444 



EDWIN CARLETON MacDOWELL 



The first two generations of this final test gave but few flies. 

 From the flies obtained in the second of these generations (cor- 

 responding to generation 51 of the inbreeding) 22 matings were 

 made; these produced 4364 flies that were graded. From the 



CD 



Z 



q: 

 li. 



L 

 



L. 



o 



Z 

 < 



Ui 



2 



EMPIRICAL MEANS AND 

 REGRESSION STRAIGHT LINES 



I I I I I 



2 3 5 6 



GRADES OF PAREKTS 



7 



Fig. 6 Empirical means and regression straight lines in generation 52, 

 selection suspended. 



flies in the third generation, 152 matings were made; 27,133 

 flies from these matings were graded. Besides the common 

 origin of these flies and their long inbred ancestry, one of the 

 most important features of this final test was the environmental 

 uniformity that was obtained by making large numbers of mat- 



