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THE AMERICAN NATURALIST [Vol. XLVIII 



Analysis of the cross: 



A Pf factor necessary for wing production. a v , its alle- 

 lomorph, in the apterous fly. 

 M, factor necessary for the production of long wings 

 (sex-linked). 



m, allelomorph of M responsible for miniature wings. 

 W, factor necessary for the production of eye color 



(sex-linked). 

 w, allelomorph of W responsible for white eyes. 



P x Long, red male A P MWX-A Pf 



Apterous, white female cbmwX-OpmwX. 



F x Long red females ApMWX-chmwX, 



Miniature white males Ap-a P mwX. 



F 2 , leaving out of account the sex-linked factors and 

 considering only winged vs. apterous : 

 Gametes of Fj A P , a,. 



A P , ch. 



Experiment //.—Long vermilion $ by apterous, white J 1 - 4 

 This cross is practically the reciprocal of Exp. I, except 

 that vermilion replaces red eye color in the winged parent. 

 Like Experiment I it involves two pairs of sex-linked char- 

 acters, aside from the apterous character. The results are 

 essentially like those of Experiment I and may be passed 

 over briefly. 



Winged J Av-A v . 



I A P -a P . 



Apterous a P -a v . 



P t Long, vermilion $ A P MWX-A P MWX, 

 Apterous, white <$ (fomwX-a?} 



