REPRODUCTION IN DROSOPHILA. 



225 



mated to males of the same generation, then is9lated in vials, the 

 food being changed daily. When the first sterile eggs were laid 

 by each fly it was dissected and the conditions of the spermathecse 

 carefully observed. The following table shows the result of this 

 experiment, in which the number of eggs laid each day was not 

 recorded. 



TABLE I. 



With the exception of fly No. I, which laid some sterile eggs 

 while the spermathecse still retained spermatozoa, all the other 

 flies showed no spermatozoa at all. Whether the sterile eggs 

 laid by such a fly had received spermatozoa or not is a point im- 

 possible to settle. It is possible that the sterility in this case was 

 related to intrinsic factors in the egg, rather than to a failure in 

 the discharge of the spermatozoa from the receptacles. The ven- 

 tral receptacle appeared empty in all of the flies except specimen 

 No. 9 which showed a quite irregular behavior in the rate of lay- 

 ing. I do not know the causes of the retention of spermatozoa 

 in the ventral receptacle of this fly, which appeared entirely 

 normal in other respects. 



These results show that all the spermatozoa, whether they are 

 stored in the ventral receptacle or in the spermathecse, are used in 

 fertilization. The presence of foldings in the epithelium lining 

 the anterior pouch of the uterus probably plays an important role 

 in the fertilization of the eggs by spermatozoa coming from the 

 spermathecse, since such outgrowths of the epithelium form deep 

 grooves along which the spermatozoa may progress until they 

 reach the empty space left between the egg and the walls of the 

 uterus. 



