ORGANIC REGULATION 113 



mechanistic explanation implies the assumption of 

 more and more definite and complex physical and 

 chemical structure in the body, and the development 

 and maintenance of this structure has then to be 

 accounted for, with a resulting relapse into vitalism, 

 whether acknowledged or only implied. The help- 

 less struggling in this direction of the mechanistic 

 school which still represents modern orthodox physiol- 

 ogy will be a marvel to future generations. It is in 

 vain that the mechanistic theorists endeavour to exor- 

 cise what du Bois-Reymond called the "spectre of 

 vitalism." This spectre is nothing but the shadow 

 cast by the mechanistic theory itself a shadow which 

 has only become, and could only become, deeper the 

 longer the mechanistic theory has lasted. 



Both the mechanistic and the vitalistic schools have 

 survived up to the present day, but we can under- 

 stand that actual investigators have preferred to avoid 

 vitalism so far as they could, as the vitalistic hypothe- 

 sis seemed to set a limit to experimental investigation, 

 and they rightly and instinctively felt that there is no 

 such limit. So long as vitalism seemed the only alter- 

 native to mechanistic interpretations, they were driven 

 towards the latter. In the din of controversy between 

 vitalists and mechanists there was, however, a com- 

 plete failure to go to the root of the matter, and en- 

 quire into the validity of the assumptions as to physi- 

 cal reality which were accepted by both sides. 



In considering the facts of physiology we have 

 hitherto looked at them from the standpoint of the 

 individual organism only. But we know that in all 



