It might have been expected that in the domain of plant-biology, if anywhere, the mechanistic standpoint would have been the prevailing one. For it is almost a matter of course to regard plants as devoid of sensation or “psychical” life, and as mechanical systems, chemical laboratories, and reflex mechanisms, and this way of regarding them has been made easy by the very marked uniformity and lack of spontaneity in their vital processes as compared with those of animals. But it is not the case that mechanical theories have here prevailed. The opposition to them is just as great here as elsewhere, and from the days of Wigand onwards it has been almost continuously sustained.88 Very characteristic is [pg 249] Pfeffer's “Pflanzen-Physiologie” (1897), which is written professedly from the mechanist point of view. “Vitalism,” according to this authority, is to be rejected, but instead of “vital force” he offers us “given properties,” and the alleged machine-like collocations of the most minute elements. In regard, for instance, to the riddle of development and morphogenesis, we must simply accept it as a “given property,” that the acorn grows in an oak and nothing else. The chemical explanation of the vital functions of protoplasm is also to be rejected; as a shattered watch is no longer a watch though it remains chemically the same, so it is with protoplasm. The available chemical knowledge of the substances of which protoplasm is made up is insufficient to render the vital processes intelligible. Here, as everywhere else, we have to reckon with ultimate “properties (entities), which we neither can, nor desire to analyse further.” “The human mind is no more capable of forming a conception of the ultimate cause of things than of eternity.” If all the views here indicated were followed out to their logical conclusions, they would hinder rather than further the process of reduction to terms of physico-chemical sequences.
Kerner von Marilaun in his “Pflanzenleben” deliberately takes up a thorough-going vitalist position, and on this point as well as on many others he opposed the current theory of the school (Darwinism). It is true, he admits, that many of the phenomena in plants [pg 250] can be explained in purely mechanical terms, but they are only those which may occur also in non-living structures. The specific expressions of life cannot be explained in this way. He shows this more fully in regard to the most fundamental of all the vital processes in the plant-body—the breaking up of carbonic acid gas by the chlorophyll to obtain the carbon which is the fundamental element in all living organisms. We know the requisite conditions: the supply of raw material, and the sunlight from which the energy is derived. But how the chlorophyll makes use of these to effect the breaking up, and how it starts the subsequent syntheses of the carbon into the most complex organic compounds remains a mystery. And so on upwards through all the strictly vital phenomena.
Wiesner's89 view of things is essentially similar. He gives a very impressive picture of the mystery of the chemistry of the plant, showing how small is the number of food-stuffs and raw materials in comparison to the thousands of highly complex chemical substances which the plant produces, and how much work there is involved in de-oxydising the food and in forming syntheses. He, too, refuses, as usual, to postulate “vital force.” Yet to speak of “the fundamental peculiarities of the living matter inherent in the organism” and to admit that plants are “irritable,” “heliotropic,” “geotropic,” &c., amounts to much the same thing as postulating vital [pg 251] force; that is to say, to a mere naming of the specific problem of life without explaining it. The author himself admits this when he says in another place: “If I compare organisms with inorganic systems, I find that the progress of our knowledge is continually enlarging the gulf which separates the one from the other!”
These anti-mechanical tendencies show themselves most emphatically in the work of Fr. Ludwig.90 In his concluding chapter, after a discussion of the theories of Darwin, NÄgeli, and Weismann, he postulates, for variation, heredity, and species-formation in particular, “forces other than physico-chemical,” “let us call them frankly psychical.”
It is instructive to see how these “vitalistic” views crop up even in studies of detail and of the microscopically small, as for instance in E. Crato's “BeitrÄge zur Anatomie und Physiologie des Elementar-organismus.” How the living organism contains within itself what is in its turn living, down into ever smaller detail, (amoeboid movements of certain plastines, physodes,) how incomparable the living organism is with a “machine,” to which its libellers are so fond of likening it, how it builds itself up, steers, and stokes itself, how it produces with “playful ease” the most marvellous and graceful forms, makes combinations and breaks them up, how analogous its whole activity is to “being able” and “willing,” all this is clearly brought out.91
[pg 252] A very fresh and lucid presentation of the whole case is given by Borodin, Professor of Botany in St. Petersburg, in his essay, “Protoplasm and Vital Force.”92 He sharply castigates the one-sidedness and impetuosity of the mechanical theory, as in Haeckel's discovery of Bathybius and of non-nucleated bacteria. The latter [pg 253] are problematical, and the former has been proved an illusion. To penetrate farther into the processes of life is simply to become aware of an ever-deepening series of riddles. There is no such thing as “protoplasm,” or “living proteid,” or indeed any unified, simple “living matter” whatever. Artificial “oil-emulsion amoebÆ”93 bear the same relation to living ones that Vaucanson's mechanical duck bears to a real one; that is, none at all. Our “protoplasm” is as mystical as the old “vital force,” and both are only camping-grounds for our ignorance. Neither the mechanical nor the atomic theory were the results of exact investigations; they were borrowed from philosophy. We do indeed investigate the typically vital process of irritability by physical methods. But the response made by the organism to physical coercion may be called a mockery of physics. The mechanists help themselves out with crude analogies from the mechanical, conceal the problem with the name “irritability,” and thus get rid of the greatest marvels. If vital force itself were to call out from its cells, “Here I am,” they would probably see in it only a remarkable case of “irritability.” Mechanism is no more positive knowledge than vitalism is; it is only the dogmatic faith of the majority of present-day naturalists.
