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. Inan actual example there were obtained 5,310 
smooth grains and 1,765 wrinkled, or 75°06 per cert. 
of the former and 24°94 per cent. of the latter. 
In a further generation the wrinkled grains breed 
true. On the average one out of every three smooth 
grains does thelike. Theremaining twosmooth grains 
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 0 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 4 (recessive character) 
Fy 
Bob 
(heterozygote looking like 2) 
on self-fertilization yields 
F, BB Bb 6B bb 
(extracted (heterozygotes looking like BB) (extracted 
dominant) on self-fertilization each gives recessive) 
| | | | 
Bs BB BB Bb 6B bb bb 
(extracted —S (extracted 
dominant) and so on recessive) 
Fy BB BB bb bb 
and so on, and so on, and soon, andsoon, 
breeding breeding breeding breeding 
true. true. true. true. 
