MECHANISTS AND VITALISTS 61 



the hypothesis that life, as a whole, is a 

 mechanical process. This theory does not 

 help me in my work ; and indeed I think it 

 now hinders very seriously the progress of 

 physiology. I should as soon go back to f 1 

 the mythology of our Saxon forefathers as \ V 

 to the mechanistic physiology. 



Although the mechanistic theory of life 

 will soon become a matter of past history, 

 there can be no doubt that it has filled an 

 extremely valuable part in the development 

 of physiology. Again and again mechanical 

 theories of one sort or another have served 

 as temporary working hypotheses round 

 which experimental investigation has centred 

 in physiology. This has been as true of 

 the grosser mechanical hypotheses of the 

 seventeenth century as of the more refined 

 physical and chemical hypotheses of later 

 times. The merit of these hypotheses has been 

 that they were capable of either verification or 

 disproof, whereas the vitalistic theories have 

 been incapable of being experimentally tested. 



Let us try to see why the latter has been the 

 case. The vital force was conceived as some 

 thing acting ' from the blue ' on ordinary 



