212 JOSE F. NONIDEZ. 



The return of the sperm into the vas deferens seems to be pre- 

 vented by the partial or total closure of the orifice of commu- 

 nication. 



The thick fluid within the ejaculatory sac is not poured into 

 the duct ; in flies killed during copulation or shortly after, no loss 

 of fluid could be observed. On the other hand, the spermatozoa 

 do not penetrate the cavity of the ejaculatory sac, as proved by 

 the study of sections of flies killed during ejaculation. In these 



P 



FIG. 3. Female generative organs, ventral view, d, oviducts; d' ', azygos 

 oviduct ; o, ovaries ; p, parovaria ; s, spermathecae ; u, uterus ; u', vaginal por- 

 tion of the uterus ; v, ventral receptacle, represented as uncoiled in this figure. 



the sac appears filled with a coagulated homogeneous fluid, while 

 in the portion of the vas deferens and ejaculatory duct nearest 

 to the organ several bundles of spermatozoa could be seen. 



The only accessory glands present in the male are the so-called 

 paragonia (Fig. i, pr), also termed seminal vesicles in spite of 

 the fact that spermatozoa are rarely or never found in them. 

 They are two large sacs which open into the vas deferens, their 

 openings being placed a little below those of the vasa efferentia. 



