GENES AND CHARACTERS 



313 



chromosome but one bearing the gene for red eyes and the other 

 for white. Any egg which receives the x chromosome of the 

 male will produce a female, therefore the F2 generation contains 



r\ r\ 



Fig. 180. — Diagram of the cross between a red-eyed female and white-eyed 

 male of Drosophila melanogastcr. W indicates red and iv white. (From 

 Morgan et al., Mechanism of Mendelian Heredity, with the permission of 

 Henry Holt and Company.) 



