258 



MULTIPLE FACTORS 



effect on subsequent generations. Exactly the 

 opposite results are expected when the population 

 is heteroenegous for multiple factors at the beginning 

 (see Fig. 62). In the latter case, selection of the 

 mixed material will lead to the isolation of definite 



n 



Fig. 62. — L Five pure lines of beans {A, B, C, D, E), and the popula- 

 tion (A-E) that results when they are mixed. IL The upper figure repre- 

 sents the original biotype, and the two figures below this, the two new 

 biotypes that arose from it. (After Johannsen.) 



types and even to the production of new types 

 through recombination. This is the source of most 

 of the success of the practical breeder. 



To what has been said, however, one additional 

 consideration must be urged. Mutations may occur 



