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Heredity and Environment 



FIG. 61. SEX -LINKED INHERITANCE OF WHITE AND RED EYES IN Dro- 

 sophila. Parents, red-eyed female and white-eyed male (females are 

 larger than males; F,, red-eyed males andefemales; F 2 , red-eyed females 

 and equal numbers of red-eyed and white-eyed males. The distribution 

 of sex chromosomes is shown through the middle of the figure, the straight 

 rods being X-chromosomes and the hooked rods Y-chromosomes ; the 

 X-chromosomes that carry the factor for red eye are black, those that 

 carry the factor for white eye are unshaded ; the Y-chromosomes carry no 

 factors for eye color. (From Morgan). 



