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.

Kassowitz83 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