MENDELIAN SEGREGATION 



19 



WHITE 



FIG. 10. White-eyed female by red-eyed male (D. ampelophila). 

 The factors for these characters are carried by the X chromosomes, the 

 factor for red by the black X, and the factor for the white by the plain X. 

 The history of the chromosomes is shown in the middle of the diagram. 



