No. 578] DROSOPHILA AMPELOPHILA 



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eggs deposited upon it, and fresh banana supplied. Each 

 two batches of eggs — one deposited by a red female, one 

 by a pink female — were placed together in one bottle so 

 that they might develop side by side and under the same 

 environmental conditions. The result of this experiment 

 is shown in Table XII. 



TABLE XII 



ductivity. Eggs of Al-al, Bl-bl, etc.. Were 

 Developed in the Same Bottle 



Segregation with respect to productivity is here evi- 

 dent. Whether the low fertility 7 seen in so large a pro- 

 portion of these flies was due to an actually low egg- 

 production, or whether it was due to something which 

 prohibited development or to some defect in the germ 

 cell owing to which fertilization could not be effected, is 

 not known. That one of the latter possibilities is likely 

 to be realized here can be inferred from the work of Dr. 

 R. R. Hyde in this laboratory. He counted the eggs of 

 hundreds of individuals, and compared them with the 

 number of flies which emerged from them. According to 



7 The term "fertility" is used here, as defined by Hyde, to indicate the 

 number of eggs that complete development and give rise to mature flies. 

 (See Hyde, Jour. Exp. Zcol., August, 1914, p. 185.) 



