28o 



Evolution and Adaptation 



B's are bred together they produce only B's. But when the 

 H's are bred together they give rise to H's, A's, and B's, as 

 shown in the accompanying diagram. In each generation, 

 the A's will also breed true, the B's true, but the H's will 

 give rise to the three kinds again, and always in the same 

 proportion. 



Thus it is seen that the hybrid individuals continue to give 

 off the pure original forms, in regard to the special character 

 under consideration. The numerical relation between the 

 numbers is also a striking fact. Its explanation is, however, 

 quite simple, and will be given later. 



In the actual experiment the results appear somewhat more 

 complicated because the hybrid cannot be distinguished from 

 one of the original parents, but the results really conform 

 exactly to the imaginary case given above. The accompany- 

 ing diagram will make clearer the account that follows. 



A 



A(B) 



\ 



\ 



A(B) 



\ 



\ 



A(B) 



A(B) 



The hybrid, A(B), produced by crossing A and B is like A so 

 far as the special character that we will consider is concerned. 

 In reality the character that A stands for is only dominant, 

 that is, it has been inherited discqntinuously, while the other 

 character, represented by B, is latent, or recessive as Mendel 

 calls it. Therefore, in the table, it is included in parentheses. 

 If the hybrids, represented by this form A(B), are bred 



