PRINCIPLES OF GENETICS 



9 



in the hybrid, yellow round, yellow wrinkled, green round, 

 and green wrinkled (Fig. 8). 



If the fertilization of the four kinds of ovules by the 

 four kinds of pollen grains is at random, there will be 



m^ 



/^ 



_y^ 



GW 



Gw 



gW 



^ 



§w 



/ 



to 



GW 



Gw 



W 



V 



^w 





fQv/\ 



Vsvy 



Fig. 8. 

 Diagram illustrating the sixteen F2 recombinations (from yellow- 

 round and green-wrinkled peas) that result when the four kinds of 

 eggs and the four kinds of pollen grains of the F^ hybrid come 

 together. 



sixteen combinations possible. Remembering that yellow 

 dominates green, and that round dominates wrinkled, 

 these sixteen combinations mil fall into four classes, that 

 are in the ratios of 9 : 3 : 3 : 1. 



The results of this experiment show that it can no 

 longer be assumed that the whole parental germ-materials 



