Problems of Life and Mind. Second series, George Henry Lewes [e book reading free TXT] 📗

do know. The organicist is ready to admit that much has still to be discovered; the vitalist, taking his stand upon this unknown, denies that what has been discovered is really important, and declares that the real agent is wholly unallied to it. How can he know this?

He does not know it; he assumes it; and the chief evidence he adduces is that the ordinary laws of inorganic matter are incapable of explaining the phenomena of organized matter; and that physical and chemical forces are controlled by vital force. I accept both these positions, stripping them, however, of their ambiguities. The laws of ordinary matter are clearly incompetent in the case of matter which is not ordinary, but specialized in organisms; and when we come to treat of Materialism we shall see how unscientific have been the hypotheses which disregard the distinction. The question of control is too interesting and important to be passed over here.

VITAL FORCE CONTROLLING PHYSICAL AND CHEMICAL FORCES.

16. The facts relied on by the vitalists are facts which every organicist will emphasize, though he will interpret them differently. When, for example, it is said that “Life resists the effect of mechanical friction,” and the proof adduced is the fact that the friction which will thin and wear away a dead body is actually the cause of the thickening of a living—the skin of a laborer’s hand being thickened by his labor; the explanation is not that Life, an extra-organic agent, “resists mechanical friction”—for the mechanical effect is not resisted (the skin is rubbed off the rower’s hand sooner than the wood is rubbed off the oar)—but that Life, i. e. organic activity repairs the waste of tissue.

17. Again, although many of the physical and chemical processes which invariably take place under the influences to which the substances are subjected out of the organism, will not take place at all, or will take place in different degrees, when the substances are in the organism, this is important as an argument against the notion of vital phenomena being deducible from physical and chemical laws, but is valueless as evidence in favor of an extra-organic agent. Let us glance at one or two striking examples.

18. No experimental inquirer can have failed to observe the often contradictory results which seemingly unimportant variations in the conditions bring about; no one can have failed to observe what are called chemical affinities wholly frustrated by vital conditions. Even the ordinary laws of Diffusion are not always followed in the organism. The Amœba, though semifluid, resists diffusion when alive; but when it dies it swells and bursts by osmosis. The exchange of gases does not take place in the tissues, precisely as in our retorts. The living muscle respires, that is, takes up oxygen and gives out carbonic acid, not on the principle of simple diffusion, but by two separable physiological processes. The carbonic acid is given out, even when there is no oxygen whatever present in the atmosphere, and its place may then be supplied by hydrogen; and this physiological process is so different from the physical process which goes on in the dead muscle (the result of putrefaction), that it has been proved by Ranke to go on when the temperature is so low that all putrefaction is arrested. The same experimenter finds4 that whereas living nerve will take up, by imbibition, 10 per cent of potash salts, it will not take up 1 per cent of soda salts, presented in equal concentration; and he points to the general fact that the absorption of inorganic substances does not take place according to the simple laws of diffusion, but that living tissues have special laws, the nerve, for instance, having a greater affinity for neutral potash salts than for neutral soda salts. Let me add, by way of anticipating the probable argument that may urge this in favor of Vital Principle which is lightly credited with the prescience of final causes, that so far from this “elective affinity” of the tissues being intelligent and always favorable, Ranke’s experiments unequivocally show that it is more active towards destructive, poisonous substances, than towards the reparative, alimentary substances; which is indeed consistent with the familiar experience that poisons are more readily absorbed than foods, when both are brought to the tissues. Thus it is well known that of all the salts the sulphate of copper is that which plants most readily absorb—and it kills them. The special affinities disappear as the vitality disappears, and dying plants absorb all salts equally.

19. The more the organism is studied, the more evident it will become that the simple laws of diffusion, as presented in anorganisms rarely if ever take effect in tissues; in other words, what is called Imbibition in Physics is the somewhat different process of Absorption in Physiology.5 The difference is notable in this capital fact, that whereas the physical diffusion of liquids and gases is determined by differences of density, the physiological absorption of liquids and gases is determined by the molecular organization of the tissue, which is perfectly indifferent to, and resists the entrance of, all substances incapable of entering into organic combination, either as aliment or poison. A curious example of the indifference of organized substances to some external influences and their reaction upon others, is the impossibility of provoking ciliary movement in an epithelial cell, during repose, by any electrical, mechanical, or chemical stimuli except potash and soda. Virchow discovered that a minute quantity of either of these, added to the water in which the cell floated, at once called forth the ciliary movements.

