426 



Aneuploids and Nondisjunction 



White eyed ^ Red eyed cf 



W-- -'W 



X 



+ -• 



K 



Nondisjunction (l): 



Sperm Sperm 



W-- -■ w 



Triplo-X: usually lethal 



White female (XXY) 



Polar body 



Sperm Sperm 



Nondisjunction (2): 



None 



Red male; sterile Lethal 



Fig. 117. Diagram showing the result of nondisjunction of the X chro- 

 mosome of Drosophila melanogaster in the female of a cross between a 

 white-eyed female and a red-eyed male. The normal result of such a cross 

 is red-eyed females and white-eyed males, but as a result of nondisjunc- 

 tion white-eyed females and red-eyed males are produced. 



