the contrary the physical laws are invariable,
the same at all times, and the source of a series of phenomena at
all times similar. Attraction is a physical power; it is always in
proportion to the mass of brute matter in which it is observed;
sensibility is a vital power, but in the same mass of matter, in
the same organic part its quantity is perpetually changing.
The invariability of the laws which preside over the phenomena of
physics, enables us to apply the formula of calculation to all the
sciences, which have them for their object. Applied to the actions
of the living body, the mathematics can never give us formula.
The return of a comet, the resistance of a fluid in traversing an
inert canal, the rapidity of a projectile may be calculated; but
to calculate with Borelli the force of a muscle, with Keil the
velocity of the blood, with Jurine and Lavoisier the quantity of
air, which enters into the lungs, is to build upon a quicksand, an
edifice solid of itself, but necessarily decreed to fall for want
of a foundation.
This instability of the vital powers, this disposition, which they
continually have to change, impress upon all the physiological
phenomena a character of irregularity which particularly
distinguishes them from those of physics. The latter forever the
same, are well known when once they have been analyzed; but who can
say that he knows the former, because he has analyzed them under
the same circumstances, a multitude of times. The urine indeed,
the saliva, or the bile indifferently taken from such or such a
subject, may be analyzed, and hence results our animal chemistry;
but such a chemistry is the dead anatomy of the fluids, not a
physiological chemistry. The physiology of the fluids should be
composed of the innumerable variations which they experience
according to the different states of their respective organs.
The urine after taking food is not the fluid, which it is after
sleeping; it contains in winter, principles which are foreign to
it, during summer, when the principal excretions are made by the
skin. The simple passage from heat to cold, in suppressing sweat,
and the pulmonary exhalation, will change its composition. The same
is true of the other fluids; the state of the vital powers in the
organs, which are the sources of them, changes at every moment; and
therefore, the secreted substances, which entirely depend upon the
mode of action in the organs, must be as various.
Who will venture to assert, that he knows the nature of a fluid
of the living economy if he has not analyzed it in the infant, in
the adult, and the aged, in the male and in the female, at every
season, during the calm of the mind, and the storm of the passions,
which so manifestly influence its nature? To know such fluid
perfectly, will it not be requisite also to examine the different
alterations of which it is susceptible in consequence of disease?
The instability of the vital powers, is the quicksand on which have
sunk the calculations of all the Physicians of the last hundred
years. The habitual variations of the living fluids, dependent on
this instability, one would think should be no less an obstacle to
the analyzes of the chemical physicians of the present age.
From this reasoning it is easy to perceive, that the science of
organized bodies should be treated in a very different manner
from that of inorganic bodies. To the former a different language
almost is requisite; for the greater number of the words, which we
transfer from the physical sciences, into those of the animal or
vegetable economy, incessantly recall ideas, which are by no means
consistent with their phenomena.
Had physiology been cultivated by men before physics, I am
persuaded that many applications of the former would have been made
to the latter; rivers would have been seen to flow from the tonic
action of their banks, crystals to unite from the excitement, which
they exercise upon their reciprocal sensibilities, and planets to
move because they mutually irritate each other at vast distances.
All this would appear unreasonable to us, who think of gravitation
only in the consideration of these phenomena; and why should we not
in fact be as ridiculous when we come with this same gravitation,
with our affinities and chemical compositions, and with a language
established upon their fundamental data to treat of a science, with
which they have nothing whatsoever to do. Physiology would have
made a much greater progress, if all those who studied it, had set
aside the notions which are borrowed from the accessary sciences,
as they are termed. But these sciences are not accessary; they are
wholly strangers to physiology, and should be banished from it
wholly.[18]
Physics and chemistry are related to each other in many points,
because the same laws in a variety of instances preside over the
phenomena of both of them; but an immense interval divides them
from the science of organic bodies; because a very great difference
exists between the laws which are proper to them, and those of
life. To say that physiology is made up of the physics of animals,
is to give a very inaccurate idea of it; as well might we say that
astronomy is the physiology of the stars.
But the present digression has already been much too long. We shall
now consider the vital powers with respect to the two lives of the
animal.
II. _Difference between the vital properties and those of texture._
In examining the properties of every living organ, we may
distinguish them into two kinds. Those of one kind are dependent
immediately upon life, begin and finish with it, or rather form its
principle and its essence. Those of the other are connected with it
only indirectly, and appear rather to depend upon the organization
and texture of the parts of the body.
The faculties of perceiving and spontaneously contracting are vital
properties: extensibility, and the faculty of contraction upon the
cessation of the extending power, are properties of texture; the
latter it is true, are possessed of a greater energy when existing
in the living fibre, but they remain with the organ when life has
ceased; the decomposition of the organs, is the term of their
existence. I shall first examine the vital properties.
III. _Of the two kinds of sensibility; of the animal and organic
sensibilities._
It is easy to perceive, that the vital properties can be only
those of perception and motion, but in the two lives they possess
a very different character. In the organic life, sensibility is
the faculty of receiving an impression; in the animal life, it is
the faculty of receiving an impression and moreover of referring
such impression to a common centre.[19] The stomach is sensible to
the presence of aliments, the heart to the stimulus of the blood,
the excreting tube to the contact of the fluid, which is peculiar
to it; but the term of this sensibility is in the organ itself. In
the same way do the eyes, the membranes of the nose and the mouth,
the skin, and all the mucous surfaces, at their origin, receive
an impression from the bodies which are in contact with them, but
they afterwards transmit such impression to the brain, which is the
general centre of the sensibility of these organs.
There is an animal sensibility then, and an organic sensibility.
Upon the one depend the phenomena of digestion, circulation,
secretion, exhalation, absorption, and nutrition. It is common
to the plant, and the animal; the Zoophyte enjoys it as perfectly
as the most perfectly organized quadruped. On the other depend
sensation and perception, as well as the pain and pleasure which
modify them. The perfection of animals, if I may so speak, is
in proportion to the quantity of this sensibility, which has
been bestowed upon them. This species of sensibility is not the
attribute of vegetable life.
The difference of these two kinds of sensitive power is
particularly well marked in the manner of their termination, in
the case of violent and sudden death. In such case, the animal
sensibility is at once extinguished; there can no longer be found
any trace of it at the moment which succeeds to strong concussion
of the brain, to great hæmorrhage or asphyxia; but the organic
sensibility survives such accidents more or less. The lymphatics
continue to absorb, the muscle is still sensible to stimuli, the
nails and the hair continue to be nourished, and in consequence
are sensible of the fluids which they imbibe.[20] It is often
a considerable time before all traces of this sensibility are
effaced; the annihilation of the other is instantaneous.
Though at the first glance, the two sensibilities present us so
remarkable a difference, their nature nevertheless appears to be
essentially the same. The one perhaps is only the maximum of the
other, is the same force, but according to its intensity is shown
under different characters. Of this the following observations are
proofs.
There are different parts in the economy, where these faculties
are concatenated, and succeed each other insensibly. The origin of
all the mucous membranes is an example of such parts. We have the
sensation of the passage of aliments in the mouth, and the back
part of it; this sensation becomes weaker at the beginning of the
œsophagus, decreases still towards its middle, and disappears at
its end, as well as in the stomach, where the organic sensibility
only remains. The same phenomena may be observed in the urethra,
&c. In the neighbourhood of the skin, the animal sensibility
exists; it gradually diminishes, however, and becomes organic in
the interior of the system.
Divers excitants applied to the same organ may alternately produce
the one, and the other mode of sensibility. When irritated by
acids, by very concentrated alkalies, or by a cutting instrument,
the ligaments do not transmit to the brain the very strong
impression which is made upon them, but if they be twisted,
distended or rent, a lively sensation of pain is the result.[21]
I have established this fact by a number of experiments in my
treatise on the membranes. The following is another of the same
kind, which I have since observed. The parietes of the arteries
as we know are sensible to the blood by which they are traversed,
but at the same time are the term of this sentiment. If a fluid,
however, which is foreign to this system, be injected into it, the
animal will immediately discover by his cries, that he is sensible
of the presence of such fluid.[22]
We have seen that it is a property of habit, to weaken the
sentiment, to transform into indifferent sensations all those of
pleasure, or of pain. Foreign bodies, for example, will make upon
the mucous membranes a painful impression during the first days
of their application to it; they develop in such parts the animal
sensibility, but by little and little this sensibility decreases,
and the organic alone subsists. In this way the urethra is sensible
of the bougie as long as it continues there, for during the whole
of such time, the action of the mucous glands of the passage
is augmented, from whence arises a species of catarrh, but the
individual for the first moments only had a painful consciousness
of the presence of the instrument.
We every day observe, that inflammation in exalting the organic
sensibility of a part, transforms the organic into the animal
sensibility: the cartilages thus, and the serous membranes which
in their ordinary state have only the obscure sentiment, which
is necessary to their nutrition, in an inflammatory state are
possessed of an animal sensibility, which is frequently stronger
than that of the organs to which it is natural. And why? Because
the essence of inflammation consists in accumulating the powers of
the part, and this accumulation suffices for changing the mode of
the organic sensibility, which differs from the animal sensibility
in quantity only.
From these considerations it is evident that the distinction above
established with respect to sensibility consists in the different
modifications of which this power is susceptible, and not in its
nature, which is every where the same. This faculty is common to
all the organs; they are all of them possessed of it; it forms
their true vital character; but more or less abundantly distributed
to each, it gives to each a different mode of existence. No two
parts enjoy it in the same proportion. In these varieties there is
a degree, above which the brain is the term of it, beneath which
the organ alone is sensible of the impression.
If to render my ideas on this head more clear I were to use
a vulgar expression, I should say that distributed in such a
dose to an organ, sensibility is animal: in such another dose,
organic.[23]--Now that, which varies the dose of sensibility, is
sometimes the order of nature, (in which way the skin and the
nerves are more sensible than the tendons, and cartilages;) at
other times, disease; thus in doubling the dose of sensibility to
the cartilages inflammation renders them equal in this respect, and
even superior to the former, and as a thousand causes may at every
moment exalt or diminish this power in any part of the body it may
be changed at every moment from the animal to the organic type.
Hence the reason, why authors, who have made it the object of their
experiments, have come to results so different; and why some of
them have observed the periosteum and dura mater to be insensible,
while others have put them down on the contrary as endowed with an
extreme sensibility.
IV. _Of the relation which exists between the sensibility of each
organ, and foreign bodies._
Although the sensibility of each organ be subject to continual
variations, it is nevertheless distributed to each by nature in a
determined quantity; in a quantity to which it ever returns after
its alternations of augmentation or decrease. In this respect it
resembles the pendulum, which in each of its different oscillations
resumes the place to which it is brought down by gravitation.
It is this determined sum of sensibility, which especially composes
the life of each organ, and fixes the nature of its relations with
foreign bodies; in this way the ordinary sum of sensibility in the
urethra fits it for the passage of the urine, but if this sum be
augmented, as in strong erection of the penis, the above relation
ceases: the canal refuses passage to the urine, and suffers itself
to be traversed by the semen only, which in its turn has no
relation with the sensibility of the urethra when the penis is not
erected.[24]
From hence proceeds the reason of the puckering up and spasm of
the parotid, the cystic, and pancreatic ducts, as well as of the
excreting tubes in general, when the molecules of any other fluid
than that, which they are destined to convey are presented to them.
The sum of their sensibility corresponds exactly with the nature
of their respective fluids, but is disproportioned to that of any
other.[25]--The spasmodic contraction of the larynx when irritated
by any foreign body is produced in the same manner; for the same
reason the ducts, which open upon the mucous surfaces, though
at all times in contact with a variety of different fluids, are
never penetrated by them.[26] The mouths of the lacteals, however
patulous within the alimentary canal, will take up the chyle only,
they reject the fluids, which are mixed with it; for with these
their sensibility has no relation.
Such relations do not exist only between the different sensibility
of the organs, and the different fluids of the body; but they may
be exercised also between exterior substances, and the various
parts of the living system. The sum of sensibility in the bladder,
the kidneys and the salivary glands has a peculiar analogy with
cantharides and mercury. It might be thought that the sensibility
of each organ is modified, that it assumes a peculiar nature,
and that it is this diversity of nature, which constitutes the
difference of the relations of the organs with regard to bodies in
contact with them; but a number of considerations tend to prove
that such difference is occasioned, not by any difference in the
nature, but in that of the sum, the dose, the quantity of the
sensibility, if such words may be applied to a living property. I
shall adduce the following instances:--
The absorbent orifices of the serous surfaces, are sometimes bathed
for months together in the fluid of dropsies, and take up nothing.
But if the sensibility of these orifices be exalted by tonics, or
an effort of nature, in such case it will place itself, if I may so
say, in equilibrium with the fluid, and absorption will be made.
The resolution of tumours presents us with the same phenomena; as
long as the powers of the parts are weakened, the lymphatics refuse
admittance to the extravasated substances; but if the sum of these
powers be augmented by the use of resolvents, in a short time, from
the action of the lymphatics, the tumour will disappear: from the
same cause the blood, and other fluids are taken up with a sort of
avidity at times, and at others, not at all.[27]
The art of the physician, then, in the use of resolvents, must
consist in ascertaining the degree of sensibility which he
requires in the vessels for the purpose which he has in view; and
in exalting or depressing this power accordingly. In this way, in
different circumstances, resolvents may be taken from the class of
the debilitating or stimulating remedies.
The whole of the theory of inflammation is connected with the
above ideas. It is well known that the system of the canals,
which circulate the blood gives birth to a number of other small
vessels, which admit only the serous part of this fluid. Why do
not the red globules pass into the serous vessels, though there
exist a continuity of canal? The cause by no means consists in
the disproportion of the vessels to the globules as Boerhaave
has taught. The breadth of the white vessels might be double or
triple that of the red vessels, and still the globules of the
latter colour would not pass into them, if there were not to exist
a relation between the sum of the sensibility of the vessels,
and the nature of the globules. Neither will the chyme pass into
the Choledochus, though the diameter of this canal be very much
larger, than that of the attenuated molecules of the aliments. Now
in the healthy state, the quantity of sensibility in the white
vessels being inferior to that in the red ones, it is evident that
the relation necessary to the admission of the coloured globules
cannot exist. But if any cause should exalt their powers, their
sensibility will be on a par with that of the latter set of
vessels, and the passage of the fluids till then refused, will take
place with facility.
Hence it happens, that those surfaces, which are the most exposed
to such agents as exalt the sensibility, are also the most subject
to local inflammation, as may be remarked in the conjunctiva
and the lungs; at which time such is usually the increase of
sensibility in the part, that of organic, which it was, it becomes
animal, and transmits to the brain the impressions, which are made
upon it.
Inflammation lasts as long as there subsists an excess of
sensibility; by degrees it diminishes, the red globules cease to
pass into the serous vessels and resolution takes place.
From this it may be seen that the theory of inflammation is only a
natural consequence of the laws, which preside over the passage of
the fluids into their respective tubes; hence also it may be easily
conceived how unfounded are all hypotheses, which are borrowed from
hydraulics, a science, which never can be really applied to the
animal œconomy, because there is no analogy between a set of inert
tubes, and a series of living ducts.[29]
I should never have finished were I to enumerate the consequences
of this principle in the phenomena of the living man. The reader
will easily enlarge the field of these consequences, the whole of
them will form almost all the great data of physiology, and the
essential points of the theory of diseases.
But no doubt it will be asked, why the organs of the internal life
have received from nature, an inferior degree of sensibility only,
and why they do not transmit to the brain the impressions, which
they receive, while all the acts of the animal life imply this
transmission? the reason is simply this, that all the phenomena,
which establish our connexions with surrounding objects ought to
be, and are in fact under the influence of the will; while all
those, which serve for the purpose of assimilation only, escape,
and ought indeed to escape such influence. Now for a phenomenon to
depend upon the will, it is evidently requisite that the individual
be possessed of a consciousness of such phenomenon, to be withdrawn
from the influence of the will, there should exist no such
consciousness.
V. _Of the two kinds of contractility, the animal, and the organic
contractility._
Contraction is the ordinary medium, by which the motion of the
animal organs is effected; some parts, however, move by dilating
themselves, as the iris, the corpora cavernosa, the teat and
others; so that the two general faculties, from whence spontaneous
motion is derived, are contractility and active extensibility; the
latter of these should be carefully distinguished from passive
extensibility, of which in a short time we shall speak. The first
is a property of life, the second a property of texture; but as yet
there exist too few data upon the nature and mode of the motion
resulting from the former; it is exemplified in too small a number
of organs, for us to be enabled to pay much attention to it in
these general considerations--Accordingly we shall occupy ourselves
only upon the subject of contractility; with respect to that of
active extensibility, I refer to the writings of the physicians of
Montpellier.
Spontaneous motility, a faculty inherent in living bodies, as
well as sensibility, possesses two great modifications, which
differ very much from each other, accordingly as it is examined
in the phenomena of one or the other life. There is an animal
contractility, and there is an organic contractility.
The one being essentially subject to the influence of the will,
has its principle in the brain, receives from the brain the
irradiations, which put it in action, and ceases to exist when
the organs, in which it is observed, communicate no longer with
the brain; it participates besides at all times with the state of
the brain, has exclusively its seat in the voluntary muscles, and
presides over locomotion, the voice, the general movements of the
head, the thorax and abdomen. The other, which is not dependent
on a common centre, has its principle in the moving organ itself,
is a stranger to the influence of volition, and gives rise to the
phenomena of digestion, circulation, secretion, absorption, and
nutrition.
The two are quite distinct in all cases of violent death; such
death annihilates at once the animal contractility, and allows,
for a longer or shorter time, the organic contractility to be
exercised; they are essentially distinct also in all cases of
asphyxia; in these, the first is entirely suspended, the second
remains in activity; lastly they are distinct both in artificial
palsy and in that which is brought on by disease. In these, the
voluntary motions cease; the organic motions are unaltered.
Both the one and the other kind of contractility are connected with
their corresponding kinds of sensibility. They are a consequence of
them. The sensation of external objects puts in action the animal
contractility; before the organic contractility of the heart can be
exercised, its organic sensibility must be excited by the influx of
blood.
Nevertheless, the concatenation of these two kinds of faculties
is not always the same. The animal sensibility may be exercised,
and not be necessarily followed by the exercise of its analogous
contractility. There is a general relation between sensation and
locomotion, but this relation is not direct and actual. On the
contrary, the organic contractility can never be separated from the
sensibility of the same species; the re-action of the excreting
tubes is immediately connected with the action, which the secreted
fluids exercise upon them: the contraction of the heart must
necessarily succeed the influx of the blood into it. But authors
have by no means separated these two things, either in their
considerations or their language. Irritability denotes at the same
time the sensation excited in the organ from the contact of bodies,
and the contraction of the organ in reacting upon its excitants.
The reason of this difference in the relation of the two
sensibilities and contractilities to each other is very simple. In
the organic life, there is nothing intermediate in the exercise
of these two faculties. The same organ is the term, in which the
sensation ends, and the principle from whence the contraction
begins. In the animal life, on the contrary, there exists between
these two acts two intermediate functions, those of the brain
namely, and the nerves, and these by not being brought into action
may interrupt the relation in question.
To the same cause must we refer the following observation. In the
organic life there always exists a rigorous proportion between the
sensation, and the contraction. In the animal life the one may be
exalted or lowered, and the other not affected by such change.
