68 CHAPTER 6. 



101. Glands of the skin. 



In the skin, having their origin a little below the true skin, are two 

 sets of glands, namely, the " sweat " and the " oil " glands. 



The Sweat glands secrete perspiration, and terminate by long-necked 

 tubes on the surface of the skin. Though each gland is minute in itself, 

 yet collectively they form one of the largest secreting organs in the body. 

 Erasmus Wilson, in his work on the skin, says that he has counted as 

 many as three thousand in a square inch of skin taken from the palm of 

 a man's hand. The number of sweat glands, however, varies greatly in 

 different parts of the body. 



The Oil glands secrete an oily material. They open, some on the 

 surface, but mostly into the tubes of the hairs. Each hair tube is fur- 

 nished with one or more of these glands. Wherever there is much fric- 

 tion or motion in the skin, the oil glands are very numerous, as, for 

 example, at the heels, and in the bend of the knee and hock. 



102. Perspiration. 



It has been said, and we believe correctly, that a horse in hard condi- 

 tion and hard work gives off through the pores of the skin, or, in other 

 words, by means of the sweat glands, during the twenty-four hours, an 

 amount equal to that excreted as dung. Perspiration in a greater or 

 lesser degree is always going on, even when the animal is in a quiescent 

 condition. When imperceptible it is called " insensible " perspiration, 

 and when secreted in larger quantities as fluid it is known as " sensible " 

 perspiration. 



Excretion of worn-out materials through the skin, of course, goes on in 

 some degree in the horse in a state of nature ; but the full development 

 of these glands is only produced by hard work, high feeding, and 

 grooming. They are then excited to a greater degree of energy than 

 exists or is required in a state of nature. Hence, artificial means, or, in 

 other words, means greater than those supplied by nature, must be put 

 in action by man in order to maintain the health of the skin. 



The healthy or unhealthy condition of the skin is very readily shown 

 by the appearance of the hair, otherwise called the coat. If the skin is 

 unhealthy, the coat is harsh and dry. Again, if the skin is not properly 

 cleaned, dirt remains, not merely in the coat, as many think, but in the 

 system. A very important set of drains, namely, the glands of the skin, 

 are choked, and the whole system, or in other words, the general health, 

 must in consequence suffer. 



The other drains of the body, namely, the lungs, the kidneys, and the 

 bowels, are in action in the horse in a state of nature as much as in the 

 domesticated animal. Hence, they do not, except in disease, require any 

 artificial stimulus. 



103. Structure of the Hair. 



Hair invests every portion of the skin, with a few minor exceptions. 

 It springs from the cellular tissue, on which the true skin rests. Each 



