972 MALE ORGANS OF GENERATION. 



rather tortuous, but afterwards becoming straight, it ascends upon the inner 

 side of the epididymis, aud along the back of the testicle, separated from 

 both, however, by the blood-vessels passing to and from the gland. Continu- 

 ing, then, to ascend in the spermatic cord, the vas deferens accompanies 

 the spermatic artery, veins and nerves, as far as the internal abdominal 

 ring. Between the testicle and the external ring its course is vertical : it 

 lies behind the spermatic vessels, and is readily distinguished by its hard 

 cord-like feel. Having passed obliquely upwards and outwards along the 

 inguinal canal, and reached the inner border of the internal abdominal ring, 

 it leaves the spermatic vessels (which extend to the lumbar region), and turns 

 suddenly downwards and inwards into the pelvis, crossing over the external 

 iliac vessels, and turning round the outer or iliac side of the epigastric 

 artery. Running beneath the peritoneum, it reaches the side of the bladder, 

 curves backwards and downwards to the under surface of that viscus, and 

 then runs forwards to the base of the prostate gland. In its course within 

 the pelvis, it crosses over the cord of the obliterated hypogastric artery, and 

 to the inner side of the ureter. Beyond this point, where it ceases to be 

 covered by the peritoneum, it is found attached to the coats of the bladder, 

 in contact with the rectum, and gradually approaches its fellow of the oppo- 

 site side. Upon the base of the bladder, the two vasa deferentia are situated 

 between two elongated receptacles, named the seminal vesicles ; and, close 

 to the base of the prostate, each vas deferens ends by joining with the duct 

 from the corresponding seminal vesicle, which is placed on its outer side to 

 form one of the two common seminal or ejaculatory ducts. 



The vas deferens measures nearly two feet in length. In the greater part 

 of its extent it is cylindrical or slightly composed, and has an average diameter 

 of about one line and a quarter ; but towards its termination, beneath the 

 bladder, it becomes enlarged and sacculated, approaching thus in character 

 to the seminal vesicle. Previously to its junction with the duct of that vesicle, 

 it again becomes narrowed to a fine cylindrical canal. The walls of the vas 

 deferens are very dense and strong, measuring one-third of a line in 

 thickness ; whilst, on the other hand, the canal is comparatively fine, its 

 diameter being only from one-fourth to one-half a line. In the sacculated 

 portion the passage is much wider, and the walls are thinner in proportion. 



Besides an external areolar investment, and an internal lining mucous 

 membrane, the vas defereus is provided with an intermediate thick tunic, 

 which is dense in structure, some what elastic, and of a deep yellowish colour. 

 This coat consists principally of longitudinal muscular fibres, mixed with 

 some circular ones. Huschke describes two longitudinal layers with in- 

 termediate circular fibres. The external and middle layers are thick and 

 strong ; but the internal longitudinal stratum is extremely thin, constituting 

 not more than -^th of the muscular coat. The vasa deferentia of the 

 dog, cat, and rabbit were found by E. Weber to exhibit lively peristaltic 

 contractions when stimulated by means of electricity. 



The surface of the mucous membrane is pale ; it is thrown into three 

 or four fine longitudinal ridges, and, besides this, in the sacculated portion of 

 the duct, is marked by numerous finer rugae which enclose irregular poly- 

 hedral spaces, resembling in this the lining membrane of the vesiculaa semi- 

 nales. The epithelium is of the columnar kind, not ciliated. 



Vas aberrans. This name was applied by Haller to a long narrow tube, 

 or diverticulum, discovered by him, and almost invariably met with, which 

 leads off from the lower part of the canal of the epididymis, or from the 

 commencement of the vas deferens, and extends upwards in a tortuous 



