Occurrence of different systems of gametic reduplication. 



19 



, a) 1 NYNy 

 8 normal yellow b) 6 NynY 

 ' c) 1 NYnY 



F, zygotes ^ „„„„,, „,,,-,, I a) 3 ^jNy 



I I)) 1 ^yny 



( a) 3 nYnY 



I 1)) 1 nYny 



Thus we may expect three ¥■> forms in the ratio 8:4:4, viz. 2:1:1^). 

 These apparently uniform normal yellows will give various com- 

 binations of Fs forms according to the zygotic constitution of Fo parents. 

 The theoretically possible cases are as follows: 



4 plain yellow 



In short, Fs families produced by F2 normal yellows will he com- 

 posed: either of 2 normal yellows: 1 normal whites: 



1 plain yellows Class A, 



or of 3 normal yellows: 1 normal whites Class B, 

 or of 3 normal yellows: 1 plain yellows . Class C, 



or of normal yellows only Class D, 



according as the genetic constitution of the F2 zygotes concerned to 

 the mating. The F3 normal yellows of Class A will again produce four 

 classes in the subsequent generation, and so on. All four classes above 

 mentioned were actually met with, as already described, in mj' experiments. 



') If the 1:2:2:1 system was actually the case, F, zygotic series will be 

 6 NY : ;! Ny : 3 nY, or also the ratio of 2 : 1 : 1 . 



