150 



OTTO L. MOHIl 



fly was derived from the stock mentioned and liad the constitution 



— ^, and that consequentlv no contariiinatioii liad occurred. The 



bl pr cii ' 



mosaic was therefore, after liaving been drawn, crossed to homozy- 

 gous bl pr cii females. On the following day three homozygous eosin 

 vermilion forked females from a pure stock were in addition intro- 

 duced in the same culture l)Ottle. (eosin, w^, eye color; vermilion, v, 



TABLE 1. Oiiicrosscs of bl pr cii daughters of the mosaie 



(P.;?4^^"ç?x^ 



bl pr cu 



hi pr cu 



"'cf, exception. I\ ,7,-^,? X wild- type ^^). 



bl pr cu 



eye color; forked, /, bristles; these genes are récessives in the X- 

 chromosome). 



The next day the mosaic was found dead owing to an accident, 

 sticking to the inside of the cultine bottle. But soon numerous larvae 

 .appeared, showing that the male before dying had fertilized some of 

 the females. The culture gave the following offspring (C. 2702, June 

 22, 1922): 25 bl pr cuÇ$; 26 Sk cu $$; 26 bl pr cu cTJ^; 21 Sk cu <S<^. 

 None of them showed any bristle alteration. 



This result proved that the mosaic with regard to autosomal mu- 

 tant genes was of the constitution expected, and that no contamina- 

 tion had occurred. Moreover, since all the offsi)ring were curved and 

 none of the males uy" v f, it was clear that the w^ v f females which 

 were introduced on the second day had not been fertilized. 



