Science Of Life
( Originally Published 1913 )
WE now approach the great and intensely interesting Science of Life, improperly called Physiology,—a name which it must continue for some time to bear, because certain quacks with customary ignorance have vulgarized and distorted the term Biology, and applied it, in contempt of Greek and science, to their Mesmeric operations.
Matter endowed with a peculiar property, by us named " vital force ;"* having the faculty of nourishing itself, of reproducing itself, and, in its higher complications, of feeling; nourishing itself by a process which is identical throughout the whole series of organized beings—namely, by cellular formation; reproducing itself also by an identical process—cellular fission ; possessing, in the animal series, sensibility and locomotion, in virtue of two special tissues, the nervous and the muscular; exhibiting itself in a wondrous progression of combinations from the struetureless cell of the lowest plants up to the complex structure of the highest animals ; acting in strict conformity with certain laws, chemical and vital, and so producing all the variety of organized beings ; becoming more and more heterogeneous in organs and functions as it ascends the scale ; passing through determinate stages of germination, growth, maturity, decline, and death; everywhere indissolubly connected with the great Life of the Whole, and speaking in mysterious hieroglyphics of that " all-encompassing and all-sustaining" Power, the burden and the mystery of which for ever presses on our souls—such is the object of Biology ! To it all the other sciences are torches. It is the torch whereby we can look upon the final Social Science.
The study of Man and the study of the external world constitute the eternal two-fold problem of philosophy. As Comte says, each may serve as the point of departure of the other. Hence two radically opposed philosophies—one considering the world ac-cording to our subjective conceptions---that is to say, explaining cosmical phenomena by the analogies of our sentiments and affections ; the other considering man as subordinate to the laws of the external world, and as explicable only by the explanation of the properties of matter recognised in operation in the external world. The former of these philosophies is essentially metaphysical and theological. It rests upon the old assumption of man's mind being the normal measure of all things : it makes law the correlate of idea ; it makes the universe subordinate to man. The second is the scientific or positive philosophy.
That the Metaphysical Method should predominate in the study of Life, long after it has disappeared from Physics, and only lurks in odd corners of Chemistry, every one might have foretold ; and accordingly, except in the study of morals, we nowhere see this Method so strikingly illustrated as in Biology, with its " Vital Principle," its " Nature curing herself," and its famous notion of organized bodies being independent of chemical action. Not only are all phenomena of life more complex than chemical or physical phenomena, and hence less easily reduced to simple laws, so that because our scientific knowledge is less perfect, our metaphysical conceptions have greater scope; but the very fact, that in studying Life we go at once to the source of all Metaphysical Method, explains our being metaphysicians in our treatment of this subject. The very men who would laugh at attempts to discover the " principle of attraction," the " nature of electricity," or the " cause of affinity," content as they are with recording the Laws (Methods) which regulate phenomena, naïvely investigate the "vital principle," the " nature of Mind," the " cause of sensation." It is only of late years, and among the most eminent physiologists, that the study of Life has acquired a decisively positive character.
Every Science has its corresponding Art; because in life all our Thought has an aim in Action, under pain of becoming sterile and fantastic. But although Art is necessary as a primary impulse and concurrent aim to Science, yet at a certain period of advancement it is indispensable that we should accurately separate them. As Comte says, their respective domains are distinct though united : to one belongs knowledge, with prevision as result ; to the other power, with action as result. But as soon as Science becomes fairly constituted, it must pursue its own development without any regard to other aims than those of knowledge. 0f this the great Archimedes had a profound sentiment, when he naïvely apologized to posterity for having one instant applied his genius to practical inventions. And our brilliant essayist, Macaulay, shows a profound misconception of the nature of science in his celebrated article on Bacon—the whole purport of which is to show that Science ought to be restricted to its immediate applications. The culture of any one science would have familiarized his mind with the opposite conception, and would have taught him that whatever benefits Science has derived in the way of stimulus and direction from the necessities of the Arts, nevertheless, almost all the great developments of Science have been due to the purely speculative character it has taken. Man does not live by bread alone, thank God ! And if the energetic lower impulses are necessary at first to stimulate our higher faculties, yet these faculties once aroused suffice unto themselves !
The object of these remarks is to point out the necessity of separating Biology from Medicine, and consequently of no longer trusting the cultivation of the science to those who practically apply it,—the Medical Profession. If it were proposed to confine the culture of Astronomy to Navigators alone, loud Homeric laughter would greet the proposal ; yet those very laughers would see nothing irrational in confiding the culture of Biology to the scanty leisure of the Medical Profession. In vain do we remind objectors that Schwann, Kolliker, Henlé, Owen—indeed, most of the greatest physiologists—are either not members of the medical profession, or little more so than in name—the common prejudice is, that Biology can only be successfully studied by the "profession." But this is an evil which must spontaneously disappear before the advance of Science; especially when we come more distinctly to understand that Biology must necessarily embrace the whole phenomena of organized beings—not simply the phenomena of human physiology but the whole of vegetable and animal physiology, of which the human animal is but the highest and most interesting section. Few will maintain that clinical experience constitutes the pre-requisite to a correct understanding of the vegetable world.
