BRISTLE INHERITANCE IN DROSOPHILA 



445 



ings at the same time from the same banana culture. All the 

 matings that produced the third generation in this series (gen- 

 eration 52) were made on the same day, in bottles uniformly 

 supplied from the same banana culture. The 152 matings that 

 gave rise to the fourth generation were all made on one of two 

 days one week apart; those mated on the first day were trans- 



Q. 

 U) 

 li. 

 b. 

 O 



if) 

 Z 

 < 



u 



1 



EMPIRICAL MEANS AND 

 REGRESSION STRAIGHT LINES 



GENERATION 53, 



3 4 5 6 7 



GRADES OF PARENTS 



Fig. 7 Empirical means and regression straight lines in generation 53, selec- 

 tion suspended. The broken lines connect means from only one pair of parents. 



ferred to new bottles the day the second lot of matings was 

 started; on each day all bottles w^ere made up from the same 

 food. 



Results 



The empirical means of the offspring arranged according to 

 the grades of the parents are shown in figures 6 and 7. As in 

 former cases, the mean of the two parent grades has been used 