VI. _Subdivision of the Organic contractility into two
Varieties._[30]
The animal contractility is always the same in whatever part of the
body it is situated. But there exist in the organic contractility
two essential modifications, which would seem to indicate a
difference in their nature, though there be only diversity in
outward appearances. This difference is sometimes visible, at other
times though really existing, it cannot be seen by inspection.
The sensible organic contractility may be observed in the heart,
in the stomach, intestines, bladder,[31] and other organs. It is
exercised upon very considerable quantities of the animal fluids.
The insensible organic contractility is that, by virtue of which
the excreting tubes re-act upon their respective fluids, the
secreting organs upon the blood, which flows into them, the parts
where nutrition is performed upon the nutritive juices, and the
lymphatics upon the substances which excite their open extremities;
upon all these occasions, wherever the fluids are disseminated in
small quantities, or are very much divided, this second species
of contractility is brought into exercise. A tolerably precise
idea may be given of both, by comparing the one with attraction, a
power which is exercised upon the great aggregate of matter, and
the other with the chemical affinities, the phenomena of which take
place in the molecules of different substances. For the purpose of
explaining this difference, Barthez has compared the one to the
second hand of a watch, which traverses the circumference in a very
apparent manner, and the other to the hour hand, which moves also,
but whose motion is not distinguishable.
The sensible organic contractility nearly answers to the
irritability of authors; the insensible organic contractility to
what is called tonicity. But these words seem to suppose in the
properties, which they indicate a difference of nature, while this
difference exists only in appearance. I therefore prefer employing
for both a common term. It designs their general character, that
of appertaining to the interior life, and their independence with
regard to the will. To this term I join an adjective expressive of
the particular attribute of each.
In fact we should possess a very inaccurate idea of these two modes
of action, were we to consider them as proceeding from different
principles. The one is but the extreme of the other; they are
both connected by insensible gradations. Between the obscure but
real contractility, which is necessary to the nutrition of the
nails, and the hair, &c. and that which we see in the motions of
the stomach, and intestines, there exist innumerable shades of
this property, which serve as transitions betwixt its perceptible
degrees; such are the motions of the dartos,[32] of the arteries,
and of certain parts of the cutaneous organs.
The circulation will give us a very good idea of this graduated
enchainment of the two kinds of organic contractility. The sensible
organic contractility presides over this function in the heart
and large vessels,[33] by degrees it become less apparent, in
proportion as the diameter of the vascular system decreases; and
lastly, it is insensible in the capillary tubes, where tonicity
only is observed.
Should we consider irritability as a property inherent exclusively
in the muscles, as being one of the characters by which they are
distinguished from other organs, and should we call this property
by a name expressive of its peculiar seat in the muscle, we should
conceive it, if I mistake not, in a very different way from that in
which it naturally exists.
It is true, that in this respect the muscles occupy the first
rank in the scale of the animal solids; they possess the maximum
of the organic contractility; but every living organ acts, as
they do, though in a manner less apparent upon the excitant when
artificially applied, or on the fluid, which in the natural way is
carried to it for the purpose of supplying the matter of secretion,
nutrition, exhalation, or absorption.
Nothing in consequence is more uncertain than the rule, which
is commonly adopted for pronouncing upon the muscularity of any
doubtful part; for the rule consists in ascertaining whether such
part does or does not contract under the action of stimuli.
It is thus, that a muscular tunic is admitted in the arteries,
although their organization entirely differs from that of the
muscles; it is thus, that the womb is pronounced to be fleshy,
however foreign to such structure; it is thus, that a muscular
texture is admitted in the dartos, in the iris, and other parts,
although no such structure be observable there.
The faculty of contracting under the action of irritating
substances like that of the sensibility, is unequally distributed
among the organs; they enjoy it in different degrees. We do not
properly conceive it, if we suppose that it belongs exclusively
to some of them. It does not, as some have imagined, possess its
peculiar seat in the muscular fibre. Life is the sole condition
necessary to all the fibres for enjoying it; their peculiar texture
influences the sum only, which they receive of it; it appears that
to such an organic texture, is attributed, if I may so express
myself, such a dose of contractility; to such another texture, such
another dose, and so on; so that to employ the expressions, which
I have used in treating on the subject of sensibility (however
improper they may be, yet capable alone of rendering my ideas)
the differences in the organic contractility of our different
parts, consist in the quantity only, and not in the nature of this
property: indeed it is with respect to quantity only that this
property varies, accordingly as it is considered in the muscles,
the ligaments, the nerves, or the bones.
If a special mode of contraction ought to be designed for the
muscles by a particular expression, such expression could be only
derived from the property which they have of contracting from
the influence of the will; but this property is foreign to their
texture, and comes to them from the brain only; for as soon as
they cease to communicate with this organ directly by means of the
nerves, they cease also to be the agents of voluntary motion.
These considerations lead us to examine the limits which are placed
between the one and the other kind of contractility. We have seen
that those which distinguish the two modes of sensibility, appear
to be derived only from the greater or less proportion of this
power; that in a certain proportion sensibility is of the animal
kind, in a certain inferior proportion, of the organic kind, and
that frequently from an augmentation, or diminution of intensity
the two sensibilities reciprocally borrow their respective
characters. We have seen a phenomenon almost analogous to this in
the two subdivisions of the organic contractility.
But this is not the case with regard to the two great divisions
of contractility considered in general. The organic can never
be transformed into the animal contractility. Whatever be its
increase of energy, it constantly remains the same in its nature.
The stomach, the intestines frequently assume a susceptibility
of contraction, which makes them rise up and produces in
them[34] the most violent motions by the most simple stimuli,
but these movements preserve at all times their peculiar type,
their primitive character; and have never been regulated by the
brain. From whence proceeds this difference in the phenomena of
sensibility and contractility? I cannot in a precise and rigorous
manner resolve this question.
VII. _Of the extensibility and contractility of texture._
I shall now proceed to examine the properties, which depend on
texture only, on the organic arrangement of the fibres of the
different parts. These are extensibility and contractility.
They both succeed each other, and are connected in the same way, as
in the vital phenomena, the organic and animal sensibilities are
related to their respective contractilities.
Extensibility of texture, or the faculty of being distended
beyond the ordinary state by external impulse (and in this it
is distinguished from the extensibility of the iris,[35] the
corpora cavernosa, &c.) This extensibility, I say, belongs to
many organs. The extensor muscles are very much lengthened in
strong tension of the limbs; the skin accommodates itself to
tumours; the aponeuroses, as we see in ascites and pregnancy, are
distended by what is accumulated beneath them. The mucous membranes
of the intestines, of the bladder; the serous membranes of the
greater number of the cavities present us with similar phenomena,
when these cavities are full. The fibrous membranes, the bones
themselves are susceptible of distension. Thus in hydrocephalus the
pericranium, and the bones of the cranium, in spina ventosa and
other analogous diseases, the extremities or the middle of the long
bones experience a similar distension. The kidneys, the brain, and
the liver, when abscesses are formed in their interior, the spleen
and the lungs, when penetrated by a great quantity of blood, the
ligaments in articular dropsies, in short all the organs, under
a thousand different circumstances, exemplify this property; a
property inherent in their texture, and not precisely depending on
their life; for as long as their texture remains untouched, their
extensibility subsists also, though they themselves have ceased
to live.--The decomposition of the part, from whatever cause it
happens, is the sole term of this extensibility, in which the
organs are passive at all times, and subject to the mechanical
influence of those bodies which act upon them.
There exists for the different organs a scale of extensibility,
at the top of which are those which have the greatest laxity in
the arrangement of their fibres, as the muscles, the skin, and
cellular substance; at the bottom of the scale are those which are
characterized by their density, as the bones, the cartilages, the
tendons, and the nails.
We must not, however, be deceived by appearances, with regard to
the extensibility of parts of the body; for the serous membranes,
which at the first glance would seem to be capable of great
distension, do not yield so much of themselves, as from the
development of their folds. Thus the displacement of the skin,
which abandons certain parts, while it spreads over tumours in the
vicinity, might easily give rise to the supposition of its being
capable of a much greater distension than that of which it is
really susceptible.
With extensibility of texture, there corresponds a certain mode of
contractility, which may be designated by the name of contractility
of texture. This can only take place after a previous distension.
In general the greater number of our organs are maintained in a
certain degree of tension from different causes; the locomotive
muscles by their antagonists, the hollow muscles by the different
substances which they enclose; the vessels by the fluids,
which circulate within them, the skin of a part by that of the
neighbouring parts, the alveolar parietes by the teeth which they
contain. If these causes be removed, contraction supervenes; thus,
if a long muscle be cut, its antagonist will be shortened; if
a hollow muscle be emptied, it will contract; if an artery be
deprived of its blood, it will become a ligament; if the skin be
cut into, the borders of the incision will retire from each other;
if a tooth be drawn, its cavity will be obliterated.
In these cases it is the cessation of the natural extension, which
occasions the contraction; in other cases it is the cessation of
an unnatural extension which does so. Thus, the lower belly is
straitened after puncture or delivery; the maxillary sinus, after
the extirpation of a fungus; the cellular texture, after the
opening of an abscess, the tunica vaginalis, after the operation
of hydrocele, the skin of the scrotum, after the extirpation of
the voluminous testicle, by which it was distended; the sac of an
aneurism, after the evacuation of the fluid.
This mode of contractility is not by any means dependent on life;
it belongs only to the texture, to the organic arrangement of the
part,[36] yet still receives from the vital powers an increase
of energy. Thus the retraction of a muscle, which is cut in the
dead subject, is much smaller than that of a muscle divided in the
living animal; in the same way, the retraction of the skin varies;
but though less evident, this contractility subsists always, and
like its corresponding extensibility has no other limit than that
of the decomposition of the part.
The greater number of authors have confounded the phenomena of this
contractility with those of the insensible organic contractility,
or tonicity. Of these I might reckon Haller, Blumenbach, Barthez
and others, who have referred to the same principle the return
upon themselves of the abdominal parietes, after distension, the
retraction of the skin, or a divided muscle, and the contraction
of the dartos from cold. The first of these phenomena is owing to
the contractility depending on texture, which does not suppose the
application of an irritating substance; the second, to tonicity,
which is never exercised excepting when influenced by such
application.
Neither have I myself, in my treatise on the membranes,
sufficiently distinguished these two modifications of contraction,
but we evidently ought to establish between them the most decided
limits.
An example will render this more sensible. Let us take for
it an organ, in which there may be observed all the kinds of
contractility, of which I have hitherto spoken; a voluntary muscle
for instance: In distinguishing the species with precision we may
acquire a clear and precise idea of each of them.
Now such muscle may enter into action first by the influence of
the nerves, which it receives from the brain; here it shews its
animal contractility. Secondly, it may be brought into action by
the stimulus of a physical or chemical agent applied to it, a
stimulus, which artificially creates a motion, analogous to that,
which is natural to the heart, and other involuntary muscles;--here
we have the sensible organic contractility or irritability.
Thirdly, its action may be produced by the influx of fluids, which
penetrate all its parts for the purpose of carrying thither the
matter of nutrition, and which at the same time are the occasion
of a partial oscillatory movement in each fibre, in each molecule,
a movement as necessary to the function of nutrition, as in the
glands it is indispensable to the process of secretion, or in the
lymphatics to that of absorption.[37] Such action we refer to the
insensible organic contractility or tonicity: Fourthly, by the
transverse section of the substance or body of the muscle, may be
determined the retraction of its two ends towards their points of
insertion. Here the contractility of its texture is displayed.
Any one of these kinds of contractility may cease to exist in
a muscle and the others may not be affected. Cut its nerves,
and there will be no longer any animal contractility; but the
two modifications of its organic contractility will continue to
subsist. Impregnate the muscle with opium, suffer its vessels to be
well penetrated with this substance and it will cease to contract
under the impression of stimuli, it will lose its irritability,
but it will continue to possess the tonic movements, which are
occasioned by the influx of blood into it. Lastly, kill the animal,
or rather let it live, but tie the vessels which go to the limb,
and the muscle will in such case lose its tonic power and possess
its contractility of texture only. The latter will only cease on
the supervention of sphacelus.
By these examples the different kinds of contractility may be
appreciated with respect to the organs where they are assembled
in a smaller number than in the muscles of volition; in the heart
for instance and in the intestines, where there exists a sensible
and insensible contractility, the organic being retrenched; and
again in the tendons, aponeuroses, and bones, where the animal
and sensible organic contractilities are wanting, the insensible
organic and the contractility of texture only remaining.
In general these two last are inherent in every kind of organ,
the two first belonging to some in particular only; hence for the
general character of living parts we must choose the insensible
organic contractility or tonicity, and for the character of
all organized parts whatsoever, whether living or dead, the
contractility of texture.[38]
We shall farther remark, that this last in the same way as its
corresponding extensibility possesses them, has its different
degrees, its scale of intensity, the skin and the cellular
substance on the one hand, the tendons, the aponeuroses, and the
bones on the other, forming the extremes of this scale.
From all that has been said, it is easy to perceive, that in the
contractility of every organ there are two things to be considered,
namely the contractility, or the faculty, and the cause, which puts
it in action. The contractility is always the same, belongs to
the organ, is inherent in it, but the cause which determines its
exercise may be various.
VIII. _Recapitulation of the properties of living bodies._
A recapitulation of these properties may be seen in the following
table:
_Properties._
_Classes._ _Genera._ _Species._ _Varieties._
{ { 1st Animal
{ 1st Sensibility-- {
{ { 2d Organic
1st Vital-- {
{ { 1st Animal
{ 2d Contractility--{ { 1st Sensible
{ { 2d Organic--{
{ 2d Insensible
{ 1st Extensibility
2d of Texture-- {
{ 2d Contractility
I have not inserted in this table that modification of motion,
which takes place in the iris, the corpora cavernosa, &c. a
motion, which precedes the influx of the blood, and which is not
in such way occasioned, neither have I mentioned the dilatation
of the heart,[39] and in a word that species of active and vital
excitability, of which some parts appear to be susceptible, and my
reason for this neglect, although I recognise the reality of the
modification, is my want of clear and precise ideas on the subject.
From the properties, which I have now explained, are derived all
the functions, all the phenomena, which are exemplified in the
living œconomy. There is not one, which may not be traced to them
after a strict analysis, in the same manner as in the phenomena of
physics we recur to the properties of attraction, elasticity, &c.
Wherever the vital properties are in action, there is a
disengagement, and a loss of caloric peculiar to the animal, which
compose for him a temperature independent of the medium in which he
lives. The word caloricity will hardly serve for the expression of
this fact, which is a general effect of the two great vital powers
in a state of action, and not produced by any especial faculty
distinct from them. We do not make use of the words, digestibility,
or respirability, because digestion and respiration are the results
of functions derived from the common laws of the system.
For the same reason the digestive power of Grimaud suggests an
inaccurate idea. The assimilation of heterogeneous substances to
our organs, is not the effect of any peculiar power. The same
may be said of the different principles admitted by a number of
authors, who have attributed to results and functions denominations
expressive of laws, and vital properties.
The proper life of each organ is composed of the different
modifications, to which are submitted in each of them the vital
sensibilities and mobilities, modifications, which invariably are
productive of others in the circulation and temperature of the
organ. Let it be noticed however, that each organ independently of
the general sensibility, mobility, temperature, and circulation of
the body, has a particular mode of sensation and heat, together
with a capillary circulation, which being withdrawn from the
influence of the heart, receives the influence only of the tonic
action of the part.[40] But we may pass over a point so frequently
and sufficiently discussed by other authors.
Let it here be understood that I offer what I have said on the
subject of the vital powers, only as a simple view of the different
modifications, which they experience in the two lives. These
detached ideas will in a short time form the basis of a more
extensive work.
Neither have I recapitulated the different divisions of the vital
powers, which have been adopted by authors; the reader will find
them in their works, and will easily perceive the differences,
which distinguish them from those, which I have adopted. I shall
only observe that were these divisions clear and precise, did they
suggest to all the same meaning, we should not have to regret in
the writings of Haller, Lecat, Wyth, Haen, and all the physicians
of Montpellier, a number of disputes of no importance to the
interest of science, and surely fatiguing to the student.
FOOTNOTES:
[18] Bichat often complains in his works of the injury that has
been done to the physiological sciences, by the attempts that are
made to facilitate the study of them by means of physics. He was
not competent to decide the question, not having sufficient data
in the sciences, the use of which he reprobated; the most that
he should have said, was that a bad application had been made of
them. Even this reproach was too general to be just. No doubt,
mankind have been led into errors by attempting to support on
slight foundations a science which was still in its infancy; but
even in the time of Bichat it could not be denied that it was to
the progress of these same sciences, that was owing the explanation
of many very important phenomena; that by it was ascertained what
takes place in respiration, and by what means a living body always
supports itself between certain limits of temperature, &c.
[19] It must be remembered that the existence of such a sensibility
is purely conjectural. As it is not transmitted to a common centre,
we can recognize it only by its effects. In order to explain these
effects, there is no need of admitting a similar faculty. This
sensibility moreover, if its existence should be admitted, would
be found continually in fault. The stomach, for example, allows
a substance to go out of its cavity which could never serve for
aliment, provided this substance exhibits a degree of fluidity
approaching that of chyme. The absorbents take up the most noxious
fluids, those even the action of which is sufficiently powerful to
destroy the organization of their parietes; the heart contracts
without the entrance of the blood into it, &c.
[20] This is altogether inaccurate; a nail in growing is not
nourished, any more than the mucus is nourished in the nasal
fossæ, or the urine in the bladder. The nails, the hair on the
various parts of the body and the hair of the head, all in a word
epidermoid productions, are the result of real secretions which
do not differ from the secretions of which we have just spoken,
only in this, that the product instead of remaining fluid like the
urine, or viscid like the mucus, hardens as it comes out of the
secretory organ, like the thread of the silk worm, or that of the
spider. A certain number of these organs is commonly arranged in
such a manner, that the matter secreted by each of them is found
in a fluid state in contact with that of the neighbouring organs,
with which it is agglomerated in hardening. Arranged in concentric
circles around a small cone, they produce a hollow cylinder;
extended in parallel lines upon a broad surface, they produce a
flattened lamina. Such is the manner in which the nails and the
hair are formed. We see from this that the epidermoid productions
grow, but are not nourished. The hair exhibits, it is true, an
internal cavity, filled with a coloured fluid, which appears to be
necessary for its preservation; but we can easily conceive how an
oily fluid may help to preserve it, by giving it suppleness and
thus preventing it from breaking. This fluid is poured into the
canal in which it is found, and it is not the hair which draws it
in, any more at least, than a capillary tube draws in the fluid
into which its extremity is plunged.
[21] The idea of endowing each texture with a peculiar kind of
sensibility in relation with its uses is one which pleases the
imagination. The ligaments are designed to oppose the separation of
the bones; they should remain insensible to every kind of stimulus
that does not tend to disunite these parts, and pain consequently,
should not be produced but from distension or twisting.
Unfortunately this supposition is not well founded, the facts on
which it rests were not accurately observed. It is very true that
in twisting these ligaments, the animal almost always cries out,
but it is because we at the same time stretch some neighbouring
parts endowed with sensibility. When this is prevented and the
experiment is made with proper precaution, we can twist, distend or
tear the ligament, without appearing to give the animal any pain.
