408 



THE AMERICAN NATURALIST [Vol. XLIX 



TABLE XV 

 Parents: BRAb <$ by GWN? 

 P»: GRN$ (or slightly Ab) — GWN £ 



LI 



In the next case eight consecutive F 2 counts are given. The 

 GRAb changes to GRN. In the first three counts there 

 are 221 GRAb to 76 GRN, or 3 to 1. In the last three 

 counts there are 148 GRAb to 296 GRN or 1 to 2. 



TABLE XVI 

 Parents: GRAb £ by YWN $ 

 F,: GRAb 2— YWN J 



Finally six cultures are given in the following table of F a 

 flies from YHX ? by GWAb £ grandparents. The GWAb 

 males change to GWN males and the GRAb females to 

 GRN females. In both cases the increase in the normal 

 flies in the last two or three counts is marked. 



