576 GENERATION AND DEVELOPMENT. 



along the vasa deferentia into the vesiculse seminales, whence, 

 if not expelled in emission, it may be discharged, as slowly as 

 it enters them, either with the urine, which may remove mi- 

 nute quantities, mingled with the mucus of the bladder and 

 the secretion of the prostate, or from the urethra in the act of 

 defecation. 



The vcsiculce seminales have the appearance of outgrowths 

 from the vasa deferentia. Each vas deferens, just before it 

 enters the prostate gland, through part of which it passes to 

 terminate in the urethra, gives off a side-branch, which bends 

 back from it at an acute angle; and this branch dilating, 

 variously branching, and pursuing in both itself and its 

 branches a tortuous course, constructs the vesicula serninalis. 

 Each of the vesiculse, therefore, might be unravelled into a 

 single branching tube, sacculated, convoluted, and folded up. 



The mucous membrane lining the vesiculse seminales, like 

 that of the gall-bladder, is- minutely wrinkled and set with 

 folds and ridges arranged so as to give it a finely reticulated 

 appearance. The rest of their walls is formed, chiefly of a 



FIG. 214. 



The base of the male bladder, with the .vesiculae semiuales and prostate gland. 

 1. The urinary bladder. 2. The longitudinal layer of muscular fibres. 3. The pro- 

 state gland. 4 Membranous portion of the urethra. 5. The ureters. 6. Bloodves- 

 sels. 7. Left; 8. Right vas deferens. 9. Left seminal vesicle in its natural posi- 

 tion. 10. Dnctus ejaculatorius of the left side traversing the prostate gl and. 11. 

 Right seminal vesicle injected and unravelled. 12, 13. Blind pouches of vesiculse. 

 14 Right ductus ejaculatorius traversing the prostate. (Haller.) 



layer of organic muscular fibres, from which they derive con- 

 tractile power for the expulsion of their contents. 



To the vesiculse seminales a double function may be as- 

 signed ; for they both secrete some fluid to be added to that of 



