136 THE HOG. 



CHAPTER IX. 



The Skin and itt Diseases Gangrenous Erysipelas Lice Leprosy Mange lie aslcsDcs 

 quamation of the Skin. 



THE SKIN. 



THE skin of the hog, like that of most other animals, is composed 

 of three separate parts or layers. The first or exterior of these is 

 the cuticle or scarf skin, which covers the whole surface of the body 

 and protects the more sensitive parts from the injuries which might 

 result to them from immediate contact with external agents. It is 

 a thin, tough, callous texture, perforated with innumerable holes or 

 pores, through which pass the hairs and bristles, and whence exude 

 those transpirations by means of which the body throws off all 

 vapors injurious to the system. Chemical analysis has proved it 

 to be chiefly composed of gelatine, and consequently insoluble in 

 water of common temperature. This layer is considerably tougher 

 and denser in the hog and other of the pachydermata than it is in 

 the horse, ox, and most of our domesticated animals. 



Beneath this is the rete mucosum, a soft expansion of tissue which 

 overspreads, and can with difficulty be separated from the layer below 

 it. Its purpose appears to be to protect the terminations of the 

 blood-vessels and nerves of the skin, which it in a manner envelops 

 or covers. This layer determines the color of the body and of the 

 hair. 



The third and undermost part is the cutis vera or true skin, an 

 elastic texture composed of innumerable minute fibres crossing each 

 other in all directions, fitting closely to every part of the frame, 

 yielding by its elasticity to all the motions of the body, and interpos- 

 ing its dense, firm structure between the more vital parts of the 

 system and external injuries. Innumerable blood-vessels and nerves 

 pass through it, and appear upon its surface in the form of papillae ; 

 it is in fact far more sensitive than the muscles or flesh. 



The skin varies in density in different breeds of swine. In scmo 

 of the large, old breeds it is thick, coarse, tough, and almost as im- 

 penetrable, in comparison, as the hide of a rhinoceros; while in 

 many of our smaller breeds, and particularly in those which have a 

 considerable admixture of Asiatic blood, and in the Chinese pigs 

 themselves, it is soft, fine, and delicate, and bears no slight degree 

 of resemblance to the skin of the human being. It is not to be 

 wondered at, that a structure so delicately organised as the one we 

 have been describing should be subject to disease. In the hog it is 

 peculiarly so j many of the most serious maladies to which he is 



