Chapter IV: Preface: By the Author (3)

I have endeavoured, as far as possible, in classing the functions, to follow the path marked out by nature herself. I have laid, in my work upon Life and Death, the foundations of this classification, which I pursued before I published this work. Aristotle, Buffon, &c. have seen in man two kinds of functions, one which connects him with external bodies, the other, which serves for his nourishment. Grimaud brought forward again this idea, which is as great as it is true, in his course of physiology and in his memoir upon nutrition; but by considering it in too general a manner, he did not analyze it with sufficient exactness, he ranked among the external functions, only sensation and motion, he did not describe the brain as the centre of these functions, nor place the voice among them, which is however one of the great means of communication, with the bodies that surround us. He did not analyze more accurately the internal functions. He did not point out their connexion in the elaboration of nutritive matter, where each works in its turn, if I may so express myself; nor show the distinctive characters, which separate generation from all the other functions relating to the individual alone. Besides, the distinction of internal and external functions was only presented as a general sketch in his Memoir upon Nutrition, and not as a means of classification. He did not avail himself of it, in the division of the functions, in his lectures, of which many manuscripts arranged by himself, are to be met with at the present time; in these he examined, 1st. osteogony, which was treated at much length; 2d. the action of the muscles; 3d. the action of the vessels or the circulation; 4th. generation; 5th. the action of the organs of the senses; 6th. the action of the brain and nerves; 7th. digestion; 8th. secretion; 9th. respiration, &c. From this it may be perceived, that Grimaud, like preceding authors, mixed together all the functions without referring them to certain general heads.

In reflecting upon the division pointed out above, I soon saw that it was not only one of those general views, one of those great outlines, that are oftentimes made by men of genius who cultivate physiology, but that it might become the permanent basis of a methodical classification. To come at this classification I observed that it was necessary at first to refer all the functions to two great classes, one relating to the individual, the other to the species; that these two classes had nothing in common, but the general connexion that unites all the phenomena of living bodies; but a variety of distinctive attributes characterize them, which cannot be separated from them.

These two first classes being rigorously defined, and their limits established by nature, I sought to discover in each, orders equally natural; this was easy in the functions relating to the individual. In fact, this was the place for the general outline of Aristotle and Buffon; but it was not to be presented in too general a manner; the nature and connexion of the functions peculiar to each order, were to be accurately assigned.

I called the order of functions that connects us with external bodies, animal life, thus indicating that this order belongs alone to animals, that it is more with them than with vegetables, and that it is the addition of these functions that particularly distinguishes them from vegetables. I called organic life, the order that serves for the constant composition and decomposition of our bodies, because this life is common to all organized beings, vegetables as well as animals; and because the only condition of enjoying it is organization; so that it forms a boundary between organic and inorganic bodies, as animal life serves to separate the two classes that form the first.

Animal life is composed of the action of the senses which receive impressions, of the brain which perceives them, reflects, and wills, of the voluntary muscles and larynx that execute this volition, and of the nerves which are the agents of transmission. The brain is truly the central organ of this life. Digestion, circulation, respiration, exhalation, absorption, secretion, nutrition, calorification, compose organic life, which has the heart for its principal and central organ.

I place calorification here, because it is evident from what I have said under the article upon the capillary systems, that it is a function analogous to secretion, exhalation and nutrition. It is truly a separation of combined caloric, from the mass of blood. It is, if the expression is preferred, a secretion or exhalation of that fluid in every part of the body. I have not even at present given this place to heat in my physiological classification: but in reflecting upon the method of its production, it will be seen that it ought to have it.

The two orders of the first class being established, it was easy to assign those of the second, which are three in number: 1st. functions belonging to the male; 2d. those belonging to the female; 3d. those arising from an union of the two sexes and the product of this union; these are the three orders.

Such is the classification that I made in my Lectures on Physiology; it has evidently nothing in common with any of those that are found in physiological works; and if you reflect upon it a little, it will appear I think infinitely preferable to any of them. Observe in fine, that each class and each order have general and characteristic attributes that particularly distinguish them, and which being applicable to all the functions of that order, mark a difference between them and all the functions of any other order. I have pointed out moreover the distinctive attributes of animal and of organic life; I have shown that the organs of one are symmetrical, those of the other irregular; that there is a harmony in the functions of the first, a discordance in those of the second; that one commences sooner and terminates later, &c.

