Variation and Heredity 



485 



GENERA- 

 TION 



DOMINANTS 



HYBRID 

 DOMINANTS 



RECESSIVES 



1 



-V (W). 



t 



F, Y 



or 

 .2 Y (W). 



t 



_w 



2 Y (W) + 2 (W) Y 



F 3 4 Y 2 Y 



or 



A Y (W). 



.2 W 4 W 



4 Y (W) + 4 (W) Y 



F 4 16 Y 8Y 4Y 



or 

 _8 Y (W). 



t 



A W 8 W 16 W 



8 Y (W) + 8 (W) Y 



or 



F 5 64 Y 32 Y 16 Y 8 Y 16 Y (W) 8 W 16 W 32 W 64 W 



120 Y 



16 Y (W) 



120 W 



Upon the principle of the purity of the gametes and the 

 combination of these according to the law of chance, it 

 becomes a simple mathematical problem to determine the 

 number of combinations resulting from a cross in which 

 two or more character pairs are considered. 



