184 MENDELISM 



crossed with white. Thus, if the hybrid plants are bred 

 together or self -fertilized, the resulting cobs will exhibit 

 a proportion of three smooth grains to one wrinkled 

 grain. In an actual example there were obtained 5,310 

 smooth grains and 1,765 wrinkled, or 75-06 per cent. 

 of the former and 24*94 P er cent, of the latter. 



In a further generation the wrinkled grains breed 

 true. On the average one out of every three smooth 

 grains does the like. The remaining two smooth gfains 

 are of hybrid nature, and on self-fertilization yield 

 again the same proportion of three smooth to one 

 wrinkled. Such hybrid grains and the plants into 

 which they develop are spoken of as heterozygotes. 



Thus, if we write B for smooth and b for wrinkled, 

 the following scheme will express the result of crossing 

 together plants which bear these characters, and after- 

 wards self-fertilizing the offspring obtained ; 



P (dominant character) B x b (recessive character) 



F l Bb 



(heterozygote looking like B) 

 on self-fertilization yields 



| , 



I II ~1 



F a BB Bb bB bb 



(extracted (heterozygotes looking like BB) (extracted 



dominant) on self-fertilization each gives recessive) 



~T~ ~T~ ~l I 



BB BB Bb bB bb bb 



(extracted s ' (extracted 



dominant) and so on recessive) 



i I i 



BB BB bb bb 



and so on, and so on, and so on, and so on, 



breeding breeding breeding breeding 



true. true, true. true. 



