60 CRITICISM OF MECHANISTIC THEORY 



detail of biological fact and investigation. 

 Biology deals at every point with phenomena 

 which, when we examine them, can be re 

 solved into metabolic phenomena exchange 

 of material and energy, as exemplified in 

 growth, development, maintenance, secretion 

 and absorption, respiration, gross movements 

 in response to stimuli, and other excitatory 

 processes. Now metabolism is itself a con 

 stant process of breaking down and reproduc 

 tion of what is living. There is no reason 

 for separating the reproduction of a whole 

 organism from the constant reproduction of 

 parts of it in ordinary metabolic process. 

 Hence our conception of heredity involves 

 every part of biology ; and if we cannot frame 

 a mechanistic theory of heredity we are 

 equally at a loss in connection with the 

 ordinary phenomena of metabolism, and we 

 have no right to use mechanistic hypotheses 

 in connection with these phenomena. We 

 have also seen already that the ascertained 

 facts do not in any case point to mechanistic 

 theories of the ordinary activities with which 

 biology deals. 



As a physiologist I can see no use for 



