FROM THE SOCIETY S GAKDENS. 



685 



lie, one on each side of the middle-sac, and enter by a narrow 

 neck into the narrow section between the end-sac and middle- 

 sac. • The text-fignre shows the connections at this point 

 with the vas deferens. The ditctus ejaculatorius for a consider- 

 able portion of its coui-se on leaving the middle-sac is large and 

 glandular and almost as broad as the middle-sac itself. The 

 narrow canal between the latter and the ductus projects into the 

 lumen of the ductus as a minute cone-shaped, protuberance. 

 The broad upper part of the ductus, after two bends, giving the 

 tube an S-shaped form, nari^ows into a small canal of several 

 coils, which enters lower down into the upper part of the 

 retracted preputial sac. 



Text-figure 29. 



Lipeurus forficulatus, $ . Transverse section through the abdomen at the 

 level of the middle-sac of the vesicula. (Diagrammatic.) 



Rt. rectum. T. testis. 31. muscles. FC. fat cells. VD. vas deferens. 

 R. reservoir. IIS. middle-sac. 



Sections of these parts reveal some important points (see text- 

 figs. 29 & 30). Externally the end-sac is marked by a median 

 longitudinal groove. In cross-section the mid-sac, as in the 

 vesicida seminalls of other insects, is seen to be double, consisting 

 of two distinct tubes closely applied one to the other. Similarly, 

 the middle-sac is also double. Whereas the end-sac contains 

 sperm, the two "reservoirs," the middle-sac, and the two minute 

 vesicles, one on each side at the lower end of the latter, contain a 

 coagulable white secretion, which possibly plays the part of sper- 

 matophragmen, serving for the maintenance of the spermatozoa 

 during copulation. 



The walls of the end-sac are fairly thin. Those of the middle- 



