VISCERAL ANATOMY. 167 



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 limits of the internal mucous mem- 

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

 the epidermis, 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- 

 tions, the papilla. It is composed internally of loose meshed 

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

 parallel rows about T -J^ 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 rete 

 mucosum, containing soft pigment cells and a superficial or horny 

 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 flowing, 

 found in the forelock, mane, tail, eyelashes, lips and fetlock. 



Structure. 



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

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

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

 and an internal or medullary 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, lined with epithelium. 

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

 nected with excretion. 



