114 



THE AMEBIC AN NATURALIST [Vol. XLIX 



IXFLFEXCE OF THE FACTOR FOR YELLOW IX THE REALIZA- 

 TIOX OF THE ABNORMAL CONDITION 



Experiments similar to those with black were made 

 with yellow. Yellow, white-eyed normal flies were bred 

 to gray, white-eyed abnormal. In ten tests, the F x fe- 

 males were abnormal in eight cases, and normal in two. 

 It is not apparent that the yellow factor has any decided 

 influence on the results. 



In order to compare the females heterozygous in black 

 and in yellow, and others also homozygous in both, the 

 four following tests were made. By utilizing the red and 

 the white eye colors it was possible to distinguish be- 

 tween the different classes of females. Previous experi- 

 ments, described above, had made it highly probable, that 

 no effects are produced by red and by white, but by making 

 reciprocal crosses here this possible effect was more cer- 

 tainly eliminated. In all cases the females were mated 

 separately for a few days to gray, white-eyed abnormal 

 males to better ensure fertilization and were then brought 

 together in one bottle. 



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