[22] So, as long as the fluid is retained in the artery, which is
easily done by means of ligatures, no pain is manifested; but when
the irritating substance is carried by the vessels to the heart or
to any other sensible part, we can easily conceive that the animal
must experience pain, for the irritant always produces its effect,
whether it be carried directly to the part or arrive there by means
of the circulation.
[23] These expressions _dose_, _sum_, _quantity_ of sensibility
are incorrect, inasmuch as they exhibit this vital faculty under
the same point of view as the physical forces, as attraction,
for example; and as they present it to us as susceptible of
calculation, &c.; but, from a want of words for one science, it is
necessary, in order to make it understood, to borrow them from the
other sciences. There are expressions, like the words to _solder_,
to _glue_, to _unglue_, &c. that are used for the want of others in
the osseous system, and which really give very inaccurate ideas,
unless the mind corrects the sense.
[24] If the urine, during a perfect erection, does not go out
of the bladder, it is because the contraction of the muscles of
the perineum, and especially of the levator ani, prevents it. If
these muscles are relaxed, though the turgescence of the corpus
cavernosum and of the urethra remains the same, the urine flows out
without any other obstacle than what arises from the contraction of
the canal produced by the swelling of its parietes.
[25] These different excretory ducts do not exhibit in the mammalia
any contractility. There is no stimulus which can produce it in
them; I have tried them all in vain. In birds, on the contrary,
the ureters and the pancreatic and biliary canals are contractile,
and their motions, which return at intervals, are too well marked
to be mistaken. It appears that the contractility of the excretory
canals in the abdomen, is connected in these animals with the
absence of the diaphragm. We know in fact that this muscle in the
mammalia, assists by the pressure which it exerts, the course
of the secreted fluids, and renders useless the existence of
a peculiar motion in the canals which contain them. If it be
however pretended that this motion exists in them, but that it is
insensible, it must be allowed then, that it cannot perform the
office which is attributed to it, viz. that of obliterating an
opening often large enough to admit a quill. It is true, that if
the orifice of one of these canals be irritated for a long time, a
swelling of the membrane which lines it is sometimes produced, and
the opening is then really lessened. But in these cases there is
no occasion to be deceived; we see that this swelling is produced
at that point by the afflux of the fluids, as it would be in any
other part subjected to a similar excitement. Besides, it should
be observed that the obliquity of insertion of the excretory ducts
is alone sufficient to explain how the substances which pass in
front of their orifices are not introduced into them. In fact
these substances, at the moment of their passage, by the pressure
which they exert, tend to obliterate the opening of the canal,
by flattening its parietes against each other; it is thus that
the pressure of the urine, upon the inferior extremity of the
ureters, prevents this fluid from ascending towards the kidney. The
obliteration of the opening is but an accidental thing, and most
often is not even complete.
[26] It is not surprising, that a canal usually filled with the
excreted fluids should refuse to admit another which runs in an
opposite direction.
[27] All that is here said of the sensibility of the lymphatic
vessels, which makes them sometimes admit and sometimes reject
the effused fluids, is the more hypothetical, as it is not as yet
proved that these vessels are the agents of absorption. It should
be remarked, that the fluids that are supposed to be absorbed by
them, differ essentially in their chemical composition, from the
fluid that is usually found in their cavity. This fluid besides
varies but very little in its composition, though its appearance
is not uniformly the same; now, if it were the result of the
absorption of fluids differing from each other, its composition
ought also to vary as that of the chyle does, according to the
nature of the aliments.
Before the lymphatic vessels were known, the principal phenomena
of absorption were observed, and it was natural to attribute them
to the action of the veins. This opinion was maintained for a long
time after the discovery of the lymphatics. Finally, towards the
middle of the last century, Hunter being engaged in examining these
vessels, which he has done more to make known than any other man,
thought that they should be considered as the agents of absorption,
and this opinion was soon generally admitted. If we look for the
means by which he overthrew the ancient theory, we are astonished
to find that it was by five experiments only. Harvey did not with
equal facility obtain the acknowledgment of the circulation, and
perhaps there does not exist a second example of an opinion, which
was for a long time established, being abandoned so readily. It
should be remarked, that physiologists had not yet recovered from
the surprise produced by the discovery of a system of vessels so
extensive, and yet for so long a time unknown; they were impatient
to know the use of them; the veins had already the function of
returning to the heart the blood brought by the arteries; they
thought it would not impoverish them too much to deprive them of
the faculty of absorbing, in order to enrich the lymphatics with
it. Of the five experiments of Hunter, two are designed to prove
that the veins do not absorb, the object of the other three is to
show that the lymphatics do.
In the first experiment he injected tepid water into a portion of
intestine, and the blood which returned by the vein appeared to be
neither more diluted nor lighter than before. We cannot conceive
how by mere inspection, it is possible to judge if the blood
contains a certain quantity of absorbed water, a quantity which
must be proportionably very small, if we consider the whole amount
of blood that passes through the mesentric veins during the period
necessary for the absorption of the fluid. Hunter in the same
experiment tied the artery which went to the portion of intestine,
and examined the state of the vein. It did not swell, and its blood
did not become aqueous. But after this ligature, did the absorption
continue to go on in this portion of intestine, which still had no
doubt lymphatic vessels? This the author does not say. How moreover
should he think that the vein could continue its action when the
artery was tied?
In the second experiment Hunter injected milk into a portion of
intestine, and was unable to discover this fluid in the blood of
the mesentric veins; but at the period in which this experiment
was made, mankind were very far from being able to detect in the
blood a very small quantity of milk, and at the present day, with
all the aid derived from chemistry, we can hardly discover in
it a small quantity which is mixed directly with it. These two
experiments prove then nothing against the absorption of the veins;
as to those which he brings forward in favour of absorption by the
lymphatics, they are not more conclusive. I shall content myself
with relating one of them. He injected, into a portion of intestine
that was empty, a certain quantity of warm milk, and confined it
there by two ligatures. The veins that came from this portion were
emptied of their blood by several punctures made in their trunk.
The corresponding arteries were tied. He then returned the parts
into the abdomen, and drew them out again in half an hour. Having
examined them with attention, he observed that the veins were
almost empty, and that they contained no white fluid, whilst the
lacteals were almost full of it. But was not this white fluid that
filled them chyle rather than milk? Was it not there before the
injection of this liquid? In order to ascertain what takes place in
the lymphatic vessels during absorption, we must begin by examining
the state of these vessels before the experiment. But this is what
Hunter did not do, and it is this that renders his experiment of
no value. It is not very astonishing that he mistook the chyle
for the milk, since milk has for a long time been mistaken for
chyle. Flandrin, Professor of the Veterinary School at Alfort, has
several times repeated this experiment of Hunter; but he took care
before the injection of the milk to ascertain that the lymphatics
contained no white fluid; and he never found any in their cavity
after the experiment. I have myself many times performed this
experiment, with the same precaution, and I have uniformly obtained
the same results as those of Flandrin.
It would occupy too much time to examine all the reasons that have
been advanced for and against the absorption of the lymphatics; I
shall only relate some experiments I have made myself; but I ought
first to observe, that absorption undoubtedly takes place in parts
such as the eye, the brain, and the placenta in which the most
minute dissection has been unable to discover any lymphatic vessel.
_First experiment._--Four ounces of the decoction of rhubarb was
given to a dog, in half an hour after he was killed, and it was
found that more than half of the liquid had disappeared; the urine
evidently contained rhubarb, but the lymph in the thoracic duct
exhibited no trace of it.
_Second experiment._--A dog swallowed several ounces of alcohol
diluted with water; at the end of a quarter of an hour, the blood
of the animal had a very distinct odour of alcohol, but there was
nothing of the kind in the lymph.
Flandrin made a similar experiment on a horse, to whom he gave half
a pound of assafetida mixed with an equal quantity of honey. Six
hours after, the horse was killed. The odour of the assafetida was
very perceptible in the blood of the veins of the stomach, of the
small intestines and the cœcum; but it could not be perceived in
the lymph.
_Third experiment._--A dog was made to swallow six ounces of a
solution of Prussiate of Potash in water. In a quarter of an hour,
the urine very evidently contained some of the Prussiate; but the
lymph taken from the thoracic duct showed no appearance of it.
_Fourth experiment._--I gave to a dog, in whom I had tied the
thoracic duct, two ounces of a decoction of nux vomica. The effects
of absorption were as rapid as if the duct had been open. After the
death of the animal I satisfied myself, that the duct had been well
tied, and that there was no other branch, as there sometimes is, by
which the lymph could get to the subclavian vein.
I have varied this experiment by putting the poisonous fluid, into
the rectum, the sacs of the pleura and peritoneum. The results have
been uniformly the same.
_Fifth experiment._--M. Delille and myself made an incision into
the abdominal parietes of a dog, who had been fed very heartily
some hours before, so that the lacteals might be easily seen, and
we then drew out a portion of the small intestine upon which we
applied two ligatures three inches from each other. The lymphatics
that went from this portion of intestine were full of chyle and
very distinct. They were all tied and cut. The blood vessels were
also tied and cut, with the exception of an artery and a vein;
the portion of intestine also was cut off beyond the ligatures,
and thus it had no communication with the rest of the animal
except by the vein and artery which were left. These two vessels
were dissected with the greatest care, and even stripped of their
cellular coat, lest there might be some lymphatics concealed in
it; we then injected into the cavity of this portion of intestine
a decoction of nux vomica, and we retained it there by means of a
new ligature. This portion of intestine, covered with fine linen,
was restored to the abdomen; six minutes after, the effects of the
poison were manifested with their usual intensity.
_Sixth experiment._--M. Delille and myself separated the thigh of a
dog from his body, leaving only the crural artery and vein, which
kept up the communication between the two parts. These two vessels
were dissected with care, insulated to an extent of from two to
three inches, and even stripped of their cellular coat, for fear
it might conceal some small lymphatic vessel. Two grains of a very
active poison (the upas) were then inserted into the paw, and the
effects were as sudden and as intense as if the thigh had not been
separated from the body.
As it might be objected, that notwithstanding all the precautions
taken, the parietes of the artery or vein might still contain
some lymphatic, we varied our experiment so as to leave no doubt
on this point. The artery was cut entirely off, the communication
was reestablished between the two ends, by means of a leaden tube
introduced into their cavity, and fixed by proper ligatures.
The same was done for the vein. Thus there was no longer any
communication between the thigh and the rest of the body, except by
the arterial blood which came to the thigh, and by the venous blood
which returned to the trunk: the poison afterwards introduced into
the paw produced its effects in the ordinary time, that is in about
four minutes.
From these different experiments, it is right to conclude that the
minute branches of the veins possess the power of absorbing; that
they exert it on the surface of the mucous and serous membranes,
and in the interior of the organs; that the experiments that have
been quoted in favour of the absorption of the lymphatics are
inaccurate or incorrectly understood, and finally that there is no
proof that these vessels absorb any thing but chyle.
Is it now necessary to refer to the venous branches this
sensibility that has been attributed to the ultimate ramifications
of the lymphatics? But this sensibility, as we have already said,
would be constantly in error; the absorbent vessel does not select
one fluid in preference to another; all are indiscriminately
absorbed, even the most irritating, those in fact whose action is
sufficiently powerful to destroy the vascular parietes. Besides,
the phenomenon then continues, when it is no longer possible to
suppose the existence of this sensibility. After death even, the
venous branches absorb still as they do during life, if they are
placed in analogous circumstances; and to do this it is evident,
that an internal current must be established, which resembles the
course of the blood. I shall now relate an experiment, which I made
on this subject, and which I selected from many others, because it
appeared to me to be very conclusive.
I took the heart of a dog that had died the day before; I injected
into one of the coronary arteries some water of the temperature
of 30 degrees of the centigrade thermometer. This water returned
easily by the coronary vein to the right auricle, whence it flowed
into a vessel or dish. I poured half an ounce of slightly acid
water into the pericardium. At first the injected water exhibited
no sign of acidity; but in five or six minutes it presented
unequivocal marks of it.
Absorption then can take place without the assistance of this
sensibility, as well as of this insensible organic mobility, which
is supposed to be in the ultimate vascular extremities, in the
absorbing mouths, as they are called. But do these mouths really
exist? Do the last capillary branches terminate abruptly with a
large opening on the surface of the membranes or in the texture of
the organs? Can the absorbed fluids pass through their parietes as
oxygen does in the lungs to arrive at the blood which it modifies?
We are unable to make experiments on these small vessels, that
are not cognizable by our senses; let us make them on the large
ones, and if they permit fluids, in which they are immersed, to
pass through them, for a stronger reason we may suppose that it
takes place in the capillaries, whose parietes are so much more
delicate and consequently more permeable. Now we have confirmed by
experiments what we had suspected; the first attempts were made on
dead vessels.
I took a portion of the external jugular vein of a dog; I stripped
it of the surrounding cellular texture; I attached to each of its
extremities a glass tube by means of which I established a current
of warm water through its interior; I then immersed the vein into a
liquor slightly acid.
It is seen by the arrangement of the apparatus that there could not
be any communication between the internal current of warm water and
the external acid liquor.
During the first minutes the liquid that I collected did not
change its nature; but after five or six minutes the water became
perceptibly acid; absorption had taken place.
The same experiment was repeated on veins taken from human
subjects; the effect was the same; it was the same also with the
arteries, but a little slower from the greater thickness of their
coats.
It remained to be seen if in a living animal absorption thus took
place through the parietes of a large vessel. I know that the
textures that were permeable after death, are almost all so during
life, though the contrary is generally believed. If we inject
into the pleura of a living animal a certain quantity of ink, at
the end of an hour, and often sooner, we shall find the pleura,
the pericardium, the intercostal muscles, and the surface of the
heart itself, evidently of a black colour. It is true that the
signs of this exudation are not always apparent. Thus after death,
the transudation of the gall bladder is rendered evident by the
colouring of the neighbouring parts. During life, on the contrary,
as fast as the colouring particles are deposited, they are absorbed
by the serous membrane which covers the surrounding parts, and
carried off by the sanguineous current which runs through this
membrane and the subjacent organs.
From these considerations we must believe that absorption may take
place through the parietes of the vessel during life as after
death. To be satisfied of this I made the following experiment:
I took a young dog of about six weeks old. At this age the vascular
parietes are delicate, and consequently more likely to render
the experiment successful. I laid bare one of the jugular veins;
I insulated it perfectly in its whole length; I stripped off
carefully every thing which covered it, and especially the cellular
texture and some small vessels that ramified on it; I placed it
on a card, that it might not be in contact with the surrounding
parts; I then let fall, on its surface and opposite the middle of
the card, a thick aqueous solution of an alcoholic extract of nux
vomica, a substance the action of which is very powerful on dogs;
I took care that none of the poison could touch any thing but the
vein and the card, and that the course of blood was free in the
interior of the vessel. Before the fourth minute, the effects that
I expected appeared, at first feeble, but afterwards with so much
power as to render inflation of the lungs necessary to prevent the
death of the animal. I repeated this experiment on an adult animal
of a much larger size than the preceding one; the same effects
appeared but slower, on account of the greater thickness of the
parietes; they began to appear in fact after the tenth minute.
After satisfying myself with this result respecting the veins,
I thought I would ascertain if the arteries exhibited analogous
properties. These vessels are in a less favourable condition;
their texture is less spongy than that of the veins and with an
equal caliber, their parietes are much thicker. It was easy then
to foresee, that if the phenomenon of absorption showed itself, it
would appear much slower than in the veins; this was confirmed in
an experiment on two large rabbits, in whom I dissected perfectly
clean one of the carotid arteries. It was more than a quarter
of an hour before the solution of nux vomica passed through the
parietes of the artery. As soon as I saw the symptoms of poisoning
distinctly, I stopped moistening the vessel; yet one of the rabbits
died. In order then to convince myself that the poison had really
passed through the arterial parietes, and that it had not been
absorbed by small veins which might have escaped my dissection, I
carefully detached the vessel that had been used in the experiment;
I cut it open in its whole extent, and I made those who assisted
me taste a little of the blood, that was still adhering to the
internal surface; they all perceived in it, and I did myself, the
extreme bitterness of the extract of the nux vomica.
To these experiments may be objected a fact that is observed,
which is, that absorption does not take place the same under all
circumstances; its activity is redoubled or diminished, according
to the state of some other functions. Thus during a paroxysm of
fever, a medicine, which would usually act with great effect, often
produces, when given in a double or treble dose, no perceptible
effect. Now if absorption, was a purely mechanical phenomenon,
would it undergo modifications in relation with those of the vital
functions? Without doubt it would; for these modifications of the
functions may introduce new physical circumstances favourable or
injurious to the production of a mechanical phenomenon. Thus in the
present case, the state of fever, by accelerating the circulation
distends with blood the arteries and the veins. The fluid that is
to be absorbed must pass from the exterior to the interior of these
vessels. Now it may be easily conceived, that the quantity of blood
which they contain must have a great influence upon the production
of the phenomenon by the greater or less degree of tension of their
parietes. This is moreover completely confirmed by experiment.
We can, without producing a very great disturbance in the
functions, increase at pleasure the quantity of fluid which passes
through the blood-vessels, by carefully injecting into the veins
water the temperature of which is near that of the blood. An
artificial plethora is thus produced, followed by very curious
phenomena, of which I shall have occasion hereafter to speak. One
day while making this experiment, the idea occurred to me of seeing
what influence the plethora thus produced would exert upon the
phenomenon of absorption.
In consequence, after having injected into the veins of a dog of
middle size about a quart of water, I placed in the pleura a small
dose of a substance, the effects of which were well known to me.
These effects did not show themselves till many minutes after
the period in which they usually appear. I soon made the same
experiment on another animal with the same result.
In many other trials the effects showed themselves at the period in
which they ought to have appeared; but they were evidently weaker
and prolonged much beyond the ordinary time.
Finally, in another experiment in which I had introduced as much
water as the animal could bear and live, the effects did not appear
at all. I waited nearly half an hour for effects which commonly
show themselves in two or three minutes. Presuming then that the
distension of the vessels prevented the absorption, I endeavoured
to satisfy myself of it, by seeing if after the distension had
ceased, absorption would be any longer prevented. In consequence,
I bled the animal copiously from the jugular, and I saw, with the
greatest satisfaction, the effects appearing as the blood flowed
out.
It was proper to make the opposite experiment, that is to say to
diminish the quantity of blood, in order to see if absorption would
take place sooner. This took place in fact, as I thought it would;
about half a pound of blood was taken from an animal; the effects,
which did not usually appear till after the second minute, showed
themselves in thirty seconds.
Yet it might still be suspected, that it was less the distension of
the blood-vessels than the change of the nature of the blood that
opposed absorption. To remove this difficulty I made the following
experiment; a dog was bled copiously; the place of the blood which
he had lost was supplied by water at the temperature of 40 degrees
of the centigrade thermometer, and a certain quantity of a solution
of nux vomica was introduced into the pleura. The consequences of
it were as prompt and as powerful, as if the nature of the blood
had not been changed; it was then to the distension of the vessels
that must be attributed the want or diminution of absorption.
