132 APPENDