PRINCIPLES OF HEREDITY 



661 



flies with one X and three sets of autosomes. These flies, with a ratio of 

 0.33, had all their male characteristics exaggerated; Bridges called them 

 "supermales." Other abnormal individuals, with three X and two sets 

 of autosomes were "superfemales," with all the female characteristics 

 exaggerated. Individuals with two X chromosomes and three sets of 

 autosomes, a ratio of 0.67, were intersexes, with characters intermediate 

 between those of normal males and normal females. All of these unusual 

 flies, supermales, superfemales and intersexes, were sterile. 



All of the eggs produced by XX females have one X chromosome. 

 Half of the sperm produced by XY males contain an X chromosome 

 and half contain a Y chromosome. The fertilization of an X-bearing 



Diploid cells 

 of parents 



Synapsis 



Anaphase of 

 meiotic 

 division 



Egg: 



one type 



Sperm.: 

 two types 



OFFspririg 



equal 



numbers 



of males 



and 



females 



Figure 32.4. Diagram illustrating the transmission of the sex chromosomes of the 

 fruit fly. 



