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THE PRINCIPLES OF HEREDITY 





Photo by Winchester 



Fig. 32.3. The fruit fly, Drosophila mclanogastcr, a valuable animal for genetic re- 

 search. The upper picture shows the vials containing larvae, pupae, and adults ; the 

 lower picture shows a male on the left and female on the right, greatly enlarged. 

 These flies are ideal for genetic experiments ; they are easily raised in small vials, 

 require little food, have a life cycle of only about ten days, and exhibit many easily 



recognized hereditary distinctions. 



