The Organism As a Whole, From a Physicochemical Viewpoint

CHAPTER I. Introductory Remarks

INTRODUCTORY REMARKS

1. The physical researches of the last ten years have put the atomistic theory of matter and electricity on a definite and in all probability permanent basis. We know the exact number of molecules in a given mass of any substance whose molecular weight is known to us, and we know the exact charge of a single electron. This permits us to state as the ultimate aim of the physical sciences the visualization of all phenomena in terms of groupings and displacements of ultimate particles, and since there is no discontinuity between the matter constituting the living and non-living world the goal of biology can be expressed in the same way.

This idea has more or less consciously prevailed for some time in the explanation of the single processes occurring in the animal body or in the explanation of the functions of the individual organs. Nobody, not even a scientific vitalist, would think of treating the process of digestion, metabolism, production of heat, and electricity or even secretion or muscular contraction in any other than a purely chemical or physicochemical way; nor would anybody think of explaining the functions of the eye or the ear from any other standpoint than that of physics.

When the actions of the organism as a whole are concerned, we find a totally different situation. The same physiologists who in the explanation of the individual processes would follow the strictly physicochemical viewpoint and method would consider the reactions of the organism as a whole as the expression of non-physical agencies. Thus Claude Bernard, who in the investigation of the individual life processes was a strict mechanist, declares that the making of a harmonious organism from the egg cannot be explained on a mechanistic basis but only on the assumption of a “directive force.” Bernard assumes, as Bichat and others had done before him, that there are two opposite processes going on in the living organism: (1) the phenomena of vital creation or organizing synthesis; (2) the phenomena of death or organic destruction. It is only the destructive processes which give rise to the physical manifestations by which we judge life, such as respiration and circulation or the activity of glands, and so on. The work of creation takes place unseen by us in the egg when the embryo or organism is formed. This vital creation occurs always according to a definite plan, and in the opinion of Bernard it is impossible to account for this plan on a purely physicochemical basis.

Bernard C., Leçons sur les Phénomènes de la Vie. Paris, 1885, i., 22-64.

There is so to speak a pre-established design of each being and of each organ of such a kind that each phenomenon by itself depends upon the general forces of nature, but when taken in connection with the others it seems directed by some invisible guide on the road it follows and led to the place it occupies....

We admit that the life phenomena are attached to physicochemical manifestations, but it is true that the essential is not explained thereby; for no fortuitous coming together of physicochemical phenomena constructs each organism after a plan and a fixed design (which are foreseen in advance) and arouses the admirable subordination and harmonious agreement of the acts of life....

We can only know the material conditions and not the intimate nature of life phenomena. We have therefore only to deal with matter and not with the first causes or the vital force derived therefrom. These causes are inaccessible to us, and if we believe anything else we commit an error and become the dupes of metaphors and take figurative language as real.... Determinism can never be but physicochemical determinism. The vital force and life belong to the metaphysical world.

In other words, Bernard thinks it his task to account for individual life phenomena on a purely physicochemical basis--but the harmonious character of the organism as a whole is in his opinion not produced by the same forces and he considers it impossible and hopeless to investigate the “design.” This attitude of Bernard would be incomprehensible were it not for the fact that, when he made these statements, the phenomena of specificity, the physiology of development and regeneration, the Mendelian laws of heredity, the animal tropisms and their bearing on the theory of adaptation were unknown.

This explanation of Bernard’s attitude is apparently contradicted by the fact that Driesch and v. Uexküll, both brilliant biologists, occupy today a standpoint not very different from that of Claude Bernard. Driesch assumes that there is an Aristotelian “entelechy” acting as directing guide in each organism; and v. Uexküll suggests a kind of Platonic “idea” as a peculiar characteristic of life which accounts for the purposeful character of the organism.

v. Uexküll supposes as did Claude Bernard and as does Driesch that in an organism or an egg the ultimate processes are purely physicochemical. In an egg these processes are guided into definite parts of the future embryo by the Mendelian factors of heredity--the so-called genes. These genes he compares to the foremen for the different types of work to be done in a building. But there must be something that makes of the work of the single genes a harmonious whole, and for this purpose he assumes the existence of “supergenes.” v. Uexküll’s ideas concerning the nature of a Mendelian factor and of the “supergenes” are expressed in metaphorical terms and the assumption of the “supergenes” begs the question. The writer is under the impression that this author was led to his views by the belief that the egg is entirely undifferentiated. But the unfertilized egg is not homogeneous, on the contrary, it has a simple but definite physicochemical structure which suffices to determine the first steps in the differentiation of the organism. Of course, if we suppose as do v. Uexküll and Driesch that the egg has no structure, the development of structure becomes a difficult problem--but this is not the real situation.

