THE ANATOMY OF THE HOG 



in the mature animal. The heart is small, usually weighing 

 less than a pound. The kidneys are smooth and bean 

 shaped, about twice as long as broad. The bladder is thin 

 and has considerable capacity. 



The skin of the hog in the improved breeds varies in 

 character, and ranges in thickness from one to two milli- 

 meters (.04 — -.08 inch). The sebaceous glands in the skin, 

 according to Sisson, are small, and not so abundant as with 

 most other animals, while the sweat glands, to the contrary, 

 are large, yellow or brownish in color, and may often be 

 seen with the naked eye. The exterior layer of the skin is 

 much tougher and denser than with other domestic animals, 

 and contains many large pores. Numerous fine blood ves- 

 sels, capillaries and nerves extend through the delicate 

 under layer of skin. Referring to tlie quality of the skin, 

 Youatt states * that in some of the large, old breeds it is 

 thick, coarse, tough and almost as impenetrable, in compari- 

 son, as the hide of a rhinoceros ; while in many of the smaller 

 breeds, and particularly in those which have a considerable 

 admixture of Asiatic blood, and in the Chinese pigs them- 

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

 of resemblance to the skin of a human being. 



The hair of the hog is quite variable, according to the in- 

 dividual, or to the 

 part of the body on 

 which it grows. The 

 coarsest, heaviest 

 hairs are found 

 along the back over 

 the spine, and espe- 

 cially over the neck 

 and shoulders. 

 These hairs are 

 known as bristles, 

 and in the case of 

 male hogs, they 



Fig. 261.— "Some Individuals have coats of 

 curly hair." This is a Lincolnshire Curly Coated 

 pig, a British breed. 



* The Pig, 1847, p. 107. 



