36 LIFE AND DEATH. 



than those of other organs. The inadequacy of these 

 explanations suggested the idea of completing them 

 by the aid of the chemistrj'' which was then springing 

 into being. This chemistry, rudimentary as it was, 

 longed for a share in the government of living bodies 

 and in the explanation of their phenomena. Dis- 

 tillations, fermentations, and effervescences are now 

 seen to play their role, a role which was premature 

 and carried to excess. latro-chemistry from the 

 general point of view is only an aspect of iatro- 

 mechanics ; but it is also an auxiliary. Sylvius le Boe 

 and Willis were its most eminent representatives. 

 This theory remained in the background until 

 chemistry made its great advance — that is to say, in 

 the days of Lavoisier. After that, its importance has 

 gradually increased, particularly in the present day. 

 Nowadays, the general tendency is to regard the 

 organic functional activity, or even morphogeny — />., 

 whatever there is that is most peculiar to and char- 

 acteristic of living beings — as a consequence of the 

 chemical composition of their substance. This is a 

 point of capital importance, and to it we must recur. 



The Physico-chemical Theory of Life. — Contemporary 

 biological schools have made many efforts to secure 

 themselves from any slips on the philosophical side. 

 They have avoided in most cases the psychological 

 problem; they have deliberately refrained from 

 penetrating into the world of the soul. Hence, the 

 pliysico-cheinical theory of life has been built up free 

 from spiritualistic difficulties and objections. But 

 this prudence did not exclude the tendency. And 

 there is no doubt, as Armand Gautier said, that "real 

 science can affirm nothing, but it also can deny 

 nothing outside observable facts ; " and again, that 



