Among the vitalists of to-day, one of the most frequently cited, perhaps, except Driesch the most frequently cited, is G. Wolff, a _Privatdozent_, formerly at Würzburg, now at Basle. He has only published short lectures and essays, and these deal not so much with the mechanical theory as with Darwinism.(86) But in these writings his main argument is that of his concluding chapter: the spontaneous adaptiveness of the organism, which nullifies all contingent theories to explain the purposiveness in ontogeny and phylogeny. And in his lecture, “Mechanismus und Vitalismus,”(87) in which he directs his attention especially to criticising Bütschli’s defence of mechanism, the only problem to which prominence is given is the one with which we are here concerned. In spite of their brevity, these writings have given rise to much controversy, because what is peculiar to the two standpoints is described with precision, and the problem is clearly defined. His criticism had its starting-point in, and received a special impulse from an empirical proof, due to a very happy experiment of his own, of the marvellous regenerative capacity, and the inherent purposive activity of the living organism. He succeeded in proving that if the lens of the eye of the newt be excised, it may be regrown. The importance of this fact is greatly increased if we trace out in detail the various impossible rival mechanical interpretations which have grown up around this interesting case. As Driesch says, “It is not a restoration starting from the wound, it is a substitution starting from a different place.”
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 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.