THE AMERICAN NATURALIST [VOL.XLVHI 



duce apterous. The others, therefore, are ignored. Con- 

 sidering the second type alone, the analysis becomes : 



F 1 gametes (expected) A P b~A P B-a v b-apB , 

 Apb-ApB-apb-opB. 



F 2 Expected 



classes. 



OpB-OpB 



apterous' fhete'roz ns for bl k) 





ap erous ( e erozygons or .> ac ). 



a v B-A P B 



wmge , gray. ^ 





wmg , e erozygous or ac . 







a'b'a'b 



apterous' Mack ^ 01 * 8 ^ ^ '* 



(hb-ApB 



winged, heterozygous for black. 



a v b-A P b 



winged, black. 



A P B-apB 



winged, gray. 



A P B-a v b 



winged, heterozygous for black. 



ApB-ApB 



winged, gray. 



ApB-Apb 



winged, heterozygous for black. 



Apb-apB 



do. 



Apb-apb 



winged, black. 



Apb-ApB 



winged, heterozygous for black. 



A v b-Apb 



winged, black. 



Expected ratios : 3 winged black ; 6" winged heterozygous 

 for black; 3 winged gray; 1 apterous black; 2 apterous 

 heterozygous for black ; 1 apterous gray. 



Actual results : winged black, winged heterozygous for 

 black, and apterous gray, as shown in Table VI. 



In the last two matings black and heterozygous off- 

 spring were counted as one class. 



Total: winged 701; apterous 174 or 4.02:1. 



The expectation for the F., if A P and B segregate inde- 

 pendently is equal numbers of black and gray among the 

 winged and among the apterous offspring. Actually, how- 

 ever, the apterous flies are all gray, and the winged flies 

 are all black or heterozygous for black. Furthermore, the 



