THE LINKAGE OF TWO FACTORS IN DROSOPHILA. 



wYBX Wyb Winged gray cf. 



w YBX w Yb Wingless gray tf . 



WyBX Wyb Winged black rf 1 . 



WyBX wYb Winged gray cf . 



In the FI female, gametes having the composition WYBX and 

 wyBX would be expected on any assumption except that of 

 strong linkage of wY and Wy, and likewise in the male, the 

 gametes WYBX, wyBX, WYb and wyb would be expected. 

 For the sake of convenience I have omitted to represent the 

 cross-over gametes in the above analysis. 



In another cross, miniature-winged, black, white-eyed flies 

 were mated to wingless, gray, red-eyed flies. The result is com- 

 plex, but only in the sense of giving in one cross 20, %, classes, 

 and in the reciprocal cross 13, F 2 , classes. The results, however, 

 as far as linkage is concerned, are perfectly evident. The fact is 

 also brought out that the factor for Wings shows no linkage to 

 the sex-linked factor (C) for eye color, and to (R) the factor 

 in the absence of which the wings are miniature. 



Miniature White Bl cf by Wingless Red Gray $ 



\/ 

 GR Long cf and 9 



Fz Females 



GRL BIRL GR Wingless 



532 268 235 



Males 



GRL GWhL BIRL BIWhL GRM GWhM BIRM BIWhM GRW-g-s GWhW-g-s 

 173 49 81 38 92 165 30 52 117 90 



There are three classes of females and ten classes of males. 

 The wingless flies only occur as Gray no black wingless flies 

 being present. The alteration in the ratios, due to the linkage 

 between the two sex-linked factors C and R, is neglected here. 

 The analysis follows: 



wRMCBYXwRMCBYX Wingless red gray 9 . 

 WrMcByX Wrmcby Min. white black cf. 



wRMCB YXWrMcByX Winged gray red 9. 



wRMCBYX Wrmcby Winged gray red cf. 



