214 



BREEDING 



It is not permissible for the Mendelian to argue in 

 this way, " I start with my theory to account for the 

 phenomenon of segregation in the 1:2:1 ratio ; from 

 this I derive the 9:3:3:1 ratio ; from this, in its 

 turn, I derive the 9:3:4; and so on. I am like a con- 



AB 



(J gametes 

 Ab aB 



ab 



AB 



(D 



O 



I 

 Ol- 



Ab 



aB 



ab 



jurer who balances successive objects one on the top of 

 the other. Surely if the first object were insecure, 

 the whole series would totter. Surely there could be 

 no better evidence of the truth of the theory which 

 constitutes the foundation than the fact that the 

 successive predictions based on it, and then on one 

 another, are fulfilled." The answer to this is that 

 the fulfilment of the successive predictions would 



