SPONTANEOUS GENERATION 199 



Japp remarks that physiologists are naturally more 

 attracted to Pasteur's subsequent work, in which 

 the biological element predominates ; in fact, he 

 doubts whether many of them have given much 

 attention to the earlier work. And yet it ought 

 to be of interest to physiologists, not merely 

 because it is the root from which the later work 

 springs, but because it furnishes, he is convinced, 

 a reply to the most fundamental question that 

 physiology can propose to itself, namely, whether 

 the phenomena of life are explicable in terms of 

 chemistry and physics ; in other words, whether 

 they are reducible to problems of the kinetics of 

 atoms or whether, on the contrary, there are certain 

 residual phenomena, inexplicable by such means, 

 pointing to the existence of the directive force 

 which enters upon the scene with life itself and 

 which, whilst in no way violating the laws of the 

 kinetics of atoms — though indeed acting through 

 these laws — determines the course of their operation 

 within the living organism. 



This latter aspect of the question is what is 

 generally understood by vitalism, 



Pasteur's view was that compounds which are 

 optically active, that is, have the power of rotating 

 the plane of polarisation of light right-handedly 

 or left-handedly as the case may be, were never 

 obtained except by the intervention of living 

 substance, and, as Japp remarks, hardly any experi- 

 mental method of fundamental importance for the 

 separation and transformation of optically active 



