TEE MALE GENITAL ORGANS. 861 



seminalis. The fibrous coat of the vesiculsB is merely condensed cellular 

 tissue.) The • mucous and muscular coats are supplied with blood by the 

 vesico-prostatic artery (inferior vesical) ; their nerves are derived from the 

 pelvic plexus. 



The richness in glands of the mucous membrane of the vesiculee 

 seminales, has led several anatomists to consider them as organs of secretion, 

 and not as reservoirs for the semen. But the large cavity that each forms, 

 appears to demonstrate that they serve as reservoirs and secretory organs at 

 the same time. Their fluid production is added to the semen, as is the 

 secretion of the prostate and Cowper's glands. 



The ejaculatory duct is very short, and succeeds the narrow canal of the 

 vesicula after the latter opens into the vas deferens. The two ducts pass 

 between the prostate gland and urethra, and, after a brief course, terminate 

 in the latter, on the side of the veru montanum—& tubercle which will be 

 noticed presently. 



Near to, and in front of this tubercle, is a third very small orifice — the 

 opening of the third pouch included between the serous duplicatures joining 

 the vasa deferentia. (This is the sinus pocularis, or utriculus prostatia, 

 vesicula seminalis tertia or media of Gurlt.) Improperly designated the 

 third vesicula, or masculine uterus (Weber), this pouch (sometimes double) 

 secretes a fluid which is thrown into the urethra. (This third vesicula is 

 present in all the domesticated animals.) 



The ejaculatory ducts may become obliterated ; then the secretion of the 

 vesiculfe seminales accumulates in their interior, and gradually distends 

 them until they attain enormous dimensions. We found, in a Gelding, a 

 vesicula which was nearly as large as the bladder ; it contained a brownish, 

 sticky fluid, holding in suspension epithelial cells, free nuclei, and mucus 

 corpuscles. 



(The vesiculse seminales, in addition to their own secretion, receive the 

 semen conveyed by the spermatic ducts, and keep it in reserve until 

 copulation ; when the contraction of its muscular apparatus expels it into the 

 ejaculatory ducts, and from these into the urethral canal.) 



3. The Urethra. 



The urethra is a canal with membranous and erectile walls, commencing 

 at the neck of the bladder, and terminating at the free extremity of the penis. 



Course. — When followed from its origin to its termination, it is seen to 

 proceed at first horizontally backwards, then bend downwards at the ischial 

 arch to leave the cavity of the pelvis, placing itself between the two roots of 

 the corpus cavernosum, and passing forward in the channel formed at the 

 lower border of these, until it arrives at the head (glans) of the penis, where 

 it terminates by forming a small (cylindrical) prolongation, named the 

 urethral tube. In its track, the urethra is divided into two very distinct 

 portions: the intrapelvic, the shortest, and the extrapelvic, the most ex- 

 tensive, and supported by the corpora cavernosa. The latter division being 

 alone enveloped by the erectile tissue that enters into the formation of the 

 urethral walls, has been also named the spongy portion, the first being 

 designated the membranous portion. 



Interior. — Internally, this canal has not the same width throughout. 

 Very constricted at its origin, towards the neck of the bladder, it expands 

 somewhat suddenly at the prostate gland ; its dilatation, improperly named 

 in Man the cul-de-sac of the bulb (bulbous portion), or, better, the ventriculus. 