Biology is the Science of Life. And first as to the definition of Life. Bichat, unconsciously determined by the ancient prejudice of living bodies being independent of—and antagonistic to—dead bodies (an error dwelt on in a preceding section) gave a definition, which has attained great celebrity, viz. : "Life is the sum of the functions by which death is resisted." Coleridge properly remarks, that he can discover in it " no other meaning than that life consists in being able to live ; ' and, indeed, if Bichat had only steadily considered the indispensable co-operation of the medium (or surrounding circumstances in which an organization is placed), with the organization itself,—if he had considered how a slight change in external conditions is sufficient to revive a dying animal or to destroy a living animal, he would never have propounded such a definition, for he would have seen that so far from organic bodies being independent of external circumstances they become more and more dependent on them as their organization becomes higher, so that organism and a medium are the two correlative ideas of life ; while inversely, it is in proportion as we descend the scale till we arrive at the most universal of all phenomena—those of gravitation, that the independence of a surrounding medium is manifested. Every change of temperature, every chemical combination, affects the organic body, whereas gravitation is in nowise disturbed by them. For the phenomena of attraction we only need simple atoms; for the phenomena of life we want the whole concourse of nature, and every variation in the medium is followed by a variation in the phenomena. If I insist on this dependence of the organism on the medium, it is because I find men in their reasonings constantly attaching themselves solely to the subjective, and forgetting the objective point of view—thinking only of the vital force, and forgetting the determinations of that force by external conditions.
Another definition, which has been a favourite with a large class, is this,—" Life is the result of organization." A truly metaphysical definition 1 Wherefore is life sup-posed to result from organization, rather than organization from the vital force, whatever it may be ?
In that very interesting posthumous essay by Cole-ridge, Hints towards the formation of a more comprehensive theory of life, (our pleasure in studying which is only abated by its being a shameless plagiarism from Schelling's Erster Entwurf, even to its very terminology), there is a definition which, though not wholly unobjectionable, gives a point of view the student will find extremely useful if thoroughly appreciated—and the definition is this, " Life is the principle of individuation," or that power which discloses itself from within, combining many qualities into one individual thing. To appreciate this, however, it must be studied in the commentary.
And I do not know where a more intelligible and comprehensive commentary, in brief space, can be found than in the following remarks on the definition :—" To make this definition intelligible, a few of the facts sought to be expressed by it must be specified,--facts exemplifying the contrast between low and high types of structure, and low and high degrees of vitality. Restricting our illustrations to the animal kingdom, and beginning where the vital attributes are most obscure, we find, for instance, in the genus Porifera, creatures consisting of nothing but amorphous semi-fluid jelly, supported upon horny fibres (sponge). This jelly possesses no sensitiveness, has no organs, absorbs nutriment from the water which permeates its mass, and if cut into two pieces lives on in each part as before. So that this " gelatinous film," as it has been called, shews little more individuality than a formless lump of inanimate matter ; for, like that, it possesses no distinction of parts, and, like that also, has no greater completeness than the pieces it is divided into. In the compound polyp, which stands next, and with which Coleridge commences, the progress towards individuality is manifest ; for there is now distinction of parts. To the originally uniform gelatinous mass with canals running through it, we have super-added, in the Alcyonidae, a number of digestive sacs, with accompanying mouths and tentacles. Here is, evidently, a partial segregation into individualities, a progress towards separateness. There is still complete community of nutrition; whilst each polyp has a certain independent sensitiveness and contractility. After complete separateness of organisms has been arrived at, the law is still seen in successive improvements of structure. By greater individuality of parts—by greater distinctness in the nature and functions of these, are all creatures possessing high vitality distinguished from inferior ones. Those Hydrœ just referred to, which are mere bags, with tentacles round the orifice, may be turned inside out with impunity. The stomach becomes skin, and the skin stomach. Here, then, is evidently no speciality of character ; the duties of stomach and skin are performed by one tissue, which is not yet individualized into two separate parts, adapted to two separate ends. The contrast between this state and that in which such a distinction exists, will sufficiently explain what is meant by individuation of organs. How clearly this individuation of organs is traceable throughout the whole range of animal life may be seen in the successive forms which the nervous system assumes. Thus, in the Acrita, a class comprehending all the genera above mentioned, `no nervous filaments or masses have been discovered; and the neurine or nervous matter is supposed to be diffused in a molecular condition through the body.'