36 T. H. MORGAN AND ELETH CATTELL 



LWBYBrX — LWByBrX — SRbYBrX — SRbyBrX \ 

 Gametes SWBYBrX — SWBYBrX — LRbYBr — LBbyBrX / ^^^ 



of Fi 



LWBYBrX — LWByBrX — SWbYBr — SVVbyBr Sperm 



Females Males 



LWN 6 LWN 3 SWN 3 



LRN 6 SRYelS LRY 3 



^' LWBl 2 LWBl 1 SWB 1 



LRBl 2 SRBr 1 LWBr 1 



There were 13 cases of crossing over in the 1178 males or 1 to 

 90. Of these crossings 11 were in one direction, and 1 in the 

 other. 



The reciprocal cross gave the following results: 



SRY 9 by LWB d' 



LRN 9=9 

 SRY & = 181 



F, 



25. 



1 One LWY found in Fi 



There were 20 cases of cross-overs amongst 500 males, or 1 in 



