No. 583] ROLE OF ENVIRONMENT IN DROSOPHILA 



3D7 



TABLE IV 

 Parents: BRAb £ by GWN ? 

 F,: GRN or slightly Ab $ — GWN <$ 



vailing at the time, or else the black factor may have had 

 some influence that is favorable to the normal condition 

 in the heterozygous abnormal flies. If the latter were 

 the true explanation we can understand the large num- 

 ber (here) of the GRN class (for two thirds are hetero- 

 zygous in black and intermediate in color) and the com- 

 plete absence of the BWAb class which should be one third 

 as frequent as the GWAb class. A special examination 

 was made to test this possibility and will be described 



TABLE V 

 Parents: BRAb £ by GWN $ 

 Fj: GRN or slightly Ab$— GWN<? 



8 j 11 10 11 



MS j 118 242 | 256 | 100 j 123 



_ 841 1,102 | 1.S00 2,0f,8 j 1,105 1.153 



