318 GENERATION. 



or are simple channels in the fibrous structure. They are 

 here lined with pavement-epithelium. In the vasa efferen- 

 tia and the epididymis, we have a fibrous membrane, with 

 longitudinal and circular fibres of involuntary muscular tis- 

 sue, and a lining of ciliated epithelium, described by Becker 

 in the bull and the horse, 1 and noted by Kolliker in the human 

 subject. 2 The movement of the cilia is toward the vas defe- 

 rens. In the lower portion of the epididymis, the cilia are 

 absent. The tubular structures of the testicle, the epididy- 

 mis, and the commencement of the vas def erens are shown 

 in Fig. 30. 



At the lower portion of the epididymis, communicating 

 with the canal, there is usually found a small mass, formed 

 of a convoluted tube of variable length, called the vas aber- 

 rans of Haller. 3 (*'., Fig. 30.) This is sometimes wanting, 

 and its function, which cannot be very important, is unknown. 



Vas Deferens. The excretory duct of the testicle ex- 

 tends from the epididymis to the prostatic portion of the 

 urethra, and is a continuation of the single tube which forms 

 the body and globus minor of the epididymis. It is some- 

 what tortuous near its origin, and becomes larger at the base 

 of the bladder, just before it is joined by the duct of the 

 seminal vesicle. Near its point of junction with this duct, it 

 again becomes narrower. Its entire length is nearly two feet. 

 The course of the vas deferens is in the spermatic cord to 

 the external abdominal ring, through the inguinal canal to 

 the internal ring, where it leaves the blood-vessels, passes be- 

 neath the peritoneum to the side of the bladder, then along 

 the base of the bladder by the inner side of the seminal vesi- 

 cle, finally joining the duct of the seminal vesicle, the com- 



1 BECKER, Ueber Flimmer epithelium und Flimmerbewegung im Greschlechtsap- 

 parate der Saugethiere und des Menschen. Untersuchungen zur Naturlehre des 

 Menschen und der Thiere, Frankfurt a. M., 1857, Bd. ii., S. 77. 



2 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 676. 



8 HALLER, Elementa Physiologies, Bernae, 1765, tomus vii., p. 449. 