I have demonstrated, that the cerebral nerves belong especially to animal life, the nerves of the ganglions to the organic, which appears to me to be a remarkable difference, and which has induced me to make two systems of the nerves, that anatomists have united in one. The first, belonging to animal life, is composed of the cerebral nerves, the other to organic, is formed of the nerves of the ganglions, or what is commonly called the great sympathetic.

But it is the vital powers especially that distinguish one life from another. I have shown that one kind of sensibility and contractility belongs to animal life, and another to organic. Now as these vital properties are the principle of the functions, it is evident that the division of these properties demonstrates that that of the two lives is not an abstraction, but that it is nature herself that has fixed the limits, since she has made particular properties for each.

It is impossible to form a precise idea of the vital properties, without admitting the division I have made. How many disputes there have been, upon the subject of sensibility! Not one of them would have taken place, if the attributes of animal life had been properly distinguished from those of the organic. Certainly no one will hereafter confound in one view, as frequently has been done, the faculty that the heart has of being sensible to the entrance of the blood, without transmitting that impression, and the faculty that the skin, the other senses, the nerves, &c. have, not only of feeling the impression of external bodies, but of transmitting it to the brain, so that the sensation may be perceived.

If you include under one common name of irritability, the motions of muscles that contract only by stimuli, and those which the cerebral influence puts in action, it is impossible that you should be understood.

There has been much discussion during the last age, upon the point, whether sensibility is the same as contractility, or if these two properties can be separated. Each of the two opinions seem to have rested upon an equally solid foundation. But all these disputes will be done away, by admitting the distinction I have made in the vital properties. 1st. In animal life, then, it is evident, that contractility is not a necessary consequence of sensibility; thus frequently external objects make for a long time an impression upon us, and yet the voluntary muscles remain unmoved. 2d. On the other hand, in organic life, these two properties are never separated. In the involuntary motions of the heart, the stomach, the intestines, &c. there is first an excitement of the organic sensibility, and then an action of the sensible organic contractility. In the same manner, in the motions necessary to secretion, exhalation, &c. when the organic sensibility has been brought into action, immediately insensible organic contractility takes place. It is that they may be studied better, and appreciated more accurately, that in organic life, I separate these two kinds of contractility from sensibility. In the natural state they are inseparable. Hence why the passive sympathies of animal sensibility are very different from those of animal contractility, and make two distinct classes, whilst the passive sympathies of organic sensibility can never be separated from the corresponding contractilities. We suffer by sympathy, and are sympathetically convulsed in a distinct manner; these two things are almost always separate. On the contrary, sensation and motion in the organic sympathies are inseparable.

I could prove by many examples, that all the disputes, and all the diversities of opinion, upon the subject of the vital properties, proceed only from this cause, that those which preside over the functions of one life, have not been distinguished from those which put into action the functions of the other.

Let us return to my physiological division; I will now give a table of it, which, presenting it under one point of view, will give a more precise idea of the classification. This table comprehends, 1st. the prolegomena of the science; 2d. the exposition of the functions. In the prolegomena, every thing is referred to two great considerations; on the one hand to organic texture, described in a general manner, and on the other to life, considered in relation to its great attributes.

TABLE OF PHYSIOLOGY.

_PROLEGOMENA._

GENERAL OBSERVATIONS ON ORGANIC TEXTURE.

SECTION I.
│1st. Of the organic texture of animals.
│2d. Of simple textures, in general.
│3d. Of organs, in general.
│4th. Of the apparatus, in general.[4]

[4] In a subsequent part of this work, the author defines _appareil_,
which I have translated by the word _apparatus_, to be an assemblage
of many systems. It will be perceived that the English word in this
and some other instances is in the plural number. I should certainly
have preferred some other term more conformable to the idiom of our
own language if I had known any one that would so well have conveyed
the sense of the author. _Tr._

SECTION II.
┌1st. Of the properties of texture.
│
│2d. Division of the ┌Extensibility.
│ properties of texture. └Contractility. ┌1st. By want of extension.
│ └2d. By horny hardening.
└3d. Characters of the properties of texture.

GENERAL OBSERVATIONS UPON LIFE.