CHAPTER XXI. 



THE SKIN AND ITS DISEASES. 



The skin of the liorse consists of three layers. Externally is 

 the cuticle, epidermis, or scarf-skin, composed of innumerable thin 

 transparent scales, like those of a fish. They are raised in the 

 form of pellucid bladders in blistering, and are thrown ofi' in hard, 

 dry, white scales, in mange and some other diseases. The scarf- 

 skin is permeated by innumerable pores, for the passage of the 

 hair, perspiration, and unctuous secretions, and for the inha- 

 lation of gasses and fluids. It is destitute of nerves and blood- 

 vessels, is insensible, and its principal use seems to be to protect 

 the true skin, and to moderate its occasional morbid sensibility. 

 There is a constant alteration and renewal of every part of it, 

 but it adheres to the true skin through the medium of the pores, 

 and also numerous little eminences, or projections, which seem to 

 be prolongations of the nerves of the skin. 



Beneath the cuticle is a thin, soft substance, through which the 

 pores and eminences of the true skin pass. It is termed the 

 rete 7micosu')n, from its web-like structure, and its soft mucous 

 consistence. Its office is to cover the minute vessels and nerves 

 in their way from the cutis to the cuticle. It is also connected 

 with the color of the skin. 



The cutis, or true skin, lies beneath the rete mucosum. It is 

 decidedly of a fibrous texture, elastic, but with difficulty lacerated 

 — exceedingly vascular, and highly sensitive. 



The skin answers the double purpose of protection and strength. 

 Where it is necessary that the parts should be bound and knit 

 together, it adheres so tightly that we can scarcely raise it. Thus 

 the bones of the knees and the pasterns and the tendons of the 

 legs, on which so much stress is frequently thrown, are securely 

 tied down and kept in their places. 



Of its strength we have abundant proof, both in the living and 

 dead animal. 



It is, while the animal is alive, one of the most elastic bodies 

 with which we are acquainted. It not only perfectly adapts it- 

 self to the slow growth or decrease of the body, and appears 



