VISCERAL ANATOMY. I67 



THE SENSE OF TOUCH. 



The special sense of touch is located in the skin, being more 

 marked in the lips and extremities. 



THE SKIN. 



The skin is the outer, enveloping membrane of the body, and 

 continuous with the outer hmits of the internal mucous mem- 

 branes. It is divided into the derma or cutis vera, internally, and 

 the epide?'??iis, externally. 



The Derma forms the greater part of the thickness of the skin, 

 being continuous with the subcutaneous connective tissue, intern- 

 ally, and the epidermis, externally, where it contains little eleva- 

 ions, the papillcE. It is composed internally of loose meshed 

 tissue, the corium, and externally of the papilLF, arranged in 

 parallel rows about yiy- of an inch in length. 



The Epidermis, or cuticle, lying upon the derma, is more or 

 less pigmented, and consists of an internal deep layer or re/e 

 mucosum, containing soft pigment cells and a superficial or hortiy 

 layer of condensed, horny, flattened cells. 



The Appendages of the Skin are the hairs, sudoriferous 

 and sebaceous glands and horny parts. 



The Hairs. 



The hairs are modifications of skin, and are divided into 

 the hair proper, forming the coat, and horse hair, long and flow- 

 ing, found in \h^ forelock, mane, tail, eyelashes, lips 2ind fetlock. 



Structure. 



Hairs consist of a free, projecting portion, the shaft, of three 

 layers, an external of flattened epidermal scales, a middle or 

 cortical of narrow, epithelial lamellae, pigment and air globules, 

 and an internal or ?nedullory of rectangular cells with fat and air 

 globules ; a root lying imbedded in the skin, in an involution, the 

 hair follicle with external and internal sheaths and resting on the 

 papilla, from which it takes its nutrition and growth. 



The Sudoriferous Glands are attached to the skin, consisting 

 of a curled tubule lying in the corium and a spiral duct passing 

 up through the derma and epidermis, Hned with epithehum. 

 Their function is the regulation of animal heat, and also are con- 

 nected with excretion. 



