52 



STRUCTURE OF THE SHEEP 



very dark faces and iegs, the skin, if healthy, is bright pink or 

 cherry in color, but in the exceptions noted and in sheep bearing 

 dark wool it is often bluish and in some cases almost black. In 

 nearly all breeds the naked skin around the muzzle is black. 



The skin ^ consists of the cutis or skin proper and its epidermal 

 appendages, the hair, wool, hoofs, and horns. The cutis is com- 

 posed of two layers, the epidermis, a superficial epithelial layer. 



Fig. 23. — Diagrammatic section of skin, showing (a) shaft of hair arising from the 

 follicle, (6) sebaceous glands and (c) sweat glands. (From "Structure of the Wool Fi- 

 bre," Bowman. Courtesy of The Macmillan Co.) 



and the derma or corium, a deep, connective-tissue layer, which is 

 supplied with blood vessels and nerves and contains glands aiid 

 hair-follicles. 



The hair-follicle is a modification of the skin and, according 

 to Sisson, may be regarded as an invagination or a folding-inward 

 of the epidermis. It seems, however, that the follicles of the larger 

 human hairs contain both epidermal and dermal elements * (Fig. 

 23). 



The hair originates at the bottom or base of the hair-follicle 

 from an extension of the corium called a papilla, to which the 



"See Sisson's "Veterinary Anatomy," 1911. 

 * Bailey, "Text Book of Histology," 1916. 



