82 STRUCTURE AND ECONOMY OF THE HORSE. 



principal bleeding takes place in the operation of castration. The 

 veins are large and numerous, and accompany the arteries in 

 their course, together with the nerves, which, although small, are, 

 as well as the absorbent vessels, very numerous. 



The Vas Deferens, as the duct which conveys the seminal fluid 

 is termed, forms a part of the cord, which can readily be distin- 

 guished from the other parts, being stout and firm to the touch. 

 It springs from the small end of the epididymis, at the anterior 

 part of the testicle, and consequently does not at first join the 

 other parts ; it, however, gradually approaches them, and enters 

 the abdomen with them, when it ascends to the pelvis, and 

 passes by the side of the bladder, about an inch posterior to 

 which it terminates in another duct not yet described. 



The Scrotum, or bag in which the testes are found, is com- 

 posed of several coverings. We have externally the skin, which 

 is soft and thin, and usually dark. It is equally divided by a 

 longitudinal ci-ease called the raphe. On cutting through the 

 skin, we find a layer or coat, supposed to be muscular, called in 

 human anatomy the dartos. It is loosely connected by mem- 

 brane with the skin and other parts ; and a portion of it passing 

 upwards from the raphe, divides the scrotum into two equal 

 parts, and thus separates the testicles from each other. 



The thii'd covering of the scrotum is formed by cellular mem- 

 brane. The testicles themselves have two coats ; one intimately 

 connected with the gland itself, and the other external to this, 

 and common to both the testicle and the cord. The latter is 

 called tunica vaginalis, or vaginal tunic, and is formed of peri- 

 toneum, and accompanies the testicle in its descent. After en- 

 veloping the cord and the testicle, it is reflected, so as to invest 

 them a second time, and is thence called the tunica reflexa. 

 Between these two membranes a fluid is secreted for the lubri- 

 cation of the parts, which spurts out in the operation of castra- 

 tion. 



In performing this operation, we therefore first cut through 

 the skin, next the fibrous coat, then the cellular covering ; these 

 membranes belong-ino; to the scrotum. The knife next divides 

 the tunica vaginalis, on which the fluid before spoken of spurts 

 out, and the testicle sj)rings from the bag through the incision. 

 Thus, by one stroke of the knife, we sever no less than three 

 coverings, besides the skin; but there is no occasion to cut 

 through the reflected coat or tunica albuginea, as the white coat 

 immediately enveloping the testicle is termed. 



The testicles at birth are, like those of man, contained within 

 the scrotum ; but, after five or six months, they are drawn up 

 between the external and internal abdominal rings, where they 

 remain six or seven months, and then again descend to the 

 scrotum. 



