244 THE PHILOSOPHY OF BIOLOGY 



more penetrating. But does any result of investigation 

 or reasoning justify us in assuming, as a matter of pure 

 speculation, that deviations from the specific type of 

 structure are physically determined in all their extent ? 

 Have we not just as much justification for the belief 

 that these deviations are truly spontaneous, and that 

 they arise de novo ? So we approach, from the point of 

 view of experimental biology, Bergson's idea of Creative 

 Evolution. 



