86 



Heredity and Eugenics 



The wrinkled condition of the seeds of sweet corn results 

 from an inability to mature starch grains. The starchy 

 corns, as the name indicates, possess this feature. One 

 may say, therefore, that the germ cells of starchy and of 



sweet corns are differ- 

 entiated by the pres- 

 ence and the absence, 

 respectively, of the 

 ability to transmit 

 starchiness (Fig. 39). 



In the higher plants 

 as in animals the gam- 

 etes or germ cells are 

 simplex in character. 

 Two germ cells, one 

 male (from the pollen) 

 and one female (in the 

 ovule) , fuse to form the 

 duplex cell or zygote 

 that develops into the 

 plant. The zygote is 

 the new plant genera- 

 tion of which the seed 

 (except the seed coat) 

 is but a resting stage 

 of its development. 

 Starchiness and non- 

 starchiness (sweetness) 

 are seed characters. 

 One can see just what seed characters the plant possesses, 

 therefore, as soon as the seed is fully developed. When two 

 gametes both carrying the factor starchiness (5) produce a 



Fig. 39. — Segregation of starchiness and 

 non-starchiness in maize. Above parents and 

 Fi generation, in center F2 generation, below 

 F3 generation. 



