Variation and Heredity 485 



RECESSES 



Parent (dominant yellow) Y X W (recessive white) 



t 

 I 



Y (W) 



t 

 -. 



Y (W) + (W) Y (W) Y 



or 



F 2 Y _ 2 Y (W) _ W 



t 



2 Y (W) + 2 (W) Y 



or 

 F 3 4 Y 2 Y 4 Y (W) 2 W 4 W 



. 



4Y(W)+4(W) Y 



or 

 F 4 16 Y 8 Y 4 Y 8 Y (W) 4 W 8 W 16 W 



t 



" 



I 8 Y (W) + 8 (W) Y | 



or 

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



12(TY~~ 16 Y^WJ 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. 



