No. 583] BOLE OF ENVIRONMENT IN DROSOPI1ILA 425 



ular manner though no serious attempt was made to dis- 

 cover the eause of the irregularity. A stock of cream eye 

 color was made up from this strain and selection against 

 the abnormal was carried out in a rough way for several 

 generations, but this selection failed to eliminate the ab- 

 normal condition, and a recent examination of the stock 

 showed that for a year the abnormal abdomen had main- 

 tained itself and was still present in about half of the 

 flies. 



A male was again crossed to a wild type female and 

 gave normal F, flies. In F 2 there were 128 red normal 

 females, 29 red normal males, and 28 eosin normal males, 

 abnormals appeared. Crossed to eosin the Fj were 