The consequences that may be deduced from the experiments I have
just related will acquire new force, if we connect with these facts
a multitude of pathological ones, which are every day seen; such as
the cure of dropsies, engorgements and inflammations by bleeding;
the evident want of action of medicines at the moment of a violent
fever, when the vascular system is powerfully distended; the
practice of certain physicians who purge and bleed their patients
before administering active medicines to them; the employment of
cinchona at the period of remission for the cure of intermittent
fevers; general or partial oedema from organic disease of the heart
or lungs, and the application of a ligature upon the extremities
after a puncture or a bite of a venomous animal, to prevent the
deleterious effects which are the consequence of it.
On the whole, I think, it may be concluded from the preceding
experiments that the capillary attraction of the small vessels is
one of the principal causes of the absorption called venous. If the
lymphatics do not appear to enjoy in the same manner the faculty of
absorption, it probably arises not from the nature of the parietes,
the physical properties of which are nearly the same as those of
the veins, but from the want of a continuous current in their
interior.
In this note I have brought together the absorption of the gases
and that of fluids. This resemblance holds only as it relates to
the permeability of the textures by these two orders of bodies. As
to the cause of the absorption of the two, it cannot be the same,
since gases are not subjected to capillary attraction.[28]
[28] _Note by the Translator of Magendie’s Additions._--In the
preceding note M. Magendie has not done justice to Mr. Hunter.
Without entering at all into the examination of the question,
whether absorption is performed by the lymphatics or the veins,
it is due to Mr. Hunter to contradict the assertion, that “he
overthrew the ancient theory by _five experiments only_.” He was
not a man who adopted his opinions loosely or on slight grounds,
and in the present case he performed between twenty and thirty
judicious and satisfactory experiments, in the presence of several
physicians and surgeons. It is true that these were performed on
five different animals only, but if the result were uniform, this
number was as good as five thousand or any other one that could be
named.
G. H.
(See Hunter’s Commentaries and Cruikshank on the Absorbents.)
[29] Those theories no doubt are very incomplete that are borrowed
from hydraulics, and probably will be so for a long time; but
it arises from this, that the science on which it is founded,
hydrodynamics, is still but little advanced. A great advance will
unquestionably be made in physiology, when we shall arrive at a
knowledge of the course of a fluid in a system of canals, which
have the same physical conditions as the system of arterial and
venous vessels. But it will be a long time before science will
have arrived at that point. Is it necessary for this to make no
use, in the explanation of the circulation, of the few facts which
are known upon the course of the fluids? Is it necessary to enter
entirely into the field of hypothesis, to suppose in the small
vessels a sensibility and a contractility which evidently do not
exist in the large ones? I cannot believe it, and I think even
that if this hypothesis should be true, and if there should be
demonstrated for the capillary vessels, those properties which are
attributed to them, and which would have an influence on the course
of the blood, we should then know but one of the conditions of this
very complicated problem, and this would not in any degree do away
the necessity of knowing all the mechanical conditions.
[30] Even in reasoning according to the hypothesis of Bichat, and
admitting the existence of this organic sensibility, it would
always be inaccurate to say, that the contraction is uniformly
in proportion to the sensation. How is it to be known in fact?
Since this sensibility is not transmitted to a common centre, it
might very well be excited without our being informed of it by any
apparent effect. Sometimes also a very evident contraction would
correspond to the slightest excitement.
[31] The contractility in the different organs in which we can
observe it does not exhibit characters so striking as those which
Bichat here assigns to it, and the motions which he ranks in
the same class have the greatest differences among them. To be
convinced how little justice there is in this division, it will
be sufficient to trace the progress of the food, along its whole
course, to the interior of the digestive canal. The first act
which is presented to our observation is entirely voluntary; this
is mastication; the act which follows it is not so completely so.
Deglutition in fact can sometimes take place against the will, if a
body of a proper consistence is at the entrance of the pharynx. We
have but an imperfect control over the muscles of the uvula and the
velum palati, if we wish to move these parts separately; we have
perhaps less power still over the contraction of the muscles of the
pharynx, though they do not appear to differ from the locomotive
muscles, either in their symmetry, or in the arrangement and colour
of their fibres, or in the nerves which they receive; nor finally
do they differ in the sudden, instantaneous contraction, wholly
different from the slow contraction, the vermicular motion of the
stomach and intestines.
After having passed the pharynx, the alimentary mass enters the
œsophagus. The motions are there still under the influence of the
nerves; but they are not at all under the influence of the will.
The muscular layer which produces them has not the appearance,
the red colour of the voluntary muscles; but it still preserves
something of the sudden motion of their contraction. Hence we see,
that the motions of the œsophagus cannot be ranked either among the
motions of organic life, since they cease by the division of the
nerves, or among those of animal life, as they are not under the
influence of the will. It is remarkable also that Bichat, who, in
this and the following paragraph, announces the characters of the
different kinds of contractility, does not speak of the œsophagus,
whilst he offers as an example the motions of the bladder, the
heart, the stomach and the intestines.
When Bichat wrote this work, hardly any thing of the motions of
the œsophagus was known, except from the writings of Haller, who
made but four experiments on the subject. I wished to observe them
myself, and I have discovered many facts which I think interesting;
I shall relate them here as I described them in a memoir read to
the Institute in 1813. Before attempting to ascertain what part
the œsophagus took in the passage of the food, it was proper to
ascertain its state when it was supposed to be at rest. In the
first experiments, I noticed an important phenomenon, and which
hitherto had escaped the observation of physiologists, viz., that
the lower third of the œsophagus has constantly an alternate motion
of contraction and relaxation, which appears to be independent of
all foreign irritation. This motion appears to be confined to the
portion of the tube which is surrounded by the plexus of nerves of
the eighth pair, that is to say, to about its lower third; there is
no trace of it in the neck nor in the superior part of the thorax.
The contraction appears like a peristaltic motion, it begins at the
junction of the superior two thirds with the inferior third, and is
continued to the insertion of this tube in the stomach. When the
contraction is once produced, it continues for an uncertain time;
usually it is less than half an hour. The œsophagus contracted
in this way in its lower third is hard like a cord powerfully
stretched. Some persons whom I have made feel of it in this state
have compared it to a rod. When the contraction has lasted the time
I have just mentioned, the relaxation takes place suddenly and
simultaneously in each of the contracted fibres; in some cases,
however, the relaxation seems to take place from the superior
fibres towards the inferior ones. The œsophagus examined during
the state of relaxation exhibits a remarkable flaccidity, which
contrasts wonderfully with the state of contraction.
This alternate motion is dependent on the nerves of the eighth
pair. When these nerves are cut in an animal, this motion entirely
ceases; the œsophagus contracts no more, but it is not in a state
of relaxation; its fibres without the control of nervous influence
shorten; it is this which produces, so far as the touch is
concerned, an intermediate state between contraction and relaxation.
When the stomach is empty or half full of food, the contraction of
the œsophagus recurs at much longer intervals; but if the stomach
be powerfully distended by any cause, the contraction of the
œsophagus is usually very powerful, and continues for a much longer
time. I have seen it, in cases of this kind, continue more than ten
minutes; under the same circumstances, that is to say, when the
stomach is excessively full, the relaxation is always much shorter.
If during the time of contraction, we wished, by mechanical
pressure made on the stomach, to make a part of the aliments which
it contained pass into the œsophagus, it would be necessary, in
order to accomplish it, to employ a very considerable force; and
often even we should not succeed. It seems that pressure increases
the intensity of the contraction, and prolongs its duration. If, on
the contrary, the stomach is pressed during relaxation, it is very
easy to make the substances it contains pass into the cavity of the
œsophagus. If it be a liquid, the slightest pressure, sometimes
even its own weight, or the tendency which the stomach itself has
to contract, will bring about this result. When the stomach is laid
bare and distended above measure, fluid does not usually enter into
the œsophagus, because, as we have said, the distension of the
stomach is a cause which prolongs the contraction of the œsophagus.
The passage of a fluid in the œsophagus is usually followed by its
entrance into the stomach. Sometimes however the fluid is thrown
out. When it goes into the stomach, the œsophagus contracts nearly
the same as in deglutition, sometimes almost immediately after it
has entered it; at other times the œsophagus allows itself to be
considerably distended before it pushes it into the stomach.
It was at the moment of deglutition that Haller observed the
motions of the œsophagus, and the description which he has given
of them is very accurate for the two superior thirds of the canal;
but the action of the inferior third is essentially different;
and this distinction seems to have escaped him. Haller says that
the relaxation of each circular fibre immediately follows the
contraction; and this is true of the portion of the canal situated
in the neck and in the superior part of the thorax; but it is
not accurate for the inferior portion, in which we see that the
contraction of all the circular fibres is continued long after
the entrance of solids or fluids into the stomach. At this moment
the mucous membrane of the cardiac extremity of the œsophagus,
pushed by the contraction of the circular fibres, forms a very
considerable projection into the cavity of the stomach. The
contraction usually coincides with the period of inspiration, when
the stomach is more strongly compressed; the relaxation takes place
most often at the time of expiration. When the aliments have once
entered the stomach, it is this contraction of the inferior part
of the œsophagus which opposes their return. The resistance that
is offered at the other orifice is not of the same species. In
living animals, whether the stomach be empty or full, the pylorus
is uniformly shut by the contraction of its fibrous ring and the
contraction of its circular fibres. There is frequently seen in the
stomach another contraction, at one or two inches distance, which
appears to be designed to prevent the aliments from arriving at the
pylorus. We perceive also irregular contractions, beginning at the
duodenum, and extending to the pyloric portion of the stomach, the
effect of which is to push back the aliments towards the splenic
part.
The aliments remain in the stomach long enough to undergo no other
modifications than those which result from their mixture with the
perspiratory and mucous fluids, which are constantly found in it
and renewed there. During this time the stomach remains uniformly
distended; but afterwards the pyloric portion contracts in its
whole extent, especially in the part nearest the splenic portion,
towards which the aliments are carried. Then there is found, in the
pyloric portion, only the chyle mixed with some unchanged aliments.
When there is accumulated in this part a quantity of it, which is
never very considerable, there is seen, after a moment of rest, a
contraction at the extremity of the duodenum; the pylorus and the
pyloric portion soon take part in this motion, and the chyle is
forced towards the splenic portion; but afterwards the motion is in
an inverse direction. The pyloric portion, which allowed itself to
be distended, contracts from left to right, and directs the chyle
towards the duodenum, which soon passes the pylorus and enters the
intestine. The same phenomenon is repeated a certain number of
times, then it ceases, and commences again after some time. This
motion, when the stomach contains much food, is limited to that
part of the organ nearest the pylorus; but as it becomes empty, the
motion extends, and appears even in the splenic portion when the
stomach is almost entirely evacuated. In general, it becomes more
evident at the end of chylification.
The motion which produces the progression of the chyle in the
small intestines is very analogous to that of the pylorus; it is
irregular, made at variable intervals, it is sometimes in one
direction and sometimes in another, and sometimes appears in many
parts at once; it is always more or less slow, it produces changes
of relations in the intestinal circumvolutions, and it is entirely
beyond the influence of the will.
We should form a very false idea of the motions of the small
intestines during digestion, if we judged of them by those which
these intestines exhibit in an animal recently killed. In this
case, it is not the annular fibres only that enter into action,
so as to exhibit, by their successive contractions, a vermicular
motion. The longitudinal fibres act also in a very conspicuous
manner, and produce a rolling of the intestinal circumvolutions,
which change their relations at every instant. These motions are
never more evident than when the whole mass of intestines is
removed from a living animal.
The motions of the large intestines have nearly the same characters
as those of the small intestines, like these last, they are not
always in the same direction, but push the substances which
are contained in their cavity, sometimes towards the ileum and
sometimes towards the anus. But by means of this motion, these
substances which have already the character of _feces_, can never
re-enter the small intestines. The cause that prevents their
return is different from that which prevents the return into the
stomach of the substances contained in the duodenum. The obstacle
in this case, we have said, is produced by the contraction of
the contractile rings, which are found at the extremity of the
two cavities; in the other, it is produced by a cause purely
mechanical, by the arrangement of the ileo-cecal valve. Hence it
follows, that if the mode of contraction of the different parts
of the intestinal canal be perverted by any cause, it might
happen that their contraction towards the pylorus would not take
place when the duodenum was affected with its anti-peristaltic
motion, and then the substances contained in it, pushed by the
contraction of the annular fibres, would re-enter the stomach. At
the coecum, on the contrary, as the obstacle is purely mechanical,
so long as the ileo-cecal valve is not broken, it will present an
insurmountable obstacle to the return of the _feces_ into the small
intestines.
The motions of the large intestines, sufficient to carry the feces
into the rectum, would not, in a state of health, be powerful
enough to expel them entirely, by overcoming the resistance which
the sphincter constantly presents; in expelling the feces, the
contraction of the intestine is assisted by the pressure which
arises from the lowering of the diaphragm, and by the contraction
of the abdominal muscles.
We have just pointed out the motions which carry the alimentary
mass along the intestines. We may see that they have but little
resemblance among them. The only character that is common to them
is that of not being under the influence of the will. Yet there is
an exception to this in some individuals who possess the faculty
of ruminating. (The will is seen exerting itself on the production
of other _sensible organic motions_. Bayle could stop at will the
pulsation of his heart.) If we examine the motions of the digestive
tube when it is free of aliments, we see their difference in a
manner not less striking. The œsophagus exhibits those alternate
motions that we have described; a very powerful contraction of its
inferior third, and then suddenly the most complete relaxation.
In the stomach we see only some undulations, that go irregularly
from one orifice to another. In the intestines, these motions
exhibit nearly the same regularity, but the groove formed by the
contraction of the annular fibres is deeper, and the undulatory
motion is not so slow. If a stimulating medicine is introduced
into the stomach, these contractions become more evident, and the
motions more rapid; but they always preserve the same character.
The contraction takes place progressively, and never in the sudden
manner of a muscle of locomotion. Of all the substances which can
be used to ascertain these motions, there is no one whose action is
more efficacious than veratrine, a new vegetable alkali extracted
from the _veratrum sabadilla_. If the external parietes of the
digestive tube be excited by any stimulus, by touching it with the
finger, by a puncture, or by the galvanic fluid, there is in the
œsophagus a sudden contraction of the longitudinal and circular
fibres, which narrows the organ and shortens it at the same time;
the relaxation takes place instantaneously and in as striking a
manner. In the stomach, no motion is perceived in the direction of
its length; we see only an annular contraction, which is developed
slowly at the excited point, and which is usually not transmitted
to the neighbouring parts. In the intestines, the excitement
produces a very decided contraction, and very often in the
neighbouring parts a kind of peristaltic motion; but this motion is
always slow and does not at all resemble the sudden contraction of
the œsophagus.
The difference between the motions of the œsophagus and those of
the other parts of the intestinal canal is very remarkable in
birds. In them the œsophagus appears to be entirely membranous; and
yet it contracts like a muscle of locomotion; whilst the stomach,
which has red muscles very similar to the locomotive muscles, has
slow, gradual vermicular motions, like all the canal which is below
it.
There exists finally between the motions of the intestinal canal a
difference relative to the manner in which they terminate. Those
of the intestines, but little sensible during life, acquire at
the moment of death a very great intensity; whilst those of the
œsophagus, before so distinct, cease immediately, and in the most
complete manner.
[32] It is not the dartos that contracts in the motions of the
scrotum, it is the skin itself that produces that vermicular
motion that is observed in this part. This motion can be produced
by stimuli of very different kinds; by the impression of cold, by
pinching the skin or by fear. I have seen these motions so great
in a man on whom I was about to operate for hydrocele, that I was
obliged to wait for a long time for fear of wounding the testicle,
which, by those motions, ascended and descended precipitately.
[33] It might be thought from this expression, that Bichat supposed
that the great arteries influenced the course of the blood by an
active contraction analogous to the muscular contraction; but
this was not his opinion. He only wished to say, that the blood
continued to move in the great arteries solely by the influence of
the heart. This contraction of the great arterial trunks has been
heretofore maintained by many anatomists, and is even at present
by some. There are at the present day three principal theories
relative to the circulation.
In the first, it is contended that all the parts of the arterial
system are irritable, and that they contract like the muscular
texture; many even add that they can dilate spontaneously, as takes
place every instant in the heart. According to this supposition,
the arteries alone would be able to continue the course of the
blood.
In the second opinion, which is that of Harvey, and which is still
adopted, more particularly by the English physiologists, it is
affirmed on the contrary, that the arteries are not contractile
in any point; that if they do contract in certain cases, it is in
virtue of that property common to all the solids, by which they
return upon themselves, when the cause that has distended them
ceases to act. The partisans of this opinion conclude that the
arteries have not and cannot have any influence upon the motion
of the blood which runs through them, and that the heart is the
principal, and as it were, the sole agent of the circulation.
Finally the third opinion, that which now prevails most generally
in France, consists in a union of the two preceding ones; the
trunks and principal arterial branches are considered as incapable
of acting upon the blood; but this property is attributed to the
small arteries, and it is thought to be very great in the last
divisions of these vessels. Thus, in this mixed opinion, the blood
is carried by the sole influence of the heart in all the arteries
of a considerable size; it is moved in part by the influence of the
heart and in part by that of the parietes in the smaller arteries,
and finally it is moved by the sole action of the parietes in the
last arterial divisions. This action of the small vessels is also
described as the principal cause of the course of the blood in the
veins.
In a question of this nature our opinion should be determined by
experiments alone. This presents many points for elucidation.
The first and the easiest to be decided is to ascertain if the
arteries are or are not irritable. The problem was in some measure
resolved in relation to the great arteries by the experiments of
Haller and his disciples, by Bichat himself, and by those which M.
Nysten has made upon man. For the purpose of being more perfectly
convinced, I have sought, by all the known means, to develop
the irritability of the arterial parietes; I have successively
subjected them to the action of pricking instruments, of caustics
and of galvanism, and I have never perceived any thing which
resembled a phenomenon of irritability; and as those who maintain
the irritability of the arteries pretend that if we do not perceive
the contractions, it is because the experiments are made on too
small animals, in whom the effects are but slightly apparent in
consequence of the small diameter of these canals, I have repeated
the experiment on large animals, on horses and asses, and I have
never observed any other motions than the communicated motions.
As the great arteries show no contraction, we ought to believe
that the small ones would not; but as among the physiologists who
reject the irritability of the arterial trunks, some like Haller,
do not speak of the branches, others accord to them contractility,
it becomes necessary to test this question by experiment; now these
small vessels, like the larger ones, remain perfectly immoveable
under the action of the scalpel, caustics and a stream of galvanic
fluid.
Irritability does not exist then in the large or the small
arteries. Respecting the last arterial divisions, as the vessels
which form them are so small that they cannot come under the
cognizance of the senses, at least in a state of health, no one can
affirm or deny that they are irritable. Yet from analogy we ought
to conclude, that they have no sensible motion. In cold-blooded
animals, in fact, it is easy to see the blood circulating in
these vessels, and even passing into the veins; now the vessels
themselves appear to be completely immoveable.
