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,[1] 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.

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[2] and v. Uexküll,[3] 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.”[4] 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.