HEREDITY AND VARIATION 



215 



Purple(PPj Light Purple (PW) Light Purple(PW) 



if A^i Liaht if A^i 



Purpl? 



Purple 



Purple 



Fig. 123. — Mendel's Law of Inheritance. Longitudinal sections of flowers, 

 showing color of corolla and genetic constitution of the male and female gametes, 

 here represented by ovules in the ovary and pollen grains in the anther. The 

 parents (Pi generation) are in one case purple-flowered {FP) with the corolla 

 represented solid black, and in the other, white-flowered {WW), with the corolla 

 merely outlined. The gametes in the former all carry the factor for purple and 

 are solid black; in the latter, all carry the factor for white. In the first hybrid 

 generation or Fi (PW), dominance of purple is not complete, for the corolla is 

 colored but not as darkly as in the purple parent. Its color is represented by 

 cross-hatching. Note that in the gametes, both male and female, about half 



