SCOPE OF GENETICS 13 



So far we have been considering the 

 synthesis of the individual from ingredients 

 brought into him by the two gametes. In 

 the next step of our consideration we reverse 

 the process, and examine how the ingredients 

 of which he was originally compounded are 

 distributed among the gametes that are 

 eventually budded off from him. 



Take first the case of the components in 

 respect of which he is pure-bred. Expec- 

 tation would naturally suggest that all the 

 germ-cells formed from him would be alike 

 in respect of those ingredients, and obser- 

 vation shows, except in the rare cases of 

 originating variations, the causation of which 

 is still obscure, that this expectation is 

 correct. 



Hitherto though without experimental 

 evidence no one could have been certain 

 that the facts were as I have described them, 

 yet there is nothing altogether contrary to 



