THE ORGAN OF TOUCH 



499 



number of holes, some of ■which allow the hairs to pass through, others are 

 the pores through which the sweat is poured out, and others again are 

 follicles for the secretion of sebaceous or half-oily fluid, for the purpose of 

 lubricating the skin. These last are particularly numerous at the flexures 

 of the joints, as at the inner part of the hock, knee, and heel, in each of 

 which situations they are liable to become clogged, leading to the conditions 

 known as mallenders, sallenders, and cracked heels, which will be hereafter 

 described. 



The epideemis, cuticle, or scarf skin, is very thin but tough, and in the 

 horse its innermost layer is generally of a dark slate colour, the better to 

 protect the dermis from the ra3's of the sun. It is composed of scales 

 agglutinated together, and its internal surface is reflected in the form of 



Fio. 84. — Nerves of Sensation 81i??lied to the Lips of the Horse, showing also the Origin of 



THE JuouLAE Vein. 



fine sheaths around all the hairs which pierce it, and of linings to the 

 sweat pores and sebaceous follicles. As fresh cuticle is secreted the outer 

 layers fall off; and in the horse this growth is very rapid, so that in a very 

 few days the coat of hair becomes loaded with them if it is not regularly 

 cleansed. The}^ affbrd a great protection against wind and rain, and for 

 that reason they should not be removed by friction from those horses 

 svhich are abou.t to be turned out of doors. 



The hairy appendages of the skin of the horse are of two kinds : — 1st. 

 The general coat. 2nd. The horsehair, which is of a thicker and stiffer 

 kind, and grows from the top of the neck, forming the mane, from the 

 dock as the tail, from the backs of the legs, and from the eyelids and lips 

 to act as feelers in enabling them to avoid injury. Each hair is secreted by 

 its bulb, which is seated partly in the dermis and partly in the cellular 

 membrane, closely subjacent to the true skin. Unless, therefore, the whole 

 thickness of the dermis is destroyed, the bulb may be safe, and the hair 

 is restored in the course of time. The coat is shed twice a year, in spring 

 and autumn, the secretion from the bulb ceasing for a short period, and the 



