BRISTLE INHERITANCE IN DROSOPHILA 459 



5. The correlation method supports the general conclusions 

 previously drawn; there were genetic differences present among 

 the original flies with extra bristles; these were entirely inde- 

 pendent of the main factor that occasioned the monohybrid 

 ratios in crosses; selection propagated the more homozygous 

 flies, so that a race with uniform germ plasm was soon secured. 

 There is no indication that any genetic change occurred during 

 the course of the experiments. 



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