54 



THEORY OF EVOLUTION 



of a different organism. We can explain this 

 result as due to the assortment of factors for 

 these characters in the germ cells according to 

 a definite law. 



As a second illustration let me take the clas- 



F' 



Y R 



•^P YR 



PARENTS 

 YR GW 



G W 



YW 

 YW 



GR 

 GR 



GW:u!ii'' 

 GWiyj" 



Fig. 23. Diagram to show the history of the factor pairs 

 yellow-green and round-wrinliled of the cross in Fig. 21. 



