Part 16

Such a theory is open to very serious criticism from both the scientific and the philosophical side. But before we pass to that criticism let us turn aside to examine some of the other aspects under which the Proteus of Vitalism presents himself.

Thus the modern physiologist Bunge, while owning that it would be a lack of intelligence to expect to make with our senses discoveries in living nature of a different order to those revealed to us in inorganic nature, yet insists that we must transfer to the objects of our sensory perception, to the organs, to the tissue elements, and to every minute cell, something which we have acquired from our own consciousness, something, that is to say, which is not motion, and is not in space, but is in time only.

The essence of vitalism, so Bunge would have it, lies in starting from what we know, the internal world, to explain what we do not know, the external world. We can only remark that this position appears to rest upon an epistemological confusion, for Bunge has evidently failed to distinguish between the idealism which teaches that the world of nature, including our own bodies, only exists in so far as it is an object of knowledge, that reality is ultimately ideal, and the ‘animism’ which, as we have seen, gives every object, at least every living object, in nature a directive consciousness of its own. The former does not lie immediately within the scope of the present inquiry; the latter we shall have occasion to discuss again.

How far the tenets of animism are to be attributed to Johannes Müller is not very clear. For while Müller maintained that an organism is due to an idea which regulates its structure, is the cause of its harmony, and is in action in the organism itself, exerting on it a formative power, yet he held that the process was unconscious. Müller indeed distinguished explicitly between the vital and the mental or conscious principle, for in the operations of the former the manifestation of design is the result of necessity, not of choice. At the same time the two resemble one another in being homogeneous, in existing throughout the mass of the organism which they animate, and in being divided together with the organism (as in regeneration) without suffering any diminution or change of their powers.

In this conception of the unconscious idea there may possibly be some confusion between the formal and the final cause, between the idea of the end to be realized, present at the beginning in the mind of the artificer, and the end itself. The former is animism: the latter is sound enough as metaphysics, but is not science at all.

There is still another school of vitalists which, while not going so far as to commit itself to a belief in a ‘psychoid’, yet proclaims in no uncertain voice the autonomy of the organism, and not content with the assertion that at present we have not succeeded in reducing the activities of the organism to chemical, physical, and mechanical processes, maintains the utter futility of such endeavour, and pronounces over the hidden mysteries of life an eternal Ignorabimus.

Some such view as this we must, I think, attribute to Dr. Haldane. ‘In biology’, he says, ‘the phenomena which are or ought to be observed from the very beginning are not physical and chemical phenomena as self-existent events, but these phenomena as expressions of the activity of living organisms. It is the living organism, and not the physical phenomenon, which is the reality for biology.’ His belief in organic autonomy is based on the physiology of metabolism, secretion and absorption, the circulation of the blood, and the nervous system. Thus in discussing the blood, after pointing to the constancy in its volume and composition, he proceeds: ‘Neither starvation nor ingestion of food and drink materially affect it: liquid injected into it is got rid of with remarkable rapidity; and any loss of blood by bleeding is soon replaced. This vital metabolism of the circulatory system is doubtless due chiefly to the activity of its lining endothelium, which most certainly does not play the mere mechanical part which has often been attributed to it. The other so-called “mechanisms” can likewise be shown to have all the characteristics of the living body, inasmuch as they actively maintain their structure, just as the organism as a whole does so. There is thus no warrant for calling them mechanisms, and thus ignoring what is one of their essential characteristics.’ In passages such as these we seem to catch an echo of Müller’s unconscious idea, and again we ask ourselves, Are we dealing with a final or a formal cause? Indeed, Dr. Haldane insists that his ground conception is teleological.

There is still one other vitalistic theory to which we must allude, although its interest is now merely historical. This is the belief in a special vital material, unlike the material of which lifeless bodies are composed, and endowed with a special vital force, different from but co-ordinate with the forces of mechanics and physics.

