104 



THE HORSE IN HEALTH AND DISEASE 



scrotum. It is a serous membrane, and directly continues the 

 peritoneum, of wliich it is a pouch-lilve diverticulum. Between 

 the two vaginal tunics is normally found a potential cavity con- 

 taining a serous fluid to prevent friction as the testicle changes 

 position. 



The vas deferens is a thick-walled duct, about | inch in 

 diameter, which carries away the secretion of the testicle. There 

 is one for each of these glands. It passes upward through the 

 inguinal canal to the abdominal and pelvic cavities. It ends by 

 entering the urethra. 



Fig. 33. — Section of prepuce and part of penis: P, Internal part of prepuce 

 or prepuce proper; P', external part of prepuce or sheath; C.p., preputial cav- 

 ity; F.g., fossa of glands; D, diverticulum; P.u., end of urethra. (Sisson, 

 Anatomy of Domestic Animals.) 



The spermatic cord is that mass of tissue which is severed when 

 the stallion is castrated. It is composed of the vas deferens, the 

 blood-vessels, the nerves and the cremaster muscle, and serous 

 coverings of the testicle. 



The seminal vesicles are two sacs, about 6 inches long, which 

 project forward from the dorsal surface of the posterior part of the 

 bladder. In some animals they serve as reservoirs for the semen, 

 but in the horse do not appear to so function. 



The prostate and Cowper's glands lie at the beginning of the 

 urethra. They secrete fluids which are poured into the latter tube 

 for the purpose of facihtating the passage of semen. They also 



