VISCERAL ANATOMY. 147 



part of the scrotum becomes obliterated and cut off from the peri- 

 toneal cavity. 



The semen, the combined secretion of the testicles and glands 

 of the urethral canal, is a white, viscid, alkaline fluid, holding in 

 solution the essential elements formed by the testicles the sper- 

 matozoa which are elongated bodies g-^ 7 to -g^ inch long, with 

 an oval head and a filamentous tail. 



VAS DEFERENS. 



This is an elongated canal, as large as a goose quill, beginning 

 at the epididymis and ending at the seminal reservoirs. It passes 

 upward through the inguinal canal, backward into the pel- 

 vis, crossing the ureters, and ends by uniting with the vesicles to 

 form the ejaculatory ducts. 



Structure. 



External, fibrous layer. 



Middle, muscular, of two longitudinal and one circular, layer. 



Internal, mucous, covered with columnar epithelium. 



THE VESICUL.E SEMINALES. 



These are two elongated pouches, which store up the semen 

 for the copulative act; they lie above the bladder, receiving a 

 peritoneal fold. They have a body and an anterior and posterior 

 extremity. Their posterior extremity is tapering and unites with 

 the vas to form the ejaculatory duct. 



Structure. 



1. Serous coat, incomplete. 



2. Fibrous. 



3. Muscular, like bladder, with also some compressor fibres to 

 evacuate the pouch. 



4. Mucous membrane, continuous with ejaculatory ducts, 

 thrown into folds with numerous glands, which furnish a part of 

 the seminal fluid. 



THE EJACULATORY DUCTS 



Are two very short canals succeeding the vesicles, and formed 

 by their junction with the vasa deferentia. They pass above the 

 prostate, finally emptying into the urethra on either side of an 

 elevation, the veru montanum. In front of this is the opening 

 which runs backward into the sac lying between the vesicles and 

 inside the peritoneal pouch. The opening is the sinus pocularis, 