In his Histoire Générale des Animaux Buffon, after referring to the obvious peculiarities of animals and vegetables--that their actions are directed to an end, the conservation of a durable species--proceeds to elaborate a thesis in which it is held that they are composed of organic germs, and that germs of the same kind are distributed throughout nature, lifeless as well as living. When an animal or plant dies, its body is dissolved into these germs, which are then scattered abroad; when it assimilates, it is by separating these ubiquitous particles from the brute inorganic portion of the food. The former is utilized for its own growth, the latter it gets rid of by evacuation and excretion. Lifeless matter is therefore never converted into living material.

Another advocate of the doctrine of a vital force, a property of the tissues of the body, and at perpetual war with those inorganic forms which tend to their destruction, was the physiologist Bichat, Such a conception as this could not of course survive the rise of modern chemistry. Its death-knell was sounded when Lavoisier and Laplace showed that the bodies of organisms were composed of the same elements as are found in inanimate nature, and it has long since passed into the limbo of discredited speculations.

Apart from this, vitalistic theories would appear to be in the main of two kinds.

First, there is the metaphysical vitalism which tells us we can never explain the living in terms of the lifeless, insists on the permanent separation of the sciences of biology on the one hand from chemistry and physics on the other, and preaches the autonomy of the organism without venturing to tell us in what that autonomy consists.

Secondly, there is the psychological theory of animism which posits an autonomous psychical entity to preside over the chemical and mechanical operations of the body, whether already formed or in process of development, and to direct them towards its own ends, the conservation and reproduction of that body’s specific form.

A third party, halting between two opinions, suggests an unconscious idea, without, however, clearly explaining whether this is to be taken in a metaphysical or a psychological sense. Frankly opposed to vitalism in all its forms is the conception of the living body as a mechanism. This has also an honourable ancestry behind it. How far the biology of Aristotle is to be looked upon as mechanistic we shall presently have to inquire, but in Galen the soul is certainly material, or quasi-material, as we have already observed. It is, however, in the physiology of Descartes that mechanism first appears unmistakably in its modern guise.

For Descartes the body is simply an earthly machine. The nerves are tubes up which--in sensation--the animal spirits flow to the brain only to be reflected (whence our term reflex action) down other tubes to the muscles.

‘All the functions of the body’, he tells us, ‘follow naturally from the sole disposition of its organs, just in the same way that the movements of a clock or other self-acting machine or automaton follow from the arrangement of its weights and wheels. So that there is no reason on account of its functions to conceive that there exists in the body any soul, whether vegetative or sensitive, or any principle of movement other than the blood and its animal spirits agitated by the heat of the fire which burns continually in the heart and does not differ in nature from any of the other fires which are met with in inanimate bodies.’

The rational soul, the soul which thinks, that is, understands, wishes, imagines, remembers, and feels, is not material. Yet it always acts through the machine, though that machine can go on perfectly well without the soul. ‘When the body has all its organs properly arranged for a particular movement it has no need of the soul to carry them out. All movements, even those which we call voluntary, depend principally on the same disposition of the organs. One and the same cause renders the dead body unfit to produce the movements and leads the soul to quit the body.’

The biology of Descartes appears to have been accepted by contemporary physiologists like van Helmont and Borelli, and certainly commended itself to another philosopher of eminence, Leibnitz. Like Descartes, Leibnitz also affirms that the body is a machine or natural automaton; unlike Descartes, however, he refuses to believe that the mind directs the machine in any way. Rather there is a complete series of psychical parallel to a complete series of physical events, and between the two a pre-established harmony.

Although the details of Cartesian physiology have long since been exploded, yet the mechanical principle which that philosophy enunciated so clearly has persisted and has indeed proved to be the rock on which modern physiological science has been built. For, when once the chemists had discovered animal and plant structure to be composed of elements found in lifeless bodies, and had proved that compounds found only in the organism could yet be synthesized in vitro, there was no longer any reason why the properties of the compounds should be considered as of a different order to the properties of their component elements. A method applicable to one was applicable to the other, and as Claude Bernard has put it, mechanical, physical, and chemical forces are the only effective agents in the living body, and they are the only agencies of which the physiologist has to take account.