Driesch, H., The Science and Philosophy of the Organism. 2 vols. The Gifford Lectures, 1907 and 1908.

v. Uexküll, J., Bausteine zu einer biologischen Weltanschauung. München, 1913.

v. Uexküll, J., Bausteine zu einer biologischen Weltanschauung. München, 1913, p. 216.

2. Claude Bernard does not mention the possibility of explaining the harmony or apparent design in the organism on the basis of the theory of evolution, he simply considers the problem as outside of biology. It was probably clear to him as it must be to everyone with an adequate training in physics that natural selection does not explain the origin of variation. Driesch and v. Uexküll consider the Darwinian theory a failure. We may admit that the theory of a formation of new species by the cumulative effect of aimless fluctuating variations is not tenable because fluctuating variation is not hereditary; but this would only demand a slight change in the theory; namely a replacement of the influence of fluctuating variation by that of equally aimless mutations. With this slight modification which is proposed by de Vries, Darwin’s theory still serves the purpose of explaining how without any pre-established plan only purposeful and harmonious organisms should have survived. It must be said, however, that any theory of life phenomena must be based on our knowledge of the physicochemical constitution of living matter, and neither Darwin nor Lamarck was concerned with this. Moreover, we cannot consider any theory of evolution as proved unless it permits us to transform at desire one species into another, and this has not yet been accomplished.

de Vries, H., Die Mutationstheorie. Leipzig, 1901.

It may be of some interest to point out that we do not need to make any definite assumption concerning the mechanism of evolution and that we may yet be able to account for the fact that the surviving organisms are to all appearances harmonious. The writer pointed out that of all the 100,000,000 conceivable crosses of teleost fish (many of which are possible) not many more than 10,000, i. e., about one-hundredth of one per cent., are able to live and propagate. Those that live and develop are free from the grosser type of disharmonies, the rest are doomed on account of a gross lack of harmony of the parts. These latter we never see and this gives us the erroneous conception that harmony or “design” is a general character of living matter. If anybody wishes to call the non-viability of 99-99/100 per cent. of possible teleosts a process of weeding out by “natural selection” we shall raise no objection, but only wish to point out that our way of explaining the lack of design in living nature would be valid even if there were no theory of evolution or if there had never been any evolution.

3. v. Uexküll is perfectly right in connecting the problem of design in an organism with Mendelian heredity. The work on Mendelian heredity has shown that an extremely large number of independently transmissible Mendelian factors help to shape the individual. It is not yet proven that the organism is nothing but a mosaic of Mendelian factors, but no writer can be blamed for considering such a possibility. If we assume that the organism is nothing but a mosaic of Mendelian characters it is difficult indeed to understand how they can force each other into a harmonious whole; even if we make ample allowance for the law of chance and the corresponding wastefulness in the world of the living. But it is doubtful whether this idea of the rôle of Mendelian factors is correct. The facts of experimental embryology strongly indicate the possibility that the cytoplasm of the egg is the future embryo (in the rough) and that the Mendelian factors only impress the individual (and variety) characters upon this rough block. This idea is supported by the fact that the first development--in the sea urchin to the gastrula stage inclusive--is independent of the nucleus, which is the bearer of the Mendelian factors. Not before the skeleton or mesenchyme is formed in the sea urchin egg is the influence of the nucleus noticeable. This has been shown in the experiments of Boveri in which an enucleated fragment of an egg was fertilized with a spermatozoön of a foreign species. If this is generally true, it is conceivable that the generic and possibly also the species characters of organisms are determined by the cytoplasm of the egg and not by the Mendelian factors.

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