74 THE VETERINARY SCIENCE 



of the hymen is called the vagina. This passage, in structure, 

 resembles the womb, but is not so strong. There are 

 .numerous glands situated along the inner coat or lining which 

 secrete a fluid to lubricate it. The principal use of this organ 

 is to guide the penis during sexual intercourse, and at the 

 time of foaling serves as a passage for the foal. That part of 

 the passage behind the hymen is known as the vulva. It is 

 about four inches long and about two or three inches high, 

 varying according to the size of the mare. In front, it is 

 separated from the vagina by the hymen membrane. It 

 resembles the vagina in structure, and is also provided with 

 little glands in its inner coat to secrete a fluid to lubricate 

 the passage. At the back part of the vulva, or around the 

 outside, is what is known as the lips of the vulva, one on each 

 side of the opening. The outside of the lips is covered by a 

 very fine skin. Just below the skin, they consist of erectile 

 tissue, which is the same kind of tissue as that of the penis 

 of the horse. This tissue is found more abundantly in the 

 lips of the vulva of the young mare than in those of an old 

 mare. The opening between these lips is situated just below 

 the anus, or the opening where the back bowel ends. At the 

 back part of the vulva, on the under side, is an opening, or 

 hole, about large enough for the passage of a man's finger. 

 Through this hole the tube leading from the bladder enters 

 into the passage and allows the urine, or water, to pass into 

 the vulva, through which it runs out of the body. The 

 clitoris is situated on the under side of this passage, just 

 inside the lips. It can be seen in the mare when she works 

 the vulva after passing water. Just below the clitoris are 

 found two or three small glands which secrete the fluid that 

 passes away when the mare is horsing. 



13. Mammary Glands. — Mammary glands, or what is known 

 as the mare's bag, are two in number, situated between the thighs, 

 young animal. In the young mare they are very small, but after 

 the mare is with foal a few months these glands begin to get 

 large, until at foaling time they attain their largest size. They 

 are covered outside by a thin, smooth skin. The substance 

 of them consists of small glands and tubes — the glands 

 secrete the milk from the blood, while the tubes retain or 

 hold the milk until it is drawn away from the bag either by 

 milking or by the young animal's sucking. During the time 

 of suckling the young, the glands are largely supplied with 



