EYE COLOE IN DROSOPHILA MELANOGASTER 



349 



respect, that the double recessive eosin Svhiting' is pure white in 

 eye color instead if being a pale yellow. Whiting, though much 

 more extreme in its effects than cream II, was found to be com- 

 pletely recessi\T, the eosin males heterozygous for whiting were 

 indistinguishable from the pure eosin males. 



The results of these last two generations show conclusively that 

 there was no sex-linked white present, and this proves that the 

 colorless flies of the former culture ]M67 were likewise (eosin) 

 whiting, the 132 eosin to 38 colorless flies of M67 being an approxi- 

 mation to the 3 : 1 ratio expected for a Mendelian recessive. 



TABLE 7 

 The Fi offspring of a while ! ! 9 from M67 which teas outcrossed to a bar male 



The Fi results obtained from a bar 9 a?id a bar ij' from the above; the bar character 



has been ignored 



The Fs results obtained from a red female and a ivhitel ! o^ from the above 



None of the females of culture M92 were eosin and accordingly 

 none could show whiting. In order to obtain whiting females 

 with which to make up a pure stock of whiting, several of the 

 wild-type daughters were bred to their whiting brothers. A 

 quarter of these wild-type daughters must have been pure for 

 the whiting gene, a half heterozygous, and the remaining quarter 

 free from it. One such selected female proved to be heterozygous 

 for both eosin and whiting, and the cross of this female to the 

 whiting brothers was thus a backcross test (table 7). 