As the arteries cannot act upon the blood by contracting in the
manner of muscles, must we conclude that they have no action
upon this fluid, and that they are in relation to it nearly like
inflexible canals? I am very far from thinking so. If in fact the
arteries had no influence upon the blood, this fluid, moved by
the sole impulse of the heart, would, from its incompressibility,
be alternately in motion and at rest. This is indeed what Bichat
thought, and what he has advanced in his other works; it is what
has been since maintained in a more formal manner by Dr. Johnson
of London. It is however very easy to prove that it is not in this
way that the blood is moved in these vessels. Open a large artery
in a living animal, and the blood will escape in a continuous jet,
but by jerks; open a small artery, and the blood will flow out in
a continuous and uniform jet. The same phenomena take place in
man if the arteries are opened, either by accident or in surgical
operations. The heart being unable to produce a continuous flow,
since its action is intermittent, it must be then that the arteries
act upon the blood; this action can only be the disposition
which they have to contract, and even to obliterate their cavity
entirely. Bichat thought that his tendency to narrowing was not
sufficient in the arteries to expel the blood contained in their
cavity. He maintains that the vessel does not contract upon itself
only when the blood has ceased to distend it. If it were so, the
arteries would be equivalent to inflexible canals, and the course
of the arterial blood would not be continuous; but we can easily
demonstrate that the force with which the arteries contract is more
than sufficient to drive out the blood that they contain.
When two ligatures are applied at the same time and at some
centimetres distant upon two points of an artery which furnishes
no branches, we have a portion of artery in which the blood is
subjected only to the influence of the parietes. If we make in
this portion of the vessel a small opening, almost all the blood
that it contains is immediately thrown out, and the artery is much
contracted. This experiment has been known for a long time, and
uniformly succeeds. The following is one of my own, and places,
it seems to me, the phenomenon in a very clear light. I laid bare
the crural artery and vein of a dog to a certain extent; I passed
under these vessels, near the trunk, a string, which I afterwards
drew tightly at the posterior part of the thigh, so that all the
arterial blood should come to the limb by the crural artery, and
all the venous blood return to the trunk by the crural vein; I then
applied a ligature upon the artery, and this vessel was very soon
completely empty in the part below the ligature.
It is then satisfactorily proved that the force with which the
arteries contract upon themselves is sufficient to expel the blood
they contain. But what is the nature of this contraction? We have
proved that it cannot be attributed to irritability. Every thing
leads to the belief that it should be referred to the very great
elasticity which the arterial parietes enjoy, an elasticity that
is brought into action, when the heart forces a certain quantity
of blood into the cavity of these vessels. This property of the
arteries being known, it is easy to conceive how the principal
agent of the arterial motion, being alternate, the course of fluid
is yet continuous. The elasticity of the arterial parietes is
similar to that of the reservoir of air in certain pumps with an
alternate action, and which notwithstanding throw out the fluid in
a continuous manner.
It is not enough to know the kind of influence which the
contraction of the arteries has on the motion of the arterial
blood; it is necessary to know if this contraction does not
influence in a sensible manner the course of the blood in the
veins. This is elucidated by the following experiment. Lay bare,
as in the preceding experiment, the crural artery and vein of
a dog; tie the limb strongly, taking care not to include these
vessels; afterwards tie the crural vein, and make a small opening
in it below the ligature, of one or two lines in length; the blood
flows out in a continuous jet. If the artery be compressed, so as
to intercept the course of blood in it, the jet still continues
a short time; but it is seen sensibly to diminish, as the artery
is becoming empty. It at length ceases entirely when the artery
is completely emptied; and though the vein remains distended
with blood along its whole extent, it does not flow out at the
small wound. If the compression be taken off of the artery, the
blood enters it with force, and almost at the same instant it
begins again to flow from the opening in the vein, and the jet is
reestablished as before. If we check the course of the blood in the
artery, there is but a feeble jet from the vein; it is the same if
the passage of this fluid is alternately intercepted and permitted.
I make the same phenomenon evident in another way; I introduce into
the crural artery the extremity of a syringe filled with water at
the temperature of 30 degrees of the centigrade thermometer; I push
the piston slowly, and soon the blood goes out by the opening in
the vein, at first alone and afterwards mixed with water, and it
forms a jet the more considerable in proportion to the force with
which the piston is pushed.
To prove, as we have done, that the heart maintains an evident
influence on the course of the blood in the capillary vessels, is
not to advance that these vessels have no action on the motion of
this fluid. Many physiological phenomena, on the contrary, prove
that the capillaries can aid with more or less facility the passage
of the blood, and consequently sensibly influence its course.
[34] Under no circumstance does the stomach rise up, as Bichat
calls it. We have, in a preceding note, explained the ordinary
motions of this viscus, in a state of vacuity, during digestion and
under the influence of an internal or external stimulus. None of
these motions are sufficient to produce that sudden and energetic
expulsion which characterizes vomiting. The opinion that the
stomach rises up in vomiting originated in a time of ignorance,
and we ought not to be astonished that it should find advocates
even in our day. This has not however been uniformly adopted; Bayle
and P. Chirac opposed it by experiments; Senac, Van Swieten and
Duverney declared themselves against it; but Haller, by adopting
it, suddenly changed the views and removed the uncertainty of a
great number of physiologists, who, not taking the labour of making
experiments for themselves, loved to repose on the faith of a
celebrated name. In physiology the opinions of Haller are certainly
entitled to very great weight; this is because this wise observer,
before announcing them as a general proposition, was accustomed to
repeat many times the experiments on which he founded them; but in
this case he did not sufficiently question the use of the stomach
in vomiting.
He has made four experiments only, less for the purpose of
satisfying himself that the phenomenon existed, than to see it such
as he supposed it. It is very difficult, even for the best mind,
to divest itself in observing, of the ideas previously received
without examination. It may then be believed, that Haller in this
way saw but superficially. These considerations determined me some
years since, to satisfy myself of what takes place in vomiting,
and of the part which the stomach performs in it. I shall relate
briefly the experiments which I tried on the subject. The first
was made on a dog of middling size, whom I had made to swallow six
grains of emetic. When this medicine had excited nausea, I cut
through the linea alba opposite the stomach, and introduced my
finger into the abdomen. At each nausea, I felt it very powerfully
compressed above by the liver, which the diaphragm pushed down, and
below by the intestines, which were compressed by the abdominal
muscles. The stomach also appeared to me to be compressed; but
instead of feeling it contract, it appeared to me, on the contrary,
to increase in size. The nauseas became more frequent, and the more
marked efforts, which precede vomiting, appeared. Vomiting finally
took place, and then I felt my finger pressed with a force truly
extraordinary. The stomach rid itself of a part of the aliments it
contained; but I distinguished no sensible contraction in it. The
nausea having ceased for a short time, I enlarged the opening in
the linea alba, for the purpose of observing the stomach. As soon
as the incision was enlarged, the stomach presented itself at it,
and made an effort to come out of the abdomen; but I prevented it
with my hand. The nauseas returned in a few minutes, and I was
not a little surprized to see the stomach filled with air, as
they came on. In a very little time the organ had become three
times its former size; vomiting soon followed this dilatation,
and it was evident to all who were present, that the stomach had
been compressed without having experienced the least contraction
in its fibres. This organ rid itself of air and of a portion of
aliments; but, immediately after the exit of these substances, it
was flaccid, and it was not till after some minutes, that gradually
contracting, it became nearly of the same dimensions as it was
before the vomiting. A third vomiting took place, and we saw again
the same series of phenomena.
For the purpose of ascertaining whence the air came, which, during
the nauseas, distended the stomach, I applied a ligature on the
stomach near the pylorus, so as to close the communication which
exists between this organ and the small intestines, and I made the
dog swallow six grains more of emetic in powder. At the end of half
an hour the vomiting returned, accompanied by the same phenomena.
The distension of the stomach by air was at least as marked as
in the preceding experiment; besides there was no appearance
of contraction of the stomach, and we could not even clearly
distinguish its peristaltic motion. The animal having been killed
some moments after, in an experiment which had no relation to
vomiting, we examined the abdomen. We saw that the stomach was of
considerable size; its texture was flaccid and not all contracted;
the ligature, at the pylorus, was not displaced, and the air had
not been able to pass this way.
Having repeated this experiment and uniformly obtained the same
results, I thought it right to conclude with Chirac and Duverney,
that the mechanical pressure, exerted on the stomach by the
diaphragm and the abdominal muscles, is much concerned in the
production of vomiting; now, if it were so, by removing this
pressure from the stomach, vomiting would be prevented; experiment
confirmed this conjecture.
I injected into the vein of a dog four grains of an emetic
dissolved in two ounces of common water, (in this way vomiting is
produced quicker and more certainly;) I afterwards made an opening
in the abdomen, and when the first efforts of vomiting began, I
quickly drew out the whole of the stomach, which did not prevent
the efforts of vomiting from continuing. The animal made precisely
the same efforts as if he had vomited; but nothing came from the
stomach; this organ remained completely immoveable. I wished then
to see what would be the effect of pressure made on the stomach;
for this purpose, I placed my right hand on the anterior face of
this organ, and my left hand on the posterior face. The pressure
was hardly commenced when the efforts of vomiting, that is to
say, the contraction of the diaphragm and the abdominal muscles
powerfully recommenced. I suspended the pressure; the abdominal
muscles and diaphragm soon suspended their contractions. I renewed
the pressure; the contractions of the muscles began again; then I
suspended it; they ceased; and seven or eight times in succession.
The last time, I made a strong and continued pressure; this
produced a real vomiting. A part of the substances contained in
the stomach was thrown off. I repeated this experiment on another
dog; I observed the same facts; only I remarked moreover that the
contractions of the diaphragm and the abdominal muscles can be
produced by merely drawing by the œsophagus.
In the experiment just related, the emetic substance was introduced
into the veins, and we have already remarked, that the effects
were quicker and more certain than if the same substance had been
introduced into the stomach. This alone should make us suspect that
vomiting is not owing, as is generally believed, to the impression
of the emetic on the mucous membrane of the stomach; for, in this
case, its action ought to have been more prompt when it was placed
directly in contact with this membrane, than when it arrived at it
with the blood after having passed through the lungs and the four
cavities of the heart. For the purpose of elucidating this question
and of seeing if the contractions of the muscles were the result
of the impression produced on the stomach, or if they were excited
more directly by the emetic substance mixed with the blood, I made
the following experiment:
I opened the abdomen of a dog, and having brought the stomach out
at the opening, I tied with care the vessels that went to this
viscus, and I removed the whole of it (I ascertained in some of
the preceding experiments that a dog can live eight and forty
hours after his stomach has been removed.) I made a suture in
the abdominal parietes; then, having laid bare the crural vein,
I injected into its cavity a solution of two grains of emetic in
an ounce and a half of water. I had hardly finished the injection
when the dog began to have nausea, and he soon made all the efforts
that an animal does when he vomits. These efforts appeared to me
to be even more violent and longer continued than in ordinary
vomiting. The dog remained quiet about a quarter of an hour; I
then renewed the injection, and I forced two grains more of emetic
into the crural vein; this was followed with the same efforts of
vomiting. I repeated the experiment many times and always with
the same success; but this experiment suggested to me another,
which I performed in the following way: I took a dog of good size,
from whom I removed the stomach, as I had done in the preceding
experiment; I introduced into the abdomen a hog’s bladder, to the
neck of which I had fixed, by threads, a canula of gum elastic; I
put the end of this canula into the extremity of the œsophagus, and
I fixed it there also by threads, so that the bladder resembled
somewhat the stomach, and was, like it, in communication with the
œsophagus. I introduced into the bladder about a pint of common
water; this distended it, but did not fill it completely. A suture
was made in the wound of the abdomen, and four grains of emetic
were injected into the jugular vein. Nausea soon appeared, and
was followed with real efforts of vomiting; finally, after some
minutes, the animal vomited up abundantly the water from the
bladder.
It followed evidently from the preceding experiments, that the
abdominal muscles and the diaphragm concurred to produce vomiting;
but it remained to be ascertained, what was the part of the
diaphragm in the production of this phenomenon, and what was that
of the abdominal muscles.
If the diaphragm received only diaphragmatic nerves, it would be
easy to resist the contraction of this muscle by dividing these
nerves; but it also receives filaments from dorsal pairs, and
these filaments are sufficient to support its contractions. Yet
experiment shows us, that the diaphragmatic nerves being cut, the
contraction of the diaphragm is very evidently diminished in power,
and it may be said, without much hazard of mistake, that this
muscle loses, by this division, three quarters of its contractile
force. It was then useful to see what influence the division of
these nerves would have on the production of this phenomenon. I
made this division in the neck of a dog of three years old, and I
afterwards injected into the jugular vein three grains of emetic;
there was only a very feeble vomiting; another injection of emetic,
a quarter of an hour after, excited no vomiting. I opened the
abdomen and endeavoured to produce vomiting by compressing the
stomach. The compression, though very powerful and long continued,
excited no effort of vomiting; it did not even appear to produce
nausea. I thought that this circumstance might be owing to the
idiosyncrasy of the animal; but having many times since repeated
this experiment, I have never obtained any other result.
In order to understand what part the abdominal muscles by their
contractions take in vomiting, we ought to observe what takes
place when these muscles are unable to act. There is but one way
of coming at this, which is, to separate these muscles from their
attachments at the sides of the linea alba; this we have done on
many animals; we have detached successively the external oblique,
the internal oblique and the transversalis, leaving on the anterior
face of the abdomen only the peritoneum. When these muscles are
thus removed, we can see very distinctly through the peritoneum,
all that takes place in this cavity; we distinguish, for example,
perfectly the peristaltic motion of the stomach and the intestines;
and if the stomach contracts it will be easy to see it. The
abdominal muscles being thus detached, I injected three grains
of emetic into the jugular vein, and also immediately nausea and
vomiting took place by the contraction of the diaphragm alone. It
was curious to see, in the convulsive contraction of this muscle,
the whole intestinal mass pushed downwards, and pressing strongly
against the peritoneum, which was ruptured in some places. In this
case, the linea alba, formed by a very strong fibrous texture,
is the only part which resists the pressure of the viscera; its
existence then is indispensable to the action of vomiting; perhaps
it performs an analogous office in the ordinary state. This
experiment proves that vomiting can be produced by the efforts
of the diaphragm alone; this is also confirmed by the following
experiment:
I detached, as above, the abdominal muscles and laid bare the
peritoneum; I afterwards divided the diaphragmatic nerves, and
injected an emetic into the veins. The animal had some nausea, but
nothing more. Though I repeated many times the injection of the
emetic, I never was able to produce any sensible effort of vomiting.
From the different experiments that we have just related, and from
the facts that we made known in a preceding note relative to the
motions of the œsophagus, we may conclude, without any hazard,
1st. That vomiting can take place without any contraction of the
stomach.
2d. That the pressure exerted immediately on the stomach by the
diaphragm and abdominal muscles, appears to be sufficient to
produce vomiting, when the occlusion of the inferior part of the
œsophagus offers no obstacle to it.
3d. That the convulsive contraction of the diaphragm and abdominal
muscles, in vomiting from tartarized antimony and emetic substances
properly so called, is the result of a direct action of these
substances on the nervous system and independent of the impression
felt by the stomach.
[35] The motions of the iris cannot be attributed to an active
expansion of an erectile texture; they are owing to the
contractions of two muscular layers, one of which is radiated and
enlarges the opening of the pupil, the other is orbicular and
contracts it.
The motions of the iris, like all those which have muscular
contraction for their cause, can be excited for a considerable time
after death by the galvanic fluid. During life, the motions of the
pupil are produced in man, by the more or less vivid impression of
light on the retina. But they are beyond the influence of the will;
in birds on the contrary, they appear to be entirely subjected
to it. In these animals, we can even after death, and on an eye
entirely detached from the body, produce the motions of the iris by
pricking the optic nerve.
[36] When a patient dies after having for a long time been
deprived of solid and liquid nourishment, it is not rare to find
in him the stomach and intestines considerably lessened in their
two dimensions, the internal cavity almost entirely effaced, the
length being hardly a third of what it was before the disease.
We truly say then with Bichat that is a contraction from a want
of extension. But that this mode of contractility is as he says
perfectly independent of life and owing only to the arrangement
of parts, is what cannot be admitted. If it were so in fact, by
emptying the stomach after death, we might produce a contraction
similar to that which is produced during life. Now experiment shows
us, that this does not take place. The stomach when emptied remains
flaccid, and does not contract in any perceptible degree.
[37] We know that the organs are nourished, that the glands
secrete, we know that certain vessels absorb (whether they be
the lymphatics or not,) but we do not know, that all this is
produced by a _partial oscillatory movement in each fibre, in each
molecule_. No one can be certain that this movement takes place,
because no one has seen it.
[38] Why invent a new word, when we have that of elasticity,
which expresses for all bodies whether organic or inorganic, that
tendency to resume their usual form and size, when the cause that
made them change them is no longer in exercise?
[39] Bichat here unites three sorts of motion which have no
relation between them; the systole of the cavities of the heart
should be considered as a really active dilatation. The increase of
size of the corpora cavernosa, which is an effect purely passive of
the accumulation of blood in those parts, and which can be produced
after death by artificially accelerating the circulation in them;
and finally, the motion of the iris, a motion evidently produced
by a muscular contraction, excitable by galvanism or pricking the
nerve.
[40] Without denying the influence which the capillary systems of
the different organs have on the circulation, we have shown that
even in the veins the action of the heart is felt and modifies the
course of the blood.
CHAPTER VIII.
OF THE ORIGIN AND DEVELOPMENT OF THE ANIMAL LIFE.
If there be any circumstance, which establishes a real line of
demarcation between the two lives, this circumstance undoubtedly
is the mode and epoch of their origin. The organic life is active
from the very first moment of our existence; the animal life begins
after birth only; for without external excitants the latter is as
necessarily condemned to inaction, as without the fluids of the
œconomy, which are its internal excitants, the former would become
extinct. But the subject, on which we are now engaged deserves a
more particular discussion, and in the first place let us examine,
in what manner the animal life, which for some time is absolutely
null, is born as it were and developed.
I. _In the fœtus the first order of the functions of the animal
life is not as yet in action._
The instant, at which the fœtus begins to exist, is nearly that of
its conception; but this existence, the sphere of which is every
day enlarged, is not the same as that, which the child is destined
to enjoy after birth.
The state, in which the fœtus exists while in the womb, has been
compared to that of a profound sleep. Such comparison is inexact.
In a state of sleep the animal life is only in part suspended. In
the fœtus it has not commenced. We have seen in fact, that this
life is made up of the simultaneous or distinct exercise of the
senses, of the nerves, of the brain, of the organs of locomotion,
and the voice. Now in these different functions every thing in such
state is inactive.
Every sensation supposes the action of external bodies upon our
own, together with the perception of such action; a perception
which takes place by virtue of the sensibility of the system, which
is either general or particular, for the tact is the faculty of
perceiving general impressions, and has for its object to warn us
of the presence of bodies, together with their common attributes,
such as heat, cold, dryness, or humidity, hardness or softness. To
perceive the particular modifications of bodies is the business of
the senses.
Has the fœtus in utero any general sensations? To decide this
question, let us enquire whether any impressions are capable there
of exercising its tact. The fœtus lives in a temperature at all
times the same, swims in a fluid, and is thrown from time to time
against the parietes of the womb: such are the three sources of its
general sensations.
We shall now remark, that the two former are next to nothing,
and that the fœtus cannot have a consciousness of the medium, in
which it is nourished, nor of the heat, by which it is penetrated,
for every sensation supposes a comparison between an actual and
a past state of being. We are sensible of cold, only because we
have experienced an antecedent heat; were the temperature of
the atmosphere invariable, we should have no idea whatever of
temperature. The Laplander enjoys himself in a climate, which
would be pain, and death to the Negro, if suddenly transported
thither. It is not at the time of the solstices, but at that of
the equinoxes, that our sensations of heat, and cold are the most
lively. The reason of which must be, that at the latter seasons,
their varieties are more numerous, and occasion more frequent
comparisons between that, which we feel and that which we have felt.
