42 THE VETERINARY SCIENCE. 



VaS Deferens.- -These, are the tubes which carry the semen 

 up the back part of the cord through the ing-uinal rings before 

 mentioned. They then pass backwards and upwards, one on 

 each side, to the upper part of the bladder, where they empty into 

 two small pouches or sacs, called the vesiculas seminales, which 

 store up the semen as it is secreted by the testicles, and when 

 full present the appearance of a pear. 



VesiCUlae Seminales. — These sacs or pouches are situated at 

 the upper side, over the neck of the bladder, one on each side, 

 and have the tube which carries the semen emptying into it at 

 the front end, while at the back end of them is a small opening in 

 each one that leads out into another small tube which passes 

 backward and empties into the urethra, which has been mentioned 

 before as carrying the water out from the bladder. The use of 

 these sacs or pouches is to store up the semen or seed of the 

 horse. While the horse is performing sexual intercourse, these 

 sacs or pouches contract, forcing the semen through these little 

 tubes mentioned out into the urethra, which is a tube leading 

 down to the penis. 



The Penis is the main organ connected in sexual intercourse; 

 its substance is formed of what is known as erectile tissue, which, 

 under certain circumstances, becomes enormously distended with 

 blood. Passing up the under side, there is what has already been 

 mentioned, the urethra, or the tube, which carries the water or urine 

 out of the body; and also in the act of intercourse, it carries the 

 semen, thus it is noticed this tube is used for two purposes, as 

 we have already mentioned. 



The Sheath is a loose process of skin which passes down- 

 wards from the scrotum or bag, generally from about four to six 

 inches, according to the size of the animal, and is attached to 

 each side, leaving a hole or opening in the centre through which 

 the penis comes down. The outside of the sheath is covered by 

 a thin, delicate skin, same as that of the scrotum ; inside it is 

 lined by a membrane having a lot of small glands, which secrete 

 a thick dark fluid to lubricate this passage. Sometimes this fluid 

 collects in here and has the appearance of tar. This is an 

 important point to remember, for when it collects to a larg-e 

 extent the sheath has to be washed out. 



The Semen or seed of the horse, when examined under a 

 microscope, is found to contain small objects called spermatozoa, 