20. The true meaning of the resistance of Vitality to ordinary chemical affinity is, that the conditions involved in the phenomena of Vitality are not the conditions involved in the phenomena of Chemistry; in other words, that in the living organism the substances are placed under conditions different from those in which we observe these substances when their chemical affinities are displayed in anorganisms. But we need not go beyond the laboratory to see abundant examples of this so-called resistance to chemical affinity, when the conditions are altered. The decomposition of carbonates by tartaric acid is a chemical process which is wholly resisted if alcohol instead of water be the solvent employed. The union of sulphur with lead is said to be due to the affinity of the one for the other; but no one supposes this affinity to be irrespective of conditions, or that the union will take place when any one of these conditions is absent. If we fuse a compound of lead and iron in a crucible containing sulphur, we find it is the iron, and not the lead, which unites with the sulphur; yet we do not conclude that there is a Crucible Principle which frustrates chemical affinity and resists the union of sulphur and lead; we simply conclude that the presence of the iron is a condition which prevents the combination of the sulphur with the lead: not until all the iron has taken up its definite proportion of sulphur will the affinity of the lead come into play. This is but another illustration of the law that effects are processions of their causes, summations of the conditions of their existence. If the fire burns no hole in the teakettle so long as there is water to conduct the heat away, this is not due to any principle more mysterious than the presence of a readily conducting water.6

21. In accordance with the law of Causation just mentioned, which has been expounded in detail in our First Series (Vol. II. p. 335), the special combinations of Matter in organisms must present special phenomena. Therefore since the province of Biology is that of explaining organic phenomena by means of their organic conditions, it must be radically distinguished from the provinces of Physics and Chemistry, which treat not of organized but of inorganic matter. It is idle, it is worse, for it is misleading, to personify the organic conditions, known and inferred, in a Vital Principle; idle, because we might with equal propriety personify the conditions of crystallization in a Crystal Principle; misleading, because the artifice is quickly dropped out of sight, and the abstract term then becomes accepted as an entity, supposed to create or rule the phenomena it was invented to express.

22. Inquirers are but too apt to misconceive the value of Analysis, which is an artifice of Method indispensable to research, though needing the complementary rectification by Synthesis before a real explanation can be reached. Analysis decomposes the actual fact into ideal factors, separates the group into its components, and considers each of these, not as it exists in the group, in the reality, but as it exists when theoretically detached from the others. The oxygen and hydrogen into which water is decomposed did not exist as these gases in the water; the albumen and phosphate we extract from a nerve did not exist as isolated albumen and phosphate in the nerve, they were molecularly combined. In like manner the physical and chemical processes which may analytically be inferred in vital processes do not really take place in the same way as out of the organism. The real process is always a vital process, and must be explained by the synthesis of all the co-operant conditions. The laws of Physics and Chemistry formulate abstract expressions of phenomena, wherever and whenever these appear, without reference to the modes of production; and in this sense the movement of a limb is no less a case of Dynamics than the movement of a pulley—the decomposition of a tissue is a case of Chemistry no less than the decomposition of a carbonate; the electromotor phenomena observed in muscle are as purely physical as those observed in a telegraph. But when a biologist has to explain the movements of the limbs, or the decompositions of tissues, he has to deal with the phenomena and their modes of production, he has a particular group before him, and must leave out nothing that is characteristic of it. The movements of the pulley do not depend on Contractility and Sensibility, which in turn depend on Nutrition. The decomposition of the carbonate does not depend on conditions resembling those of a living tissue. Vaucanson’s duck was surprisingly like a living duck in many of its movements; but in none of its actions was there any real similarity to the actions of a bird, because the machine was unlike an organism in action. The antithesis of mechanism and organism will be treated of in § 78.

23. We conclude, then, that defining physical phenomena as the movements which take place without change of structure, and chemical phenomena as the movements with change of structure, although both classes may be said to take place in the organism, and to be the primary conditions on which organic phenomena depend, they do not embrace the whole of the conditions, nor are the sciences which formulate them capable of formulating either the special phenomena characteristic of organisms or their special modes of production. The biologist will employ chemical and physical analysis as an essential part of his method; but he will always rectify what is artificial in this procedure, by subordinating the laws of Physics and Chemistry to the laws of Biology revealed in the synthetic observation of the organism as a whole. The rectification, here insisted on, will be recognized as peculiarly urgent in Psychology, which has greatly suffered from the misdirection of Analysis.

24. No one will misunderstand this specialization of Biology to mean a separation of Life from the series of objective phenomena, and the introduction of a new entity; the specialization points to a Mode of Existence. All classifications are artifices, but they have their