f THE SKIN. 407 



THE SKIN. 



The skin, or hide, is a thick, chistic structure, which covers 

 the entire frame of the animal. Its uses are numerous and 

 important. It is a protection to the parts beneath it against 

 external violence, and preserves the due form of the body. 

 It is the seat of millions of little glands and tubes, or pores, 

 which are named according to 'the purpose they serve. The 

 glands are the sebaceous or oil glands, and the pores, or tubes, 

 are the sweat or exhalant pores, the absorbent pores, the pores 

 which throw out the oil secreted by the oil-glands. The true 

 skin is also penetrated by the hair-bulbs from beneath, and 

 from which, on arriving at the cuticle, or scarf-skin, the hairs 

 arise. The skin is also penetrated and traversed by numer- 

 ous blood-vessels and nerves. 



The skin, or hide, is composed of three different layers, 

 named from within outward — the cutis, or true skin, the rete 

 mucosum, and the cuticle, or scarf-skin. 



The cutis, or true skin, constitutes the main bulk of the hide 

 of the animal. It is chiefly composed of a fibrous structure, 

 with many little vessels and nerves passing through it. It is 

 very tough and elastic, and highly sensitive, as shown when 

 it is exposed by the removal of the parts covering it, as in 

 chafing by the collar or when a blister has been applied. It 

 is the part of the hide which, when tanned, is leather. It is 

 of different thickness and density, or solidness, on different 

 parts of the animal, and on some parts is drawn very tight 

 while it is quite loose on others. It is capable of adjusting 

 itself to the greatest extremes of the horse's condition, fitting 

 him with equal exactness in the best order and w^hen poorest 

 in flesh. It is of very different degrees of thickness in the 

 different breeds of horses — ^thin and sensitive in the blooded 

 horse, and quite thick in the coarser breeds. 



The numerous little glands spoken of are seated in this 

 part, and from them arise and pass outward the pores before 