What we have now said of temperature, we may repeat with respect
to the waters of the amnios: the fœtus cannot be sensible of their
influence, because the contact of any other medium is unknown to
it. Before bathing, we are not sensible of the air, after bathing,
the impression made by it upon us is unpleasant. It then affects
us because there has been an interruption of its action upon the
cutaneous organ.
Is the shock of the parietes of the matrix a more real cause of
excitement, than the waters of the amnios, or temperature? At first
we might be inclined to answer this question in the affirmative,
because the fœtus being only at intervals subject to such stimulus,
there should appear to result from thence a sensation. But let us
remark that the density[41] of the uterus in a state of pregnancy
being little greater than that of its waters, the impression must
be trifling. In fact the more the consistence of bodies resembles
that of the medium in which we live, the less powerful will be
their action upon us. Water for instance, when reduced into vapour
in our common fogs, and mists, affects the tact but slightly;
in proportion as it is condensed it is the cause of a livelier
affection.
The air then, to the animal which breathes, is truly the general
comparative term, to which he refers all the sensations of tact. If
the hand be plunged into carbonic acid gas, such substance will not
affect the tact because its density is little different from that
of the air.
The variety then of these sensations is in proportion to the
difference existing between the density of the air, and that of
the bodies, which are the occasion of such sensations. In the same
way, the measure of the sensation of the fœtus must be the excess
of density in the matrix above that of its waters. Now such excess
being very inconsiderable, the sensation of it must be very obtuse.
This assertion with respect to the fœtus will become more general
if we add to it the following: namely, that the mucous membranes,
which are the seat of an inward tact have not as yet begun to
exercise their functions. These membranes, after birth, being
continually in contact with extraneous substances, possess in these
bodies so many causes of irritation, which being continually
repeated, become excitants to the organs: but in the fœtus there is
no succession in these causes. The same urine, the same meconium,
the same mucus at all times exercise their action upon the bladder,
the intestines, and pituitary membrane.
From all this we may conclude, that the general sensations of the
fœtus are very inconsiderable, though it should appear that the
child in this state is surrounded by many of the causes, which
are hereafter to beget sensations. Neither are the particular
sensations of the fœtus more active; indeed they cannot be so for
their causes are absent.
The eye which is closed by the pupillary membrane, and the
nostrils, which are scarcely indicated, would not be capable of
receiving impressions, even in the supposition that light and
odour could act upon them. Applied against the palate, the tongue
is in contact with nothing capable of producing savour. Were it
in contact with the waters of the amnios, the effect would be the
same, because as we have said, there is no sensation, where there
is no variety of impression. The saliva of one person to another
person possesses savour, to the individual himself it is insipid.
The ear in like manner is awakened by no sound. All is calm, every
thing reposes with the little individual.
Here then we have proved, that four of the gates of sensation are
shut in the fœtus; and let us now observe that the nullity of
action in the senses which we have mentioned, must occasion very
nearly the same nullity with respect to that of the touch.[42]
In fact, this sense is especially destined to confirm the notions
which are acquired by the others, and to rectify them, for the
latter are frequently illusory--the touch is always the agent
of truth.[43] In attributing to the touch such use, nature has
submitted it directly to the will; light, odours, and sounds affect
their respective organs independently of the will.
The exercise of the other senses precedes that of the touch, they
are the occasion of it. If a man were born without sight, hearing,
smell, or taste, can we conceive in what way, he would be possessed
of the sense of touch?
The fœtus resembles such a man; it possesses wherewithal to
exercise the touch in its hands, which are already developed, and
in the parietes of the matrix. Nevertheless the fœtus is never in
action, because in seeing, in hearing, in smelling, and in tasting
nothing, it is not disposed to exercise the touch in any way. Its
members are little better than what to the tree are its branches,
which do not transmit the impression of the bodies, with which they
are entangled.
I shall here notice a great difference between the tact and
the touch; they were formerly confounded by physiologists; the
impressions of the latter are always directed by the will, those of
the former do not depend on it. We shall conclude that the portion
of the animal life which constitutes sensation, does not exist in
the fœtus.
This nullity of action in the senses supposes the same deficiency
of action in the nerves, which belong to them, and in that of the
brain from whence they issue; for the business of the former is
to transmit, of the latter to receive. Now without objects for
transmission and reception, the two functions cannot have place.
From perception are immediately derived the memory and imagination;
from these the powers of the judgment and the will. All this series
of faculties then has not had a beginning in the fœtus, because
the fœtus has not perceived, or had sensation. The brain exists
in a state of expectation, it possesses all that is requisite for
action. It does not want excitability, but stimulus. The first
division of the animal life in consequence, or that, which relates
to the action of exterior bodies, on the animal, has scarcely an
outline in the fœtus. Let us examine whether the same be true of
the second division of the animal life, or that which relates to
the reaction of the living body.
II. _Locomotion exists, but belongs in the fœtus to the organic
life._
When we see the strict connexion which exists in animals, between
sensation and their voluntary efforts, we might be induced to
believe, that voluntary motion increases or diminishes with the
increase or diminution of sentiment; for as sentiment furnishes out
the materials of the will, when it does not exist, volition cannot
exist: from induction to induction, it might thus be proved that in
the fœtus the muscles must be totally inactive.
Nevertheless the fœtus moves, and sometimes even very strong
shocks are the result of its motions. The reason why it does not
produce sound, is because the medium for the production of sound is
wanting. But how can we ally the inertia of the first part of the
animal life with the activity of the second. It is thus.
We have seen in speaking of the passions, that the muscles of
locomotion are brought into action in two manners. 1st, by the
will; 2dly, by sympathy. This last mode of action occurs, when from
the affection of an inward organ the brain is affected also, and
occasions a motion which, in such case, is involuntary. A passion,
for instance, affects the liver, the liver the brain, the brain the
voluntary muscles. Here it is the liver, not the brain, which is
the principle of motion: so that the muscles, though always thrown
into action, immediately from the irradiations of the brain, belong
nevertheless, as to their functions, sometimes to the one life,
sometimes to the other.
Hence it is easy to conceive in what way the fœtus moves: with the
fœtus, locomotion is not a portion of the animal life; its exercise
does not suppose a pre-existent will; it is purely a sympathetic
effect.
In utero the phenomena of the organic life succeed each other with
an extreme rapidity; a thousand different motions are incessantly
connected in the organs of circulation and nutrition. In these,
every thing is energetically in action. But this activity of the
organic life supposes a frequent influence exerted upon the brain
by the inward organs, and consequently as many reactions on the
part of the brain by sympathy upon the muscles. Besides, the brain
is at such time more susceptible of such sort of influence, being
much more developed than the other organs, and entirely passive on
the side of the sensations.
We may now conceive what the motions or the fœtus are. They belong
to the same class as many of those of the adult, which have not
been as yet sufficiently distinguished. They are the same as those
which are produced in the voluntary muscles by the passions;
they resemble those of the man who sleeps, and who moves without
dreaming, for nothing is more common than violent agitation in
sleep succeeding difficult digestion. The stomach is in strong
action; it acts upon the brain; the brain upon the muscles.
I might find a number of other involuntary organic motions taking
place in the voluntary muscles of the adult, and consequently
adducible to my present purpose; but what I have said on this
subject will suffice. Let us remark only, that the organic motions,
as well as the sympathetic affection of the brain, which is the
seat of them, must gradually dispose this organ, and the muscles of
the fœtus, the one to the perception of sensations, and the other
to the motions of the animal life, which are to commence after
birth. But on this head I shall refer to the memoirs of Monsieur
Cabanis.
From what has been said, then, I believe we may confidently assert,
that in the fœtus the animal life does not exist, and that all
the actions which take place at this age, depend upon the organic
life. The fœtus, indeed, has nothing of the especial character of
the animal. Its very existence is that of the vegetable; and its
destruction can only be said to be that of a living body, not of
an animated being. Thus, in the cruel alternative of sacrificing
the life of the mother, or that of the child, the choice cannot be
doubtful.
The crime of destroying a fellow-creature is much more relative
to his animal, than to his organic life.--We regret the being who
feels, who reflects, who wills, who acts accordingly, and not the
being which breathes, which is nourished, which is the seat of the
circulation and the secretions. It is the former, whose violent
death is accompanied with those images of horror, under which we
look on homicide. In proportion then as in the series of animals,
their intellectual functions diminish, is diminished also the
painful sentiment which we feel at sight of their destruction.
If the blow, which terminates by an assassination the life of a
man, were to destroy his organic life only, and suffer the other
to subsist without alteration, such blow would be regarded with
indifference, would excite neither pity for the victim, nor horror
against the aggressor.
III. _Development of the animal life, education of its organs._
A new mode of existence commences for the infant after birth; a
variety of functions are added to its organic life; their aggregate
become more complicated; their results are multiplied. As for
the animal life, it only begins; and at this period a number of
relations are established between the little individual and what
surrounds him. It is then that every thing assumes with him a
different mode of being, but at this remarkable epoch of the two
lives, where the one is augmented by almost the half, and where
the other commences only, they take upon them both a distinct
character, and the aggrandisement of the first by no means follows
the same laws as the development of the second.
We shall soon remark, that the organs of the internal life attain
at once their perfection, and that from the instant at which they
begin to act, they act with as much precision as they ever will
do. On the contrary, the organs of the external life require a
species of education; they arrive only by degrees at the perfection
which we afterwards see in them. This important difference should
be thoroughly examined. Let us begin by appreciating of what the
animal life at first consists.
In examining the different functions of this life, which start at
once into existence, we shall observe in their development a slow
and graduated progress.--We shall see, that it is insensibly and
by means of a real education that the organs attain a precision of
action.
The sensations are at first confused; they transmit only general
images; the eye has only the sensation of light; the ear that of
sound only; the nose only that of smell. As yet there is nothing
distinct in these general affections of the senses; but from habit
the strength of the first impression is lessened and the particular
sensations take place. The great differences of colours, sounds,
smells, and savours, become perceptible; by little and little their
secondary differences also are perceived, and after a certain lapse
of time the child has learnt to see, to hear, to smell, to taste,
and to touch.
After successfully undergoing the operation for the cataract, the
patient, who has previously been totally blind, is sensible of
light only, and learns by gradation to distinguish the objects
which reflect it. Another person, before whom, as I have said, for
the first time is exhibited the magnificent spectacle of an opera,
at the first glance, perceives only a whole, which delights him,
and only by degrees is able to isolate the enjoyments of which the
dance, the music, and the decorations are productive.
The education of the brain is similar to that of the senses.
Whatever depends upon its action, acquires the perfection, to which
it is destined, by degrees only. The powers of perception, memory
and imagination, which are all of them preceded and occasioned by
the sensations, increase and extend in proportion as by repeated
excitement they are brought into exercise.--The judgment, of which
they form the triple base, associates but irregularly at first its
motions, which themselves are but irregular. In a short time a
greater degree of perspicuity is observed in its operations, and
lastly they become precise and rigorous.
The voice and the agents of locomotion exemplify the same
phenomenon: the cries of young animals at first are only an
unformed sound, which possesses no sort of character: by age they
are gradually modified, and after long repeated exercise affect the
peculiar consonances of the species, by which, and particularly
during the season of their loves, the individual of the same
species is never deceived.[44] I do not instance the speech of man,
for this is evidently the fruit of education.
In examining the newly born animal, its muscles will be seen
continually in action. As every thing is new to it, every thing
is an excitant to it, and makes it move; it endeavours to touch
every thing, but neither progression, nor the power of standing
can have place when the contractions of the voluntary muscles
are so numerous. It is necessary for such, that habit shall have
taught it to combine particular contractions with other particular
contractions; until then it stumbles and falls at every moment.
Undoubtedly the inclination of the pelvis in the fœtus, the
disposition of the femora, and the want of curvature in the spine,
adapt it but little for standing immediately after birth; but with
these causes is certainly also combined the want of exercise.[45]
Who does not know, that if a limb be suffered to remain immoveable
for a length of time, it loses the habit of moving, and that when
afterwards its service is required, it requires a new kind of
education before it can exercise its movements with any regularity
or precision. The man, who for a long time should condemn himself
to silence, would experience in like manner the same embarrassment
in his first attempt at utterance.
From these considerations we may conclude that our exterior life,
to allow myself the expression, is learnt, and requires before it
can be perfected, a sort of apprenticeship.
IV. _Of the influence of society over the education of the organs
of the animal life._
Over this sort of education, which the organs of the animal life
receive, society exercises a very great influence; it enlarges
the sphere of action of some of them, lessens it for others, and
modifies it in them all.
I shall first remark, that it constantly gives to some of the
organs a perfection greater than naturally should be their
portion. Such in fact is the nature of our occupations as always
to require the especial action of some one, or other of these
organs. The ear of the musician, the palate of the cook, the brain
of the philosopher, the muscles of the dancer, and the larynx of
the singer, receive in addition to the general education of the
exterior life, a particular education.
Under these considerations, the occupations of mankind might be
divided into three classes. The first would comprehend all those,
which especially regard the senses, such as painting, music, and
sculpture, the acts of the perfumer and the cook, and in a word
all those the results of which are productive of pleasure to the
senses. In the second would be ranged the occupations, wherein the
brain is chiefly called into action; such as poetry, the sciences
of nomenclature, the mathematics and metaphysics. The occupations
of dancing, equitation, and the mechanic acts would form the third
class.[46]
Each several occupation then of the individual, brings into
permanent activity, some one organ in particular, and gives it a
peculiar perfection. The ear of the musician in a piece of harmony,
and the eye of the painter in a picture, distinguish many things
which entirely escape the vulgar. It frequently happens that this
perfection of action, is accompanied in the more exercised organ
with an excess of nutrition: this we may frequently observe in the
muscles of the arm of the baker, in those of the inferior limbs of
the dancer, and in those of the countenance of the player.
In the second place I have asserted that society contracts the
sphere of action, which should naturally belong to many of the
external organs. Indeed, for the sole reason that any one of
them is the more occupied, the others must be less so, and lose
in aptitude what is gained by the single organ. The most common
observation will prove this truth at every moment.
Examine the philosopher, who in his abstract meditations, and in
the silence of the closet condemns to inaction his external and
locomotive powers. Examine him by chance attempting any exercise
of the body, and you will laugh at his awkwardness and air of
constraint; his sublime conceptions astonish, the heaviness of his
movements is amusing.
Examine on the contrary the dancer, who by the lightness of his
steps exhibits apparently to the eye whatever the graces of fable
have set before the imagination. It might be imagined perhaps
that the profoundest meditations, have been productive of such
felicity of motion; but let him be conversed with, and nothing very
surprising will be found in the man.
The observing mind, which analyses the different individuals of
society at every moment, will be led to similar remarks. Perfection
of action in the locomotive organs, concurring with a like
perfection of intellect, will seldom be found.
V. _Of the laws, which regulate the education of the organs of the
animal life._
It is manifest then that society inverts the natural order of
education in the animal life, and that it irregularly distributes
to the different organs of this life, a perfection which they would
otherwise enjoy in a more uniform proportion.
A determined sum of power, has been attributed to every individual,
which sum must always remain the same, whether it be equally or
unequally distributed, accordingly the activity of one organ must
imply more or less inactivity in the others.
This truth will conduct us to the fundamental principles of all
social education whatever; namely, that no individual at the same
time, should be applied to many studies, even if it be wished
that he should succeed in all of them. Philosophers have long
insisted upon this maxim, but I doubt whether the moral reasons
on which they have founded it, are all of them together worth
this single and beautiful physiological observation by which it
is demonstrated, that for the purpose of augmenting the powers
of one organ, there are no other means than those of diminishing
the powers of the others. On this account I shall dwell upon this
observation, and prove its truth by a variety of facts.
The ear, and especially the touch, acquire in the blind man, a
perfection which would hardly be credited, were not its reality
proved by daily observation. The deaf and dumb possess in the eye
an accuracy of sight, which is unknown to those, with whom the
powers of the ear and utterance are unfolded. Little connexion with
external objects, enfeebles the senses of persons who are subject
to ecstasy, but gives the brain a power of contemplation, such as
to make it appear, that every part of the animal life, excepting
that organ, during such affection is in a state of sleep.
But what occasion is there for seeking in extraordinary facts, the
proof of a law which the animal in its healthy state exemplifies at
every moment. Let us consider in the series of animals the relative
perfection of each organ, and it will be seen at once, that where
any one of them is excellent, the others are less perfect. The
eagle, which has a very piercing sight, has but a very obtuse
sense of smell; in the dog, the latter sense is extremely fine,
the former dull. The sense of hearing is particularly acute in the
hare, that of touch in the bat; the cerebral action predominates in
the monkey, and vigour of motion in the feræ.
Every species then possesses some particular division of its animal
life, in a degree of excellence superior to that of the others. Not
a single instance will be found, where the perfection of one organ
does not appear to be acquired at the expense of the others. Man
in general, abstraction being made of every other consideration,
has the ear particularly good, and in the natural order of things,
this must be so; because his speech, which exercises the ear
incessantly, is for this organ a permanent cause of activity, and
therefore of perfection. And not only in the animal life is this
law remarkable; but it appears to have place also, in all the
phenomena of the organic life. The morbid affection of one of the
kidneys, of one of the parotid glands, will double the secretion of
the other.
Let us now examine what happens in the process of digestion.
Each system at such time is the seat of an exaltation of the
vital powers. Immediately after the entry of the aliments into
the stomach, the action of all the gastric viscera is augmented,
the powers of life are concentrated about the epigastrium, and
abandon the organs of the external life; from thence arise, as
authors have observed, the lassitude, the inaptitude of the senses
to the reception of external impressions, the tendency of the
individual to sleep, and the cold which is so frequently felt in
the integuments.
The gastric digestion being completed, the vascular succeeds, and
the chyle is introduced into the circulatory torrent, for the
purpose of undergoing the influence of this system, and that of
respiration; accordingly the blood-vessels and lungs become in
their turn, the focus of an increased action, the pulse rises, and
the movements of the thorax are precipitated.[47]
It is then the glandular, then the nutritive system which enjoy a
marked superiority in the state of their vital powers. Lastly, when
these powers have been successively developed, over all the system,
they return to the organs of the animal life, the senses resume
their activity, the functions of the brain their energy, the
muscles their vigour. Whoever reflects upon what he has experienced
after a somewhat copious repast, will be easily convinced of the
truth of these remarks.
In this way, the whole of the functions represent a species of
circle, of which the one half belongs to the organic, the other to
the animal life, the vital powers seem successively to traverse
these two halves. When they are found in one half, the other is
proportionably deprived of them, nearly in the same manner as every
thing appears to languish and be reanimated in the two portions
of the globe, accordingly as the sun refuses, or sheds down his
beneficent influence.
Should any farther proof be required of this inequality of
distribution with regard to the vital powers, we may find it in the
process of nutrition. This process has always an excess of action
in some one of the organs, which at such time may be said to live
more than the others do. In the fœtus, the brain and the nerves,
the inferior members after birth, and at the age of puberty, the
genital parts and breast appear to grow at the expense of the
others.
