DEVELOPMENT OF PLANT PHYSIOLOGY 111 



clarified and strengthened by Ingen-Housz, England took no 

 further part in the building up of plant physiology as the product of 

 chemical, physical, and anatomical study. Another great impulse, 

 however, emanated from England, the introduction of the principle 

 of development into botany. This, excepting that of a few fore- 

 runners, was the work of Robert Brown. 



Although this eminent student dealt with development only as a 

 morphological principle and turned it to account especially in tax- 

 onomy, yet his method of viewing the vegetable organism from the 

 standpoint of development at once quickened the study of anatomy, 

 which up to this time had taken into consideration only the mature 

 plant, and must be credited, of course, to physiology. Robert Brown 

 taught the doctrine of ontogenetic development. This, however, 

 paved the way for phylogenetic development, which similarly 

 emanated from England, and had its chief champion in Darwin. 



The principle of phylogenetic development was of importance 

 first in morphology. By the appropriation of physiological methods 

 and by the application of this principle to purely physiological mat- 

 ters, this historical conception entered with happy results into our 

 sphere. We ask, nowadays, not only how this form, species, genus, 

 etc., has arisen, but we also set before ourselves the question, w r ith 

 reference to the process of differentiation and life processes, how 

 far these are referable to direct influence and how far to peculiarities 

 which have become fixed by inheritance in the course of generations. 



Darwin's great influence on the development of our science is not 

 confined to the historical conceptions of physiological phenomena, 

 and in general to that which is connected with the origin and per- 

 petuation of characters beyond the limits of the individual life, with 

 adaptation and inheritance. His conception of organic life has in 

 manifold other ways furthered the development of our science, 

 especially in that he widened our horizon by a unified conception 

 of the whole organic world. 



That to-day there may no limit be drawn between plant and animal 

 physiology, and that we may, with advantage to the botanists and 

 zoologists, and in general to the study of nature, approach a general 

 physiology, is chiefly referable to Darwin's influence, even though 

 in this particular this great student also had his forerunners. 



Fechner, with true insight, had already pointed out the irritability 

 of plants. But he preached to deaf ears : the contemporary physi- 

 ologists were in the bonds of a purely mechanical conception of plant 

 life. A rich harvest came to Darwin through the Power of Movement 

 in Plants, in which he showed that plants, without having nerves, 

 yet are able to receive stimuli, to transmit them, and to react in 

 places which are removed from the point of stimulus. 



Thus was indicated the way to make use in plant physiology of 



