THE MECHANISM OF HEREDITY 57 



When these two forms were crossed all of the hybrid's 

 seeds appeared round and yellow (AB) like those of the 

 seed parent; that is, the round character and the yellow 

 character were each dominant. 



When these ~F\ seeds were sown and the plants self- 

 fertilized, four kinds of seeds appeared in the progeny 

 in the four combinations that were possible, with the 

 following numbers of each : 



AB round and yellow 315 



aB wrinkled and vellow 101 



t/ 



Ab round and green 108 



ab wrinkled and green 32 



These figures stand approximately in the relation of 

 9AB to 3aB to 3Ab to lab. The forms appeared to 

 belong to but four homogeneous classes (phenotypes). 

 This was due to the phenomenon of dominance masking 

 the difference between homozygotes and heterozygotes. 

 By their behavior in the next generation they were found 

 to belong to nine really different classes. 



From the round yellow seeds (apparently AB) were obtained by 

 self-fertilization : 



(1) A ABB seeds all round and yellow 38 



(2) AABb seeds all round, yellow and green 65 



(3) AaBB seeds all yellow, round and wrinkled 60 



(4) AaBb seeds round and wrinkled, yellow 



and green 138 



From the round and green seeds (apparently Ab) were obtained: 



(5) AAbb seeds all round and green 35 



(6) Aabb seeds all green, round and wrinkled 67 



From the wrinkled and yellow seeds (apparently aB) were obtained: 



(7) aaBB seeds all wrinkled and yellow 28 



(8) aaBb seeds all wrinkled, yellow and green 67 



From the wrinkled and green seeds (apparently ab) were obtained: 



(9) aabb seeds all wrinkled and gTeen 30 