From such a variety of considerations, we may establish the
following to be a fundamental law of the distribution of the vital
powers, namely, that when they increase in one part, they decrease
in the rest of the living œconomy, that the sum of them can never
be augmented, and that they only transfer themselves successively
from one organ to another. By the help of these general data,
it is easy to perceive why we cannot at the same time attain to
perfection in the various parts of our animal life, why we cannot
at the same time excel in all the sciences.
Universality of knowledge in the same individual is a chimera;
it is repugnant to the laws of our organization, and if history
afford us some few instances of extraordinary men, who have thrown
an equal light upon many of the sciences, such instances are but so
many exceptions to the common laws of nature; for who are we, that
we should venture on the pursuit of many things at once, and hope
to attain in all of them a perfection, which for the most part,
even when we have but a single object in view, escapes us?
Were we capable of following at once a number of occupations,
such occupations would be those which have the greatest analogy
among themselves with respect to the organs which they bring into
exercise: and by restraining ourselves in this way within a narrow
circle, we may, indeed, with a greater degree of facility excel in
many parts; but even here the great secret of being superior in any
one of them, is that of possessing but a mediocrity in the others.
Let us take, for example, the sciences, which bring into action
the functions of the brain. We have seen that these functions
relate especially to the memory, which presides over nomenclature;
to the imagination, under the empire of which, is poetry; to the
attention, which is chiefly excited by the details of calculation;
and to the judgment, whose dominion embraces the whole of the
sciences of reasoning. Now it is manifest from daily observation,
that not one of these different operations of the mind is to be
developed but at the expense of the others.
The habits of reciting the beauties of Corneille or Racine, we
might naturally suppose would enlarge the mind of the actor; what
can be the reason that from such habit he does not acquire an
energy of conception beyond that of the vulgar? The reason depends
in part, no doubt, upon the natural disposition of the man, but at
the same time may be deduced from the greater efforts of memory,
and the faculty of imitation, which such a person is obliged to
exert: for the purpose of enriching these, the other parts of the
brain are in a manner plundered.
Accordingly, when I perceive an individual, desirous at the same
time of excelling by address of hand, in the operations of surgery,
by depth of judgment in the practice of medicine, by extent of
memory in botany, and by force of attention in metaphysical
contemplation, methinks I see a physician, who, for healing a
disease, for the purpose of expelling, according to the old
expression, the morbific humour, at the same time undertakes to
augment the whole of the secretions by the simultaneous use of
sialagogues, diuretics, sudorifics, emmenagogues, &c. &c.
But would not the slightest acquaintance with the laws of the
economy, suffice for hinting to such physician, that one gland
pours forth a greater quantity of fluid, only because the others
secrete a less? Should he not know that such a variety of medicines
can operate in no decided way, and that to exact too much of
nature, is frequently the means of obtaining nothing? The same
may be asked of the individual who is desirous of simultaneous
perfection, both in the bodily and mental exercises, who should
pretend to double or triple his relative life, when nature has
willed that he should only have the power of detaching from some
few of his organs, some few degrees of force, which may be added to
one or more of his other organs, and by no means that of increasing
the sum of these powers.
Do we wish that any one organ in particular shall attain to
perfection, we must condemn the others to inaction. We castrate
men to change their voices; it is astonishing that the barbarous
idea of depriving them of sight has not been found out also for
the purpose of rendering them musicians, since it is well known how
acute the sense of hearing is in the blind. The child, who should
be destined to music, ceteris paribus, would make a much more rapid
progress, were his ears to be assailed by harmonious sounds only,
and every thing removed which might be capable of exercising his
other senses.
It is a truth, then, that our superiority in such or such an art
and science, may almost always be measured by our inferiority in
other respects; and that this general maxim which the greater
number of the ancient philosophers have insisted on, but which many
of our modern ones would willingly overturn, has for its foundation
one of the great laws of the animal economy, and will ever be as
immutable as the base on which it rests.
VI. _Of the education of the animal life as to duration._
The education of the organs of the animal life, is prolonged for
a time which we cannot determine, as it is influenced by such a
variety of circumstances; but the peculiarity of this education
consists in its being the business of each age, to bring to
perfection certain organs in particular.
In childhood, the senses more especially are educated; every thing
seems to relate to the development of their functions. Environed
with bodies which are new to him, the little individual seeks to
know them all; he maintains in a sort of perpetual expectation
those organs by which his connexions with what is near him are
established, and undoubtedly his sensibility is excessively
developed. His nervous compared with his muscular system, is
proportionally very great; accordingly for the dissection of the
nerves, we always prefer the bodies of children.
With the education of the senses, the improvement of the functions
of the brain which relate to sensation is necessarily connected. In
proportion, then, as the sum of the sensations becomes enlarged,
the memory and imagination begin to come into play. The age which
follows infancy, is that of the education of those parts of the
brain in which these faculties are seated.--It is then, that there
have existed a sufficient number of antecedent sensations for the
exercise of the memory, and for the discovery of the type of those
illusory sensations which it is the business of the imagination to
assemble. On the other hand, the little activity of the judgment at
this epoch is much in favour of the energy of these two faculties;
and then the revolution which puberty brings on, the taste which it
develops, and the desires which it creates, contribute very much to
extend the sphere of the latter of them.
When perception, memory, and the imagination have been perfected,
when their education is finished, that of the judgment commences,
or rather becomes more active, for the judgment begins to be
exercised upon the very first materials, with which it is
presented. At this epoch the functions of the senses, and partly
those of the brain have nothing more to acquire, and all the powers
of the individual, are concentrated upon the education of the
judgment.
Hence it is manifest, that the first portion of the animal life, or
that by means of which we are acted on from without, and reflect
such action, has at each age a division, which is then particularly
unfolded. The first age is that of the education of the senses, the
second that of the enlargement of the imagination, the third that
of the development of the judgment.
We should never then prescribe the study of the sciences, which
exact the exercise of the judgment, at an age when the senses are
especially in action; but follow in our artificial methods of
education, the same laws which preside over the natural education
of the organs. The child should be applied to music and design;
the adolescent, to the sciences of nomenclature, and the belles
lettres; the adult, to the exacter sciences, where facts are
connected by a process of reasoning. The study of logic and the
mathematics, terminated our ancient plan of education; it was one
advantage at least among its numerous imperfections.
As to the second portion of the animal life, or that by means of
which the animal reacts upon external bodies, the state of infancy
is characterized by the number, the frequency, and feebleness
of its motions; adult age by their vigour; and adolescence by a
mixture of the two. The voice, however, does not appear to follow
these proportions, but is subject to an influence which proceeds
especially from the organs of generation.
I shall not dwell upon the different modifications, which with
respect to the animal life are derived from sex, climate, and
season. So many have treated of these questions, that it would be
difficult to add to what has been said upon them.
In speaking of the laws of education, as they affect the organs of
the external life, I have supposed these organs to be in a state
of complete integrity, and possessed of whatever is necessary to
their perfection.--If they be feeble or delicate, if any defect
of conformation exist in them, these laws will only be applicable
more or less; for it is manifest that the habit of judging will
not rectify the judgment, if the brain be badly constituted; and
that the frequent exercise of the larynx and voluntary muscles,
will never make up for the irregularity of action occasioned by
irregularity of conformation.
FOOTNOTES:
[41] It is unfortunate that Bichat makes use of the word density,
as he seems to be ignorant of its true signification.
The resistance, which the womb offers to the fœtus that strikes
against it, is wholly independent of density, and results only from
the greater or less flexibility of its parietes. Cork is much less
dense than mercury, and yet it offers to the finger, when pressed
against it, a much greater resistance.
[42] Of these four sources of sensation, the first, whatever Bichat
may say, exists in the fœtus before birth, and the other three, do
not exist some hours after; the eye is insensible to light, the ear
to sound, and the taste is not really in exercise when the first
food creates in the organ an unaccustomed sensation.
[43] Philosophers and physiologists accord to the touch a great
preeminence over the other senses. The senses of seeing, smelling
and hearing are, say they, the sources of a thousand illusions.
The touch alone is exempt from them, and even rectifies the errors
which come from elsewhere; _the touch is the sense of reason_.
It is undoubtedly a delightful prerogative; but let us see if
it is incontestable. And first does the touch never deceive us?
All children know an experiment which proves the contrary. If
we cross two fingers of the same hand, and place in the angular
space between their extremities a small body which touches both of
them, the touch will give the sensation of two distinct bodies.
It is then true that the touch may become a cause of errors; it
no doubt serves to rectify those of the other senses, but do not
these in their turn often defend us from the errors of the touch?
If the sight were not almost constantly in exercise, the errors of
touch would be much more numerous; we can judge of them by what we
experience when we are in the dark. If we were to take from one man
the use of his eyes, and from another that of his hands and the
exercise of touch as much as possible, we should see which would be
the most embarrassed, which would make the most false judgments.
[44] This assertion is not correct, and the voice, at the earliest
age, has consonances peculiar, not only to the species, but even to
the individual. The man accustomed to the very striking differences
of the articulate sounds of speech or the distinct sounds of music,
distinguishes with difficulty the differences in cries; but the
animals to whom the cry is the habitual medium of expression are
not deceived in the same way; the ewe, in the midst of a whole
flock, distinguishes the voice of her lamb, and this soon learns to
recognize the voice of its mother.
[45] The locomotive organs do not require a long education; as we
see in animals whose organization, at the moment of birth, is no
obstacle to motion. A young kid in an hour after, will stand on its
legs, and before the end of the day we often see it skipping. The
partridge runs as it comes out of the shell.
[46] The idea of classifying human occupations, according as
they bring in play the organs of the senses, the intellect or
locomotion, is a wild and useless one. This division besides is
made in a way altogether defective, since in the first class it
is the result of the occupations which put in play the organs,
whatever may be the means of execution; in the second it is the
occupation itself, whatever may be the results, and in the third,
it is at the same time the execution and the result.
[47] We know that at a certain period of digestion the pulse rises
and respiration is accelerated; we know it, I say, but we do not
know the immediate causes of the phenomenon. Is it a reason, in
fact, because a little chyle enters the lacteal vessels that the
heart should accelerate the course of the blood in a system of
vessels entirely distinct from these? Because afterwards this
chyle, mixed in a small proportion with the venous blood, goes with
it through the lungs, is it a reason that the motions of the lungs
should be accelerated? Undoubtedly not; besides, the acceleration
is not successive in these two functions, as Bichat seems to imply.
The one is the necessary and immediate consequence of the other.
But why does the action of the heart increase in this second period
of digestion? We cannot tell; nor do we know why it diminishes in
the first; for to think of explaining it by saying that the vital
forces are then concentrated at the epigastric region, is a mere
illusion; it is only changing the expression of the phenomenon, and
clothing it in a hypothetical form.
CHAPTER IX.
OF THE ORIGIN AND DEVELOPMENT OF THE ORGANIC LIFE.
We have just now seen that the animal life, which is inactive in
the fœtus, is developed after birth: we have also followed up the
particular laws of its development. On the contrary, the organic
life comes into action almost as soon as the fœtus is conceived;
for as soon as the least organization is apparent, the little heart
will be seen protruding its blood on all sides. The heart is the
first formed part, the first in action: now, as all the organic
phenomena depend upon it, we may readily conceive in what way the
functions of the inward life are thrown into exercise.
I. _Of the mode of the organic life in the fœtus._
Nevertheless, the organic life of the fœtus, is not the same as
that which the adult is destined to enjoy. Let us enquire into the
reason of this difference.
We have said that the organic life is the result of two great
orders of functions, of those namely of assimilation and
decomposition, so as to form an habitual circle of creation and
destruction. Now in the fœtus this circle is singularly contracted.
For in the first place, the functions of assimilation are much
fewer in number; the molecules before they arrive within the
organs which they are destined to create, are not submitted to so
many actions; they penetrate the fœtus already elaborated by the
digestion, circulation, and respiration of the mother. Instead of
traversing the apparatus of the digestive organs, which at this age
appear to be almost inactive, they enter at once into the system
of the circulation; the road which they have travelled is less, it
is not requisite that they should be presented to the influence
of respiration; and accordingly the fœtus of the mammalia has in
its preliminary organization a near analogy with that of the adult
reptile, in which but a small part of the blood at its issuing from
the heart, is sent into the vessels of the lungs.[48]
The molecules of nourishment in this way pass almost directly from
the circulating torrent into the nutritive system. The general
process of assimilation, then, is much less complicated than that
of the following age.
On the other hand, those functions which habitually decompose
the organs, which clear the system of substances already become
injurious and foreign to its nature, are at this age but very
inactive. Neither the pulmonary exhalation, nor sweating, nor
transpiration have as yet commenced: the bile, urine, and saliva
are but small in quantity, if compared with what they are destined
at a future time to be, so that the portion of blood from which
they are to be made in the adult, in the fœtus is almost entirely
expended on the system of the nutritive organs.
The organic system of the fœtus, then, is remarkable--on the
one hand, for the extreme promptitude of its assimilation, a
promptitude depending on the very small number of the functions
concurring to that end; and on the other, for the extreme inertia
of its decomposition, an inertia depending on the little activity
of the different functions, which are the agents of this great
process.
It is easy from the foregoing considerations to account for the
rapidity which characterizes the growth of the fœtus; a rapidity
which is manifestly out of all proportion with that which takes
place at any other age. Indeed, while every thing is in favour of
the progression of the nutritive matter towards the parts where
it is destined to be put down, every thing at the same time seems
to oblige such matter to remain in the place where it has been
deposited, the emunctories of the system being wanting.
To the great simplicity of assimilation in the fœtus, we may
add the great activity of the organs which contribute to it
an activity, which depends upon the more considerable sum of
vital power which they then partake. All the powers of the
economy, indeed, appear to be concentrated upon the system of the
circulation and nutrition; the functions of digestion, respiration,
secretion and exhalation, are exercised but obscurely.[49]
If we now observe that the organs of the animal life, which are
condemned to a necessary inaction, are the seat at the same time of
a very small portion only of vital power (the surplus of this being
thrown upon the organic life) it will be easy to perceive, that
almost the whole of the powers which are afterwards to be developed
upon the two systems in general, will be then concentrated upon
those which serve to nourish and compose the different parts of the
fœtus, and that in consequence the functions which concur to the
process of nutrition and growth, must at that age be the seat of an
extreme energy.
II. _Development of the organic life after birth._
Immediately after birth, the organic life of the child has a great
addition made to it; its extent is almost doubled, for not only
are many of the functions which did not before exist at such time
added, but those which existed previously are much enlarged. Now in
this remarkable revolution of things, a law directly the contrary
of that which presides over the animal life is observed; for the
organs of this life, whether they be newly brought into exercise,
or simply receive an increase of action, need no education; they
suddenly attain to a perfection, which those of the animal life do
not acquire, otherwise than by long habitude. A rapid glance upon
the development of this life, will be sufficient to convince us of
the truth of the above observation.
At the instant of birth, digestion and respiration, with a great
part of the exhalations and absorptions commence. Now after the
first inspirations and expirations; after the elaboration in the
stomach of the first milk, which is taken in by the infant, as soon
as the exhalants of the lungs and the skin have once rejected some
small portions of their respective fluids, the respiratory, the
digestive and exhalant organs, have as perfect an action as they
ever will have.
At the same time all the glands, which slept as it were, which
poured forth but a very small quantity of fluid, are awakened from
their torpor by the stimuli of the various substances which are
applied to the mouths of their excretory ducts. The passage of
the milk at the extremities of the stenonian and wartonian ducts,
of the chyme at the end of the choledochus and the pancreatic
duct, the contact of air with the orifice of the urethra, awaken
into action the salivary glands, the pancreas, the liver, and
the kidneys. The air in like manner upon the inner surface of
the trachea and the nostrils, and the aliments upon that of the
digestive passages, are the excitants which rouse these parts into
action.[50]
It is then also that begin the various excretions of the system:
now if we examine well the different organs which concur to the
above mentioned phenomena, we shall find that they require no sort
of education.
I shall not inquire into the reason of this difference in the
development of the two lives. I shall only observe that it is out
of the power of any one of the inward organs, to acquire a marked
degree of superiority over any other, for the same reason that they
all of them attain, immediately upon entering into action, as great
a perfection as at any time they are destined to possess.
Nevertheless there is nothing more common than the predominance
of one system of the organic life over the other systems; this
is sometimes the vascular, sometimes the pulmonary apparatus, at
other times the organs of digestion, and the liver especially, have
the greater degree of development, and decide on the particular
temperament of the individual; but the cause of this sort of
constitution depends on primitive organization, on the structure
of the parts, on their conformation. Such superiority is by no
means the effect of exercise or habit, for the fœtus and the
child display the same phenomena, in as much reality though less
apparently indeed, than adolescence, or manhood.
In the same way, the debility of any particular system of the
internal functions, may depend either on original constitution, or
on some accidental vice or disease, by which, while the others
have remained untouched, its constitution may have been impaired.
Such then is the great difference of the two lives of the animal,
with respect to inequality of perfection in the organs. In the
animal life, the predominance or inferiority of one system, with
relation to the others, depends almost entirely upon its activity
or inertia, on its habitude of acting or not acting. In the organic
life on the contrary, such states are immediately connected with
the texture of the organs, and never with their education.
From hence also we have the reason why physical temperament, and
moral character, are not susceptible of change from education,
which so prodigiously modifies the actions of the animal life, for
as we have seen, they both of them belong to the organic life.
The character is, if I may so express myself, the physiognomy of
passions; temperament, that of the internal functions: now the
one and the other being at all ages the same, having a direction
which habitude and exercise can never alter, it is manifest that
they must ever be withdrawn from the influence of education. The
violence of the temperament may indeed be moderated, for the powers
of the judgment, and reflection may be augmented, and the animal
life strengthened in such way as to give it a capacity of resisting
the impulses of the organic life; but to attempt an immediate
alteration of the character, or of the passions, which are its
habitual expressions, is an enterprise analogous to that of the
physician, who should attempt to elevate or depress, (and that, for
the entire life of the patient,) the ordinary contracting powers of
the heart and arteries.
We should observe to such physician, that the circulation and
respiration, are not under the dominion of the will; and that they
cannot be modified excepting in passing into a state of disease.
The same observation might be made to those, who imagine that the
character, and consequently the passions may be modified.
FOOTNOTES:
[48] I am persuaded that the still very obscure theory of the
fœtus might be elucidated by that of animals who have a similar
organization. For example, in the frog, in whom but little blood
goes through the lungs, the heart is a simple organ, with a
single auricle and ventricle; there is a communication or rather
continuity between the two systems, venous and arterial, whilst in
the mammalia, the vessels in which the red blood circulates do not
communicate with those which carry the black blood, except it be by
the capillaries.
In the fœtus, the foramen ovale and the ductus arteriosus also
render very evidently the arteries and veins continuous; in
the fœtus the heart is likewise a simple organ, not forming,
notwithstanding its partitions, but one cavity whilst it is double
after birth. The two kinds of blood mix at this period, as in
reptiles. Now, I shall prove hereafter, that in the child who has
breathed, this mixture would soon be fatal; that the black blood,
circulating in the arteries, would very quickly produce asphyxia
in the animal. Whence arises then this difference? It cannot be
studied in the fœtus; it is necessary perhaps to search for it
in frogs, salamanders and other reptiles, which can, by their
organization, be a long time deprived of air without dying, a
phenomenon which approximates them to the mammalia while living in
the womb of the mother. Till these very important researches are
made, the history of respiration will be incomplete.
