TRANSCRIBER’S NOTE

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.

The cover image was created by the transcriber and is placed in the public domain.

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.

PART THE SECOND.

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.