58 CRITICISM OF MECHANISTIC THEORY 



heredity ; for we have to account, not for only 

 one, but for a large number of stupendously 

 complex reproductive mechanisms within the 

 original germ-plasm, and for their endless 

 division and multiplication. The real difficulty 

 for the mechanistic theory is that we are 

 forced, on the one hand, to postulate that the 

 germ-plasm is a mechanism of enormous 

 complexity and definiteness, and, on the other, 

 that this mechanism, in spite of its abso 

 lute definiteness and complexity, can divide 

 and combine with other similar mechanisms, 

 and can do so to an absolutely indefinite 

 extent without alteration of its structure. 

 On the one hand we have to postulate 

 absolute definiteness of structure, and on 

 the other absolute indefiniteness. 



There is no need to push the analysis 

 further. The mechanistic theory of heredity 

 is not merely unproven, it is impossible. It 

 involves such absurdities that no intelligent 

 person who has thoroughly realised its 

 meaning and implications can continue to 

 hold it. 



It may, perhaps, be argued that although 

 a mechanistic theory of reproduction appears 



