284 THE FITNESS OF THE ENVIRONMENT 



portion of French biologists, as well as those 

 of other nations like Huxley and Du Bois- 

 Reymond, derive their philosophical views 

 concerning their science. Descartes per- 

 ceived, apparently the first among the mod- 

 erns, that the scientific explanation of vital 

 phenomena must be a physical one, in terms 

 of matter and motion. Far in advance of 

 his time he applied such ideas to the nervous 

 system, thereby establishing the nature of 

 reflex action and invading the very citadel 

 of animism. Outside natural science, how- 

 ever, Descartes was far from being a mechan- 

 ist. Since the early seventeenth century the 

 conflict between vitalism and mechanism 

 has ranged over the whole field of biology, and 

 its history is most complicated. After Des- 

 cartes, Lavoisier, by his studies of combustion 

 within and without the body, made the next 

 very important step. He was then followed 

 by Liebig, Wohler, and a host of later chem- 

 ists. 



In the main the growth of exact science has 

 steadily delivered over one vitalistic strong- 

 hold after another to the mechanists. And 

 though in the first flush of triumph mechan- 

 ism has sometimes seemed to gain more in a 

 particular engagement than later proved to 

 be the case, vitalism has perhaps not had a 



