Along with Virchow, we must name another of the older generation, the physiologist William Preyer, who combated “vitalism,” “dualism,” and “mechanism” with equal vehemence, and issued a manifesto, already somewhat solemn and official, against “vital force.” And yet he must undoubtedly be regarded as a vitalist by mechanists and vitalists alike.[79] He is more definite than Virchow, for he does not content himself with general statements as to the “origin” of vital force, and of the “swinging over” of the merely mechanical energies into the domain of the vital, but holds decidedly to the proposition omne vivum e vivo. He therefore maintains that life has always existed in the cosmos, and entirely rejects spontaneous generation.
The fallacy, he says, of the mechanistic claims was due to the increasing number of physical explanations of isolated vital phenomena, and of imitations of the chemical products of organic metabolism. A wrong conclusion was drawn from these. “Any one who hopes to deduce from the chemical and physical properties of the fertilised egg the necessity that an animal, tormented by hunger and love must, after a [pg 240] certain time, arise therefrom, has a pathetic resemblance to the miserable manufacturers of homunculi.” Life is one of the underivable and inexplicable fundamental functions of universal being. From all eternity life has only been produced from life.
As Preyer accepts the Kant-Laplace theory of the origin of our earth from the sun, he reaches ideas which have points of contact with the “cosmo-organic” ideas of Fechner. Life was present even when the earth was a fiery fluid sphere, and was possibly more general and more abundant then than it is now. And life as we know it may only be a smaller and isolated expression of that more general life.[80]
Among the younger generation of specialists, those most often quoted as opponents of the mechanical theory are probably Bunge, Rindfleisch, Kerner von Marilaun, Neumeister and Wolff. A special group among them, not very easy to classify, may be called the Tectonists. Associated with them is Reinke's “Theory of Dominants.” Driesch started from their ranks, and is a most interesting example of consistent development from a recognition of the impossibilities of the mechanistic position to an individually thought-out vitalistic theory. Hertwig, too, takes a very definite position of his own in regard to these matters. Perhaps the most original contribution in the whole field is Albrecht's “Theory of Different Modes of Regarding Things.” We may close the list with the name of K. C. Schneider, who has carried these modern ideas on into metaphysical speculation. Several others might be mentioned along with and connecting these representative names.[81]
The Position Of Bunge and Other Physiologists.
For a long time one of the most prominent figures in the controversy was Prof. G. Bunge, of Basle, who was one of the first modern physiologists to champion vitalism, and who has tried to show by analogies and illustrations what is necessarily implied in vital activity.[82] The mechanical reduction of vital phenomena to physico-chemical forces, he says, is impossible, and becomes more and more so as our knowledge deepens. He brings forward a series of convincing examples of the way in which apparent mechanical explanations have broken down. The absorption of the chyle through the walls of the intestine seemed to be a mechanically intelligible process [pg 243] of osmosis and diffusion. But in reality it proves to be rather a process of selection on the part of the epithelial cells of the intestine, analogous to the selection and rejection exercised elsewhere by unicellular organisms. In the same way the epithelial cells of the mammary glands “select” the suitable substances from the blood. It is impossible to explain in a mechanical way the power which directs the innumerable different chemical and physical processes within the organism, whether they be the bewilderingly purposeful reactions in the individual life of the cell, which seem to point to psychic processes within the plasm, or the riddles of development and of inheritance in particular; for how can a spermatozoon, so small that 500 millions can lie on a cubic line, be the bearer of all the peculiarities of the father to the son?
In Lecture III. Bunge defines his attitude towards the law of the conservation of energy. In so doing he unconsciously follows the lines laid down by Descartes. All processes of movement and all functions exhibited by the living substance are the results of the accumulated potential energies, and the sums of work done and energy utilised remain the same. But the liberation and the direction of these energies is a factor by itself, which neither increases nor diminishes the sum of energies. “Occasiones” and “causæ” are brought into the field once more. The energies effect the phenomena, but they require “occasiones” to liberate them—thus a stone may fall to the ground by virtue of the [pg 244] potential energies stored in it at the time of its suspension, but it cannot fall until the thread by which it hangs has been cut. The function of the “occasio” itself is something quite outside of and without relation to the effect caused; it is a matter of indifference whether the thread be cut gently through with a razor or shot in two with a cannon ball.
Kassowitz[83] is an instructive example of how much the force of criticism has been recognised even by those occupying a convinced mechanical point of view. He subjects all the different theories which attempt to explain the chief vital phenomena in mechanical terms to a long and exhaustive examination. The theories of the organism as a thermodynamic engine, osmotic theories, theories of ferments, interpretations in terms of electro-dynamics and molecular-physics—are all examined (chap. iv.); and the failure of all these hypotheses, notwithstanding the enormous amount of ingenuity expended in their construction, is summed up in an emphatic “Ignoramus.” “The failure is a striking one,” and it is frankly admitted that, in strong contrast to the earlier mood of confident hope, there now prevails a mood of resignation in regard to the mechanical-experimental investigation of the living organism, and that even specialists of the first rank are finding that they have to reckon again seriously with vital force. This breakdown and these admissions do not exactly tend to prejudice us in favour of the [pg 245] author's own attempt to substantiate new mechanical theories.
In the comprehensive text-book of physiological chemistry by R. Neumeister, the mechanical standpoint seemed to be adhered to as the ideal. But the same writer forsakes it entirely, and disputes it energetically in his most recent work, “Betrachtungen über das Wesen der Lebenserscheinungen”[84] (“Considerations as to the Nature of Vital Phenomena”). He passes over all the larger problems, such as those of development, inheritance, regeneration, and confines himself in the main to the physiological functions of protoplasm, especially to those of the absorption of food and metabolism. And he shows, by means of illustrations, in part Bunge's, in part his own, and in close sympathy with Wundt's views, that even these vital phenomena cannot possibly be explained in terms of chemical affinity, physical osmosis, and the like. In processes of selection (such as, for instance, the excretion of urea and the retention of sugar in the blood), the “aim is obvious, but the causes cannot be recognised.” Psychical processes play a certain part in the functions of protoplasm in the form of qualitative and quantitative sensitiveness. All the mechanical processes in living organisms are initiated and directed by psychical processes. Physical, chemical and mechanical laws are perfectly valid, but they are not absolutely dominant. Living matter is to be defined as “a unique chemical [pg 246] system, the molecules of which, by their peculiar reciprocal action, give rise to psychical and material processes in such a way that the processes of the one kind are always causally conditioned and started by those of the other kind.” The psychical phenomena he regards as transcendental, supernatural, “mystical,” yet unquestionably also subject to a strict causal nexus, although the causality must remain for ever concealed. Starting from this basis, he analyses and rejects the explanations which have been offered in terms of the analogy of ferments, enzymes, or catalytic processes. In particular, he disputes Ostwald's “Energismus” and Verworn's Biogen hypothesis.[85]