* In the class next above this, the Nematoneura, we find the first step towards individuation of the nervous system. `The nervous matter is distinctly aggregated into filaments. In the Homoyanyliata it is still further concentrated into a number of small equal-sized masses—ganglia. In the Heteroganyliata, some of these small masses are collected together into larger ones. Finally, in the Vertebrata, the greater part of the nervous centres are united to form a brain. And with the rest of the body there has simultaneously taken place just the same process of condensation into distinct systems muscular, respiratory, nutritive, excreting, absorbent, circulatory, &c., and of these again into separate parts, with special functions. The changes of vital manifestation associated with and consequent upon these changes of structure, have the same significance. To possess a greater variety of senses, of instincts, of powers, of qualities,—to be more complex in character and attributes, is to be more completely distinguishable from all other created things, or to exhibit a more marked individuality. For, manifestly, as there are some properties which all entities, organic and inorganic, have in common, namely, weight, mobility, inertia, &c.; and as there are additional properties which all organic entities have in common, namely, powers of growth and multiplication; and as there are yet higher properties which the organic entities have in common, namely, sight, hearing, &c., then those still higher organic entities possessing, characteristics not shared in by the rest, thereby differ from a larger number of entities than the rest, and differ in more points,that is, are more separate, more individual. Observe, again, that the greater power of self-preservation shown by beings of superior type may also be generalised under this same term—a " tendency to individualism." The lower the organism the more is it at the mercy of external circumstances. It is continually liable to be destroyed by the elements, by want of food, by enemies ; and eventually is so destroyed in nearly all diseases. That is, it lacks power to preserve its individuality; and loses this, either by returning to the form of inorganic matter, or by absorption into some other individuality. Conversely, there is strength, sagacity, swiftness (all of them indicative of superior structure), there is corresponding ability to maintain life—to prevent the individuality from being so easily dissolved ; and therefore the individuation is more complete.
"In man we see the highest manifestations of this tendency. By virtue of his complexity of structure, he is furthest removed from the inorganic world in which there is least individuality."
Although wandering from Comte by these remarks, I am still keeping within the necessities of an exposition of the Positive Philosophy; and the reader will now perhaps better appreciate what follows.
The only definition which seems to Comte capable of fulfilling all the multifarious conditions required, is the one proposed by De Blainville, viz.: Life is the twofold internal movement of composition and decomposition, at once general and continuous. " That luminous definition," he says, " seems to me to leave nothing to be desired, unless it be a more explicit indication of the two fundamental correlative conditions inseparable from a living being,—an organism and a medium. This, however, is but a secondary criticism. The definition presents the exact enunciation of the sole phenomenon rigorously common to the ensemble of living beings, considered in all their constituent parts, and in all their modes of vitality." At first sight, it may appear that this definition does not sufficiently respect the capital distinction so much insisted on by Bichat and his followers, between vegetative life and animal life, in other words, organic life and relative life, because it seems to refer entirely to the vegetative life. But, deeply considered, this very objection leads to a recognition of the real merit of this definition, by showing how it rests upon an exact appreciation of the biological hierarchy. For it is indisputable that, in the immense majority of organized beings, animal life is but a supplement, an additional series of phenomena, superposed on the fundamental organic life. And if, in the progressional ascent of being, we find what was at first the mere addition, become, at last, the most important, so that the vegetative life in Man seems destined only to sustain the animal life, his moral and intellectual attributes becoming the highest functions of his existence, that remarkable fact does not affect the order of biological study, but points to another fundamental science,—Sociology,—which takes its rise from Biology. Thus, with reference to the Science of Life, it remains true that the earliest forms are vegetative, and to them the study of animal life must be sub-ordinate; this is so in virtue of the greater generality of vegetative life, and also, according to the remark of Bichat, because the vegetative life is continuous, whereas the functions of animal life are intermittent.
Between these two forms of life there is indeed a capital distinction, viz. the one just alluded to of the intermittence of animal functions and the continuity of the vegetative functions, " and to complete this idea we must connect with it the double law of exercise which belongs only to animal life. The continuity of the vegetative functions excludes all satisfaction, even supposing the presence of sensitive nerves, because every pleasure requires for its existence something of the nature of comparison. It is in virtue of its intermittence that the two-fold animal property, passive and active, admits of the feeling derived from exercise, and creates the desire of repetition. In the second place, this repetition developes another attribute which cannot belong to continuous functions—the faculty of Habit, which constitutes the necessary basis of individual amelioration."