The substances of which the living body is made up are no doubt extremely complex, yet none the less--to quote a more recent writer, Verworn--‘physiology is in the last resort the chemistry of the proteids’. This is the principle that has now for nearly a century guided and stimulated research into the functions of the organism: to this principle physiologists, too numerous to name, have not been ashamed to subscribe: under its banner some of the proudest triumphs of the science have been won. Yet it is precisely this which modern or neo-vitalism has challenged and asks us to relinquish in favour of a theory of psychoids or a pseudo-metaphysical view of life.

The vitalistic position may be assailed from two points, the scientific and the philosophical.

In the first place the vitalist asserts that mechanism is inadequate to explain the phenomena of metabolism, of transmission of nervous stimuli, or of development. It is upon the last of these that Driesch lays special stress.

He has urged, as we have seen, that although a mechanical explanation might be given (such an explanation has indeed been put forward by himself) of the specific differentiation of the organism by supposing the first-formed elementary organs, developed out of the substances given in the initial structure of the germ, to act and react upon one another in accordance with a certain harmony, provided for by the same structure; yet a mechanism which can be subdivided ad libitum or almost ad libitum, and each part of which will still give rise to a complete organism, is not to be conceived. The answer to this objection has, however, been supplied by the experiments of Driesch himself and of many others. For though it is true that each of the first two, four, eight, or even in some cases each of the first sixteen cells into which the fertilized ovum becomes segmented, can, when separated from its fellows, give rise to a complete organism, yet in all cases there comes a time when the parts cease to be totipotent and produce not whole but partial structures.

This invariable restriction of potentialities, which occurs earlier in some cases than in others, and is not due to mere deficiency of substance, is not hard to account for.

Those substances on the presence of which in the ovum, as experiment has taught us, the formation of the elementary organs of the embryo or larva depends, are arranged in different cases in different ways: and they certainly may be, and very frequently are, so distributed that while each of the first four cells contains a like quantity of each of these specific substances, arranged in it exactly as they were in the whole ovum, the next division will sunder these materials in such a way that of the resulting eight blastomeres four will have more of one of the primary egg-substances, less of another; the amounts apportioned to the other four being in just the inverse ratio of this: and the result will be a difference in the fate of the cells when they are isolated from one another. In those of the one group the proportions of the organs developed out of these substances will not be the same as they are in the other. This is precisely the result which experiment has revealed; it is exactly this result which Driesch has ignored, or rather attempted to explain away.

It is evident, then, that to some extent the parts of this mechanism are interchangeable, that it can be subdivided, and that each part, brought now under new conditions, will still possess the potentialities of the whole, just as such a mechanism as a rocket, out of which, under the appropriate stimulus, a certain pattern of stars is developed, might be subdivided into two or more rockets of half size or less. There is, however, a limit to this interchangeability, while if the subdivision be carried beyond a certain point the totipotence of the parts is lost.

If the number of these organ-forming substances given in the germ were very large, as large, let us suppose, as the total number of separately inheritable characters, it might indeed be difficult to imagine a mechanism divisible into even two totipotent parts. But from the need for this assumption we are saved by the second part of Driesch’s own Analytische Theorie, which accounts for subsequent processes of differentiation by attributing the production of new parts to the mutual interactions of those that are the first to appear. For this also experimental evidence, though meagre, is not lacking, while a close parallel is found in the dependence of certain bodily functions upon substances--the hormones of Professor Starling--secreted by other organs.

In the second place the vitalist maintains that the processes of metabolism defy, nay more, always will defy, chemical and physical analysis. The first part of this statement may be a true description of the knowledge of to-day, but the existence in the living body of the same elements as are met with elsewhere, the synthesis of complex organic substances, the establishment of the equivalence of the energy which leaves the body as mechanical work or heat to that which enters it in chemical form in the food, should surely make us hesitate before abandoning all hope of attaining to a chemistry of life.