22O 



JOSE F. NONIDEZ. 



whose function is not well known. They probably prevent the 

 sinking of the egg when laid on the fermented fruit, thus allow- 

 ing the hatching larvae to creep over the food without being 

 asphyxiated. These appendages (Fig. 7, a) arise from one of 

 the surfaces of the egg. For descriptive purposes I will call it 

 the dorsal surface since it is applied against the dorsal wall of 

 the uterus when the egg is within the latter. 



The end of the egg nearest to the place from which the ap- 

 pendages arise bears a conical structure, the micropyle cone (m), 

 which is pierced by an extremely narrow canal, the micropyle. 

 Observed under higher power, the micropyle cone appears hol- 

 low (Fig. 8, c) with the cytoplasm of the egg (/>) penetrating its 



FIG. 8. Ventral and lateral views of the micropyle cone of D. melanogaster 

 drawn from the fresh egg. m, micropyle ; p, protoplasm of the egg penetrating 

 into the micropyle cone. 



interior. The canal or micropyle (m} goes from the tip of the 

 cone towards its base and is placed on the side continuous with 

 the ventral surface of the egg. The pole of the egg bearing the 

 micropyle is always directed toward the anterior end of the ani- 

 mal, either when in the ovary (Fig. 3) or when in the uterus 



(Fig. 9)- 



In the portion of the dorsal surface in front of the appendages 

 there is an area more transparent than the rest of the chorion, 

 which could be termed the operculum in the event of the escape 

 of the hatching larva through this region of the egg. However, 

 this does not always happen, the anterior end of the egg splitting 

 rather irregularly and further ventrally than this. 1 The lateral 

 borders of the transparent area form a ridge which appears as a 

 thin plate at the apex of the egg, passing ventrally the micropyle 

 cone. 



i I am indebted for this observation to Dr. A. H. Sturtevant. 



