MENDELISM 



129 



Remembering that A and B are dominant over a and b, 

 the cases under I. will all appear like AB. We get, there- 

 fore, nine AB. Those under II. will all be like Ab ; we 



B 



Fig. 52. — Punnett's Square for Dihybrids, 



A, female gametes arranged vertically ; B, male gametes arranged 

 horizontally ; C, male and female gametes superimposed. 



have, therefore, three Ab. Those under III. will all be 

 like aB ; we have three aB. And the case of IV. will 

 appear like ab — that is, we have one ab. 

 We get, accordingly, in the second hybrid generation Fg 



17 



