474 THE SKIN AND ITS DISEASES. 



little eminences, or projections, which seem to be prolongations of the nerves of 

 the skin. The cuticle is in itself insensible ; but one of its most important func- 

 tions is to protect and defend the parts beneath, which are so often exposed to 

 the effects of a morbid sensibility. 



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

 eminences of the true skin pass. It is termed the rete mucosum, 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 con- 

 nected with the colour of the skin. In horses with white hair the rete muco- 

 sum is white ; it is brown in those of a brown colour black in the black, and 

 in patches of different colours with those the hue of whose integument varies. 

 Like the cuticle it is reproduced after abrasion, or other injury. 



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. It is the substance which is converted into leather when 

 removed from the body, and binds together the different parts of the frame. In 

 some places it does this literally and clings so closely to the substance beneath 

 that it scarcely admits of any motion : this is the case about the forehead and 

 the back, while upon the face, the sides and flanks, it hangs in loosened folds. 

 In the parts connected with progression it is folded into various duplicatures, that 

 the action of the animal may admit of the least possible obstruction. The cutis 

 is thinnest, and most elastic, on those parts that are least covered with hair, 

 or where the hair is altogether deficient, as the lips, the muzzle, and the inside 

 of the flanks. 



Whatever is the colour of the rete mucosum, the true skin is of a pale 

 white, in fact, the cutis has no connection with the colour of the hair. Of its 

 general character, Mr. Percivall gives a very accurate description : " It ap- 

 pears to consist of a dense substratum of cellular tissue, with which are inter- 

 woven fibres of a ligamentous nature, in such a manner that innumerable areolse, 

 like the meshes of a net, are formed in it. These areolae open, through corre- 

 spondent pores in the cuticle, upon the external surface, and are for the purpose 

 of transmitting thither blood-vessels and absorbents, giving passage to the hair, 

 and lodging the various secretory organs of the skin."* 



Over a great part of the frame lies a singular muscle peculiar to quadrupeds, 

 and more extensive and powerful in the thin-skinned and thin-haired animals, 

 than in those with thicker hides. It reaches from the poll over the whole of 

 the carcase, and down to the arm before, and the stifle behind. By its contrac- 

 tion the skin is puckered in every direction ; and if it acts strongly and rapidly, 

 the horse is not only enabled to shake of any insect or fly that may annoy him, 

 but sometimes to displace a great part of his harness, and to render it difficult 

 for the most expert rider to keep his seat. This muscle also assists the skin in 

 bracing that part of the frame which it covers, and, perhaps, gives additional 

 strength to the muscles beneath. It is called the panniculus carnosus, or fleshy 

 panicle or covering. 



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. It ia in order to take addi- 

 tional advantage of this binding find strengthening power that we fire the legs of 

 overworked horses, in whom the sinews have begun to start, and the ligaments 

 of the joints to swell, or be displaced. The skin is tight along the muscles of 



* Pemvsiirfi Anatomy of the Horbc, p. 400. 



