DEVELOPMENT OF PLANT PHYSIOLOGY 119 



a specific " principle " in the life of organisms could not be better ex- 

 pressed; and the reference to " individuality " is a pregnant thought 

 with regard to the enharmony evident in every living form. 



It seemed as if the last traces of teleology would have been effaced 

 from biology by Darwin's theory of selection. No one has expressed 

 this more clearly than Schleiden, who, always a tireless opponent of 

 every teleological conception, speaking concerning Darwin's doctrine, 

 cried out in triumph at the close of his activity as a student: "Tele- 

 ology belongs no more to science, but has its place now only in mere 

 talk." 1 His opposition to teleology started from a one-sided, pedantic 

 philosophy, but his disputatious arguments gained great weight with 

 the majority of the botanists of his time, and his influence in this 

 direction has remained, sporadically to be sure, up till our time. Most 

 of the botanists of his time were so overawed by him that scarcely 

 one of them dared to speak of the purposes of organs or of purpose- 

 ful arrangements in organisms and so on. And this, as a result, 

 worked a desolation in morphology, and made more difficult its union 

 with physiology. 



In this also, however, Schleiden by his hypercriticism overshot the 

 mark. For it was just this great scientific movement, which Darwin 

 set up through the rehabilitation of the doctrine of descent, that of 

 necessity placed teleology in its right place. And this teleology, en- 

 riched by an immense number of facts, contributed materially to the 

 advance of the biological sciences. It has also brought it about that 

 eminent and scientifically educated philosophers, such as Wundt, 

 enforced again the recognition of teleology together with causal- 

 ity. In this the reaction of natural science upon philosophy is only 

 slightly indicated. It extended, however, much further, for the 

 rehabilitation of the theory of knowledge is the result of the advance- 

 ment of natural science; and the cooperation of eminent scientists, 

 such as Boltzmann, Mach, Ostwald, Reinke, and other also scienti- 

 fically trained philosophers, shows, in the building up of the theory 

 of perception, how science entered this field to its advancement. 



That which in the teleological conception concerns transcend- 

 entalism we leave to the specialists in the theory of knowledge. 

 We stand on the ground of experience, and permit of metaphysics, 

 as we have said above, only as a source of helpful ideas, which, how- 

 ever, may be permitted only when they do not negate experience, and 

 only so long as they prove themselves useful in opening up to us 

 new directions for inductive research. If through this kind of scien- 

 tific operation the clear area within which we move appears to be 

 limited within narrow confines, yet our advance within them is the 

 more certain. 



1 Schleiden, Grundzuge der wissenschaftlichen Botanik, Vierte Auflage, Leipzig, 

 1861. Vorrede, p. viii. 