[49] This explanation is no doubt ingenious, but it is
insufficient, since the causes which Bichat assigns for the
rapidity of the growth of the fœtus cease entirely at the moment of
birth, and yet the growth continues for a long time after to be as
rapid.
[50] When two phenomena are seen to follow each other immediately,
we are naturally led to consider one as the cause of the other.
_Post hoc ergo propter hoc._ It is a form of reasoning which is
very often abused. Food taken into the mouth touches the orifice of
the salivary ducts, the fluid flows out, and it is then concluded
that the salivary gland has been excited by the impression made on
the extremity of its canal. At the moment of birth, the orifice
of the urethra is exposed to the contact of the air, and soon the
kidneys begin to secrete; then it is the impression of the air
on the urethra that has produced their action. But is not this
contact of the food in the one case, and of the air in the other
an accidental and purely accessory circumstance? Do we believe,
that if by any cause the opening of the prepuce was entirely
obliterated, the secretion of urine would be prevented? Do we not
know that if instead of taking into the mouth savoury food, it
is brought near to it, the saliva flows not less, or in vulgar
language the mouth waters? There is however no contact, there is
not any mechanical or chemical impression in the orifice of the
salivary ducts.
CHAPTER X.
OF THE NATURAL TERMINATION OF THE TWO LIVES.
We have just now seen, that the two lives commence at distant
epochs; we have seen them developing themselves according to laws,
which are exactly the reverse of each other. I shall now attempt
to describe them, as they terminate; and this they do in a very
different manner also, assuming characters at such time as distinct
and separate, as those which they possess during the periods of
their activity. In this place, I shall speak of natural death only;
those deaths, which originate in accidental causes, will be the
object of the second part of this work.
I. _In Natural Death the animal life is the first to cease._
Natural death is remarkable for the following reason chiefly:--it
terminates the animal life, a long time before it puts an end to
the organic life.
He who dies in consequence of a very prolonged old age, dies in
detail; his exterior functions are finished, one after the other;
the senses are shut up successively; the ordinary causes of
sensation pass over them, and do not affect them.
The sight grows dull and confused; it ceases at length to transmit
the images of objects: this is the blindness of old age; sounds
also, after a certain time, affect the ear confusedly; the organ
at last becomes entirely insensible. The cutaneous covering of the
body grows hard and dry; it is the seat of an obscure and imperfect
touch. Besides which, the habitude of feeling has blunted the
power of feeling; at the same time all the other organs which are
dependent on the skin, grow weak and perish; the hair falls, it is
deprived of the juices by which it was nourished: to continue our
description, odours make but a feeble impression upon the nostrils.
The taste indeed is a little more kept up; but let it be remarked
that this sense is connected with the organic as much as with the
animal life, and is therefore necessary to the internal functions:
In this way, when all agreeable sensations have fled the old man,
when their absence has already broken in part the connexions, which
attach him to the world, his taste remains with him still; it is
the last thread to which is suspended the pleasure of existence.
In this way, isolated in the midst of nature, already deprived of
the greater number of the functions of the sensitive organs, the
old man is soon to suffer the loss of the common action of the
brain, for it is manifest, that there can scarcely be any farther
perception, for the very reason that there is nothing farther
coming from the senses. Meanwhile, the imagination lessens and is
soon annihilated.
The memory of present things is destroyed: the old man in an
instant forgets what is told him, because his external senses
enfeebled and already dead, as it were, in no wise confirm what
is intimated to him by the mind alone. Ideas escape him when the
images, which are traced by the senses, do not keep their hold. On
the contrary, the remembrance of the past remains with him, that
which the old man has formerly known, has been taught him or at
least confirmed to him by his senses.[51]
He differs from the child in this respect; the child judges only
from the sensations which he experiences, the old man from those,
which he has experienced.
The result of the two states is the same, for the judgment is
equally uncertain, whether founded exclusively upon actual or past
sensation. Its accuracy depends upon the due comparison of the two.
No one can be ignorant, that in the judgment which we form from
visible objects, the actual impression would frequently deceive
us, were we not to rectify the error by what we are enabled to
recollect, and may we not observe that past sensations, in a short
time grow confused, if the features of the picture, which they have
left with us, be not retraced by new and analogous impressions?
The present then, and the past with regard to sensation, are
equally necessary for the perfection of the judgment. If either
the one or the other be wanting there cannot be any comparison
made between the two, and in consequence there must be a want of
precision in the judgment.
For these reasons, the first and the latter ages of man, are
equally remarkable for imbecility. Old age is second infancy. The
two periods of life resemble each other with regard to want of
judgment; they differ only as to the cause of such defect.
The interruption of the functions of the brain of the old man,
is a consequence of the almost entire annihilation of the
sensitive system with him; in the same way does the weakness of
the locomotive power, succeed almost inevitably to the inactivity
of the brain. This organ in fact re-acts upon the muscles, in
proportion only as the senses act upon it.
The movements of the old man are few and tardy; he changes with
difficulty the attitude, into which he has thrown himself; seated
near the fire, and concentrated within himself, a stranger to every
thing without him, he passes his days there, deprived of desire, of
passion, and sensation; speaking little because he is determined by
nothing to break his silence, yet happy in feeling that he still
exists, when almost every other sentiment is gone.
The rigidity of the muscles however, and the diminution of their
contracting powers, is another cause of inactivity in the old
man, and doubtless has its influence; but it is by no means the
principal one, since the heart and the muscular fibres of the
intestines, contract the same rigidity, and are deprived of their
powers of moving, in a very different way from that, in which the
voluntary muscles lose it. With the voluntary muscles, it is not
so much the power as the excitant of the power which is lost. If
it were possible to compose a man with the senses and brain of old
age, and the muscles of youth, the voluntary motions of such man,
would hardly be more developed for the reasons which I have given.
From the above it is easy to see that the external functions of
the old man are extinguished by degrees, and that his animal life
has almost entirely ceased, while his organic life is still in
activity. Under this consideration, the state of the animal about
to suffer a natural death, is nearly similar to that of the fœtus
in utero, or of the vegetable which lives within itself only, and
for which external nature is absolutely silent.
If we now recollect that sleep entrenches more than a third upon
the duration of the animal life, if we add to this the total
absence of such life for the first nine months of existence, and
its almost entire inactivity during the latter period of existence,
it will be easy to calculate the great disproportion of its
duration, when compared with that of the organic life which is
exercised uninterruptedly.
But wherefore when we have ceased to exist without, do we continue
to exist within, since our sensations and above all, our powers of
locomotion, are especially destined to place us in relation with
those substances, which are to nourish us. Wherefore are those
functions enfeebled in a greater disproportion than the internal
functions, and why is there no exact relation in the times of their
cessation.
I cannot entirely resolve this question. I shall only observe that
society has an especial influence in creating this difference;
for man in the midst of his fellow-creatures makes a very great
use of his animal life; the springs of it are habitually more
fatigued than those of his organic life, and worn away under the
influence of society; the eye by artificial light, the ear by
sounds too frequently repeated, and above all by those of speech,
which are wanting to other animals;[52] the smell in like manner
is debilitated by factitious odours, the taste by savours, which
certainly are not natural, the touch and the tact by constant
attrition of dress,[53] and the brain by too incessant thinking.
We live then externally with excess. We abuse our animal life;
it is circumscribed by nature within limits which are too much
enlarged by us for its duration; thus it cannot be surprising that
it should cease so soon. In fact we have seen the vital powers
divided into two orders, the one appertaining to this life, the
other to the organic life. These two orders may be compared to
two lights which burn at the same time, and which have only a
determined quantity of materials for aliment. In which case, if
the one be agitated by a stronger wind than the other is, it must
necessarily be the sooner extinguished.
Yet social influence notwithstanding is very advantageous to man.
It gradually disengages him from those bonds which attach him to
life, and renders the instant of death less terrible.
The idea of our last hour, is painful only because it puts an end
to our animal life. The borders of the tomb are beset with terrors,
which will all be found to originate in the thought of such
privation.
It is not the pain of death, which we fear; how many dying men
are there for whom the gift of existence would be precious, though
purchased at the expense of an uninterrupted series of suffering!
If we look at the animal which lives but little externally, he by
no means trembles at beholding the instant of his death.[54]
Were it possible to suppose a man, who in dying should lose his
internal functions only, such man would look upon his death with
an indifferent eye, because he would feel that the blessings of
existence, are attached to the powers of feeling the influence of
nature and society.
If the animal life then be terminated gradually, if each of the
bonds by which we are capable of the pleasures of living, be broken
by little and little, such pleasures will escape us imperceptibly,
and the old man will have forgotten the value of life, when it is
about to be taken from him; such destruction will resemble that of
the vegetable only.
II. _The Organic Life in natural death does not terminate as it
does in accidental death._
The organic life remains with the old man after the almost total
loss of his animal life, and terminates in a very different manner
from that which is exemplified in the case of violent and sudden
death. The latter has two periods, the first of which is marked
by the sudden cessation of respiration and the circulation, the
second by the slow and gradual extinction of the other organic
functions.
The parietes of the stomach, for instance, continue to act upon
the aliment which may be found there, the juices of the stomach
continue to dissolve it. The experiments of the English and Italian
physicians upon absorption, (experiments the whole of which I have
repeated) have proved that this function not unfrequently remains
in a state of activity, after the general death of the body, and if
not as long as some have supposed, at least for a very considerable
interval. Discharges of urine and feces are often observed to take
place many hours after sudden death.
The process of nutrition also continues to be manifest in the hair
and in the nails; the same would doubtless be the case in all the
other parts, as well as in the secretions, could we observe the
insensible movements of which their functions are the result. The
heart of the frog being taken away, the capillary circulation may
still be seen under the influence of the tonic powers. The body is
very slow also in losing its animal heat.[55]
I might augment the above observations with a number of others,
which would go to prove the same assertions; on the contrary,
in the death which is the effect of old age, the whole of the
functions cease, because they have each of them been successively
extinguished. The vital powers abandon each organ by degrees,
digestion languishes, the secretions and the absorptions are
finished, the capillary secretions become embarrassed; lastly, the
general circulation is suppressed. The heart is the ultimum moriens.
Such, then, is the great difference which distinguishes the death
of the old man, from that which is the effect of a sudden blow. In
the one, the powers of life begin to be extinguished in all the
parts, and cease at the heart; the body dies from the circumference
towards the centre: in the other, life becomes extinct at the
heart, and afterwards in the parts. The phenomena of death are seen
extending themselves from the centre to the circumference.
FOOTNOTES:
[51] If the old man preserves with difficulty the memory of the
most recent events, whilst he often retraces with the greatest
ease the recollection of the most distant ones, it is not because
the first have been more faithfully transmitted to him by his
senses, but because these events had produced a greater impression
on him. This is so true, that failure of the memory is sometimes
remarked in old people who have their senses in perfection. On the
other hand, very imperfect sensations may produce a very lively
impression. A connoisseur in painting, when his sight is very bad,
experiences in seeing a beautiful picture, a hundred times more
pleasure, than one who is indifferent to it, though he examines it
with good eyes, and the connoisseur preserves the image of it long
after the other has lost it. We do not perceive the recollection of
things, unless there is some circumstance connected with them that
makes a lively impression; but in the same event, this circumstance
will not be the same in all individuals, and it is sometimes by the
most trifling of all that a man fixes the fact in his memory.
[52] This failure of the senses appears in animals as well as
man, and it may be observed in those whom we suffer to grow old
among us. We often see dogs becoming blind and deaf; and these
infirmities are perhaps more common in them than in man. But as
these animals are rarely permitted to arrive at extreme old age, we
have not often an opportunity of observing them.
[53] By defending the skin from the shock of external bodies, and
by preserving it from the variation of temperature, dress very
certainly preserves its sensibility, and far from impairing the
sense of touch, as Bichat maintains, it acts as a circumstance
favourable to its preservation.
[54] The animal no doubt does not tremble at the moment of death;
for he does not see it. His present sensation is every thing to
him. If he suffers at the approach of death, he shows it by the
usual signs; but it is only the present pain that he expresses,
he sees nothing beyond. The child is in this respect, in the same
situation as the animal.
[55] In order to ascertain the cause of the differences in the
cooling of the body after the various kinds of death, it is
necessary to examine what general conditions can have an influence
in the cooling of a body left to itself. Of these there are three
principal ones.
Under the same external circumstances, a body will cool so much the
slower. 1st. As its temperature at the beginning of the experiment,
shall be higher in relation to that of surrounding bodies; 2d. As
its surface shall be less in relation to its size; 3d. And as its
exterior parts shall be less perfect conductors of heat.
In order to see how the first condition is modified in different
cases, it is necessary to recollect what is the source of animal
heat. The blood is warmed in passing through the lungs in
consequence of the chemical phenomena of respiration; and as from
the lungs it is carried to all parts of the body, it yields to the
different organs a portion of the heat which it has received. Hence
the general temperature of the body will be higher in proportion
to the temperature of the blood, to the frequency with which this
fluid is renewed in the organs and to the quantity of it that is
brought to them, at each pulsation.
Now in diseases of long duration, the volume of blood is
considerably diminished, the activity of the heart is lessened,
and respiration is performed in an imperfect manner. Thus the body
of the patient who sinks under these circumstances has less heat
to lose than that of the man who dies suddenly, when all these
functions were performed in perfection.
Let us pass now to the second condition. The cooling, as we have
said, takes place so much the quicker as the surface of the body is
the more extended in proportion to its size; now, in the emaciation
which accompanies almost all diseases that are protracted, the size
decreases much more rapidly than the surface. Thus then, when even
at the moment of death the general temperature of the body may be
as high as in a state of health, the cooling would however take
place more quickly.
It remains for us now only to examine under what circumstances
the third condition is fulfilled in the most advantageous manner.
When an individual in full health dies, the sub-cutaneous cellular
texture usually contains a greater or less quantity of fat. Now we
know that it is one of the characters of all fat substances to be
very bad conductors of heat. Hence then a third reason which should
render cooling more slow after sudden deaths. Sometimes after a
disease, this last condition is fulfilled in another manner. In
certain derangements of the circulation, the cellular texture is
filled with serum; and as all aqueous fluids are bad conductors of
caloric, though the temperature of the body may not be very high at
the moment of death, the heat is yet preserved for a long time.
To the different causes which we have just mentioned, there is
sometimes added another which is peculiar to one kind of sudden
death. It is observed that in the midst of the same external
circumstances, the blood does not always cool with the same
quickness, and that in proportion as its coagulation is slower,
its heat is longer preserved. Now, it is a well known fact, that
when death is the result of asphyxia, the vessels are found full
of fluid blood; this is also a reason which contributes to explain
the slowness of the cooling. And it should be remarked, that
asphyxia is one of the most frequent causes of sudden death either
accidental or voluntary.
BICHAT ON LIFE AND DEATH.
PART THE SECOND.
CHAPTER I.
GENERAL CONSIDERATIONS ON DEATH.
In the first part of this work, I have explained the two great
divisions of life, together with the remarkable differences, which
distinguish the animal existing without, from the animal existing
within. I have discussed the characters which are exclusively
proper to the two lives, and the particular laws, according to
which they both of them commence, are developed and end in the
natural order.
In this second part I shall inquire in what way they accidentally
finish, in what way their course is prematurely arrested.
The influence of society suffers us but rarely to live out the
period which was intended us by nature; while almost every other
animal attains his natural end, such end in the human species is
become a sort of phenomenon. The different kinds then of accidental
death, should engage the particular attention of the physician
and physiologist. Now this sort of death may happen in two ways:
sometimes it is the result of great disturbance excited in the
economy; and sometimes it is the effect of disease.
In general it is easy enough to discover, according to what laws
the functions are terminated in consequence of any violent or
sudden attack; of apoplexy, for instance, great hemorrhagy,
concussion of the brain, or asphyxia; because in such cases the
organs of the body, excepting that which is immediately affected,
are not the seat of any peculiar lesion, and cease to act from
causes diametrically the contrary of those, which according to
the common course of things maintain them in action. Now as these
causes are partly known, their contraries may be inferred; besides,
we are capable of imitating these sorts of death upon animals,
and consequently of analyzing, experimentally, their different
phenomena.
On the other hand it is seldom in our power to produce artificially
in the bodies of animals the diseases of the human species. Were we
even possessed of such power, we should gain but little knowledge
from it: the laws of life in fact are so changed, so modified, so
altered in their very nature, by the various morbid affections to
which the parts are subject, that but very seldom can we depart
from the known phenomena of the living animal, when we undertake to
inquire into those which it exhibits in its dying moments. For such
inquiries it would be necessary to know what is that intermediate
state between health and death, in which the functions experience
so remarkable a change; a change, which has such infinite
varieties, and produces such innumerable sorts of disease. But,
where shall we find the physician, who will assert that from the
actual data of his art, he understands in such intermediate state,
the profoundly hidden operations of nature?
In these researches then, we shall occupy ourselves more especially
on those sorts of death which I first enumerated. Those, which have
been mentioned in the preceding paragraph will engage us only now
and then: besides, at my age I cannot be supposed to have acquired
a sufficient degree of medical knowledge to treat of them with
advantage.
The first remark, which the observation of the different kinds of
sudden death suggests, is, that in all of them the organic life to
a certain point may subsist, the animal life being extinct; but
that the latter is entirely dependent, and lasts not for a moment
after the interruption of the former. The individual, who is struck
with apoplexy may live internally for many days after the stroke,
externally he is dead. In this case death commences with the animal
life: if on the contrary it exerts its influence in the first place
upon any of the essential organic functions--as on the circulation
in wounds or on respiration in the asphyxiæ--the animal life is
gone at once, together with the sensible actions of the organic
life.
The red and warm-blooded animal, loses his external life at the
moment when he ceases to exist internally, the cessation of the
phenomena of his organic life is a sure index of his general death;
indeed the reality of death can be pronounced only from such datum;
the interruption of the external phenomena of life is in almost
every instance fallacious.
On what depends this difference of the manner in which the two
lives accidentally end? It is owing to the mode of that influence,
which they exercise the one over the other, to the kind of bond, by
which they are connected.
This mode of influence, this bond, appears to exist between the
brain on the part of the animal life and the lungs, or heart on
the part of the organic life. The action of one of these three
organs is essentially necessary to that of the two others; and as
they constitute the three centres, in which are terminated all the
secondary phenomena of the two lives, whenever they cease to act,
the phenomena which depend upon them must cease also, and general
death ensue.
Physiologists have been at all times acquainted with the importance
of this triple focus; and have given the name of vital to all those
functions, which have their seat in it. Under the point of view
which at present engages our attention their ideas on this head are
well worthy of notice, for every species of sudden death begins by
the interruption of the circulation, the respiration, or action of
the brain. In the first place, one of the three functions ceases,
then the others successively; so that to expose with precision the
phenomena of sudden death, we must consider them as they take place
in the three principal organs, which we have mentioned.
We shall first inquire into those deaths, which begin at the heart,
and afterwards into those, which begin in the lungs and in the
brain. I shall explain in what way, when one of these organs is
affected, the others die; and then demonstrate by what sort of
mechanism the death of the various other parts of the body ensues.
Lastly I shall determine from the principles, which I shall then
have laid down, the nature of the different species of disease,
which are peculiar to the heart, the lungs, and the brain.