404 



THE AMERICAN NATURALIST [Vol. XLIX 



i? ab 



The gametes produced by the F x female are the following. 



YRN YWAb YWN 



GWAb GRN GRAb 



YRAb 



GWN 



The classes of special interest are non-cross-over (J WAV* 

 males which change as the culture gets old into GWN 

 (which is a single cross-over class), and GRX which is 

 the corresponding female class (but heterozygous). 



