SEX-LINKED INHERITANCE IN DROSOPHILA " 97 



There were ten cases of crossing-over in 951 males, and eleven 

 cases in 1022 females. In the former there were seven cases in 

 one direction (SWN and LWN) balanced by only three cases in 

 the opposite direction (LRY) ; but the latter are known to be 

 less viable. In the females the eleven cases were in the same 

 direction (SWN and LWN) . Of these nine occurred in one bottle, 

 suggestive of some error. 



In wing characters there were LRN d" 301, while SRN c? = 

 150; LRB c^ = 90, while SRB ^ = 36; on the other hand, SWY 

 cf = 174, while LWY c^ = 116; SWBr cf = 48, while LWR c^ 

 = 36. The sum of the 'straight' males is 613, and the cross-overs 

 332, approximately 2 to 1. 



SHORT, RED, BLACK BY LONG, WHITE, NORMAL 



When females SRB are mated to LWN, the female offspring 

 are LRN, and the males SRN. The second generation is given 

 below: 



SRB 9 by LWN c? 



Fi 



Pi 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 13, NO. 1 



