48 CRITICISM OF MECHANISTIC THEORY 



Probably no competent physiologist will 

 deny this. But, it will be urged, it is only what 

 might be expected that vital mechanism, the 

 product of untold millions of years of natural 

 selection, should be extremely complex ; and 

 the fact that it is so affords no real ground for 

 doubting the mechanistic hypothesis. There 

 are many phenomena in inorganic nature which 

 we do not yet understand, but we do not for 

 that reason regard them as having other than 

 physical and chemical causes. 



We must now push our examination a 

 stage further. Let us assume that all the 

 delicate and persistent reactions met with 

 in the living body are due to intra- 

 cellular mechanism produced by natural 

 selection or in any other way, and see 

 whether this assumption will help us to 

 understand the facts. , First of all, let us be 

 clear about what such an assumption implies. 

 Those who have not studied the physiology 

 of the higher and better-known organisms, 

 such as man or some mammal, have often 

 very little conception of the exquisite delicacy 

 of physiological reactions. This delicacy 

 was hardly even suspected in former times. 



