216 



THE AMERICAN NATURALIST 



[Vol. LVI 



Origin. — One small-bristle, forked male was obtained 

 from a mass culture carrying rough and forked. 



More than a year later, a second mutation to small- 

 bristle occurred in an entirely unrelated stock. In this 

 case the single small-bristle male found among the off- 

 spring of one pair was crossed to a female from a ho- 

 mozygous orange small-bristle stock and produced only 

 small-bristle flies. 



Bent ibn) 



Description. — .The wings of b^nt flies are slightly spread 

 out, and are bent at the base so that they slope down 

 toward the body (Fig. 3). They are often slightly crum- 

 pled. The flies hatch as well as their normal sibs but do 

 not breed as readily. 



Origin. — Many bent males were found in a culture of 

 five orange females from stock mated to a single male of 

 different parentage. At least one of the females carried 

 bent, but the exact origin is uncertain. No bent flies were 

 ever observed in orange stock. 



Forked (/) 



Description. — In forked flies, all the bristles are wavy 

 with the ends sometimes forked. The females are sterile. 

 This character is similar to, but less extreme than, stub- 



