540 



MALE ORGANS OF GENERATION. [CHAP, xxxvn. 



Fig. 258. 



increase in the diameter of the canal when it was distended with 

 secretion, b. fig. 257. It passes behind the bladder and terminates 

 in one of the ejaculatory canals, a very short canal which is formed 

 by the union of the vas deferens with the corresponding vesicula 

 seminalis, which is situated a little external to it, upon the posterior 

 surface of the bladder. 



Vesiculce Seminales. The vesiculse seminales are two sacculated 

 receptacles, about two inches in length and about three-quarters 

 of an inch in breadth, situated upon the posterior aspect of the 

 bladder, lying between it and the rectum. They converge 

 towards the point at which they open, and almost meet. The 

 narrow terminal portion (duct) lies for a short distance, pre- 

 vious to the opening in the urethra, surrounded by the prostate. 

 Each vesicula may be unravelled, so as to form a csecal 

 tube, with several diverticula projecting from it. It is very 

 much convoluted, and the convolutions are connected together 

 with areolar tissue, to which arrangement the sacculated appear- 

 ance is due. 



The structure of the vesiculae seminales 

 is very similar to that of the vasa deferen- 

 tia, but their walls are much thinner. 

 There is an outer coat, composed of areo- 

 lar tissue, in which numerous muscular 

 fibre cells are found. They are lined with 

 a thin layer of tesselated epithelium. 



The vesiculas are usually found to con- 

 tain a viscid, mucus-like substance, which 

 may be regarded as their secretion ; and 

 which, no doubt, is of a nature favorable 

 to maintain the vital activity of the sper- 

 matozoa, and serves also to dilute the 

 semen. These organs were formerly looked 

 upon as the receptacles for the semen ; but 

 a comparison of their arrangement, and an 

 examination of their contents, in the lower 

 vertebrata, by no means confirms this 

 view, as our friend Mr. Pittard has re- 

 marked. In the elephant, the vesiculae 

 seminales open into the vasa deferentia, as 

 in man ; but seminal reservoirs are also found in this animal. In 

 man, however, spermatozoa are very generally found in them; and 

 it is probable that they serve partly as receptacles for the semen, 



Vesicula seminalis, after E. H. 

 Weber, a. Ejacnlatory duct. b. Vas- 

 deferens. c. Vesicula seminalis. d. 

 Terminal diverticula. 





