46 CRITICISM OF MECHANISTIC THEORY 



bility, would thus be a solution of the whole 

 problem of life. With every year of physio 

 logical advance, however, we seem to get 

 further and further away from any prospect 

 of such a solution. It was only through the 

 prevailing ignorance of physiological facts 

 that the physiologists of the middle of last 

 century imagined that they were approaching 

 a physico-chemical solution of elementary 

 physiological problems. To us Schwann's 

 theory of cell-growth seems almost as crude 

 as Descartes' extraordinary theory of the 

 mechanism of growth and development. 



In the physiology of the central nervous 

 system the main progress during the last half- 

 century has been in connection with the 

 localisation of function and tracing of paths 

 of physiological connection. Until recently, 

 at least, but little has been done in the 

 direction of a thorough examination of the 

 elementary problems presented by the 

 simplest cases of ' reflex ' action. The work 

 of Sherrington and others is now, however, 

 throwing new light on these problems, and 

 it seems quite clear that the old idea of simple 

 and definite ' reflex mechanisms ' in the 



