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- 



o 



Y R 



PARENTS 



YR GW 



'YR 



YW 

 YW 



GR 

 GR 



YR 



YW 



YR \| YR 



YW GR 



W\l YW 



)! 



YWX ' GR 



GR 

 YR 



GR 

 YW 



GW y^wN piN 



YR \YW/ GR 



GW 



CW.- 



YR 

 GW 

 TiT 

 GW, 



FIG. 22. Diagram to show the history of the factor pairs 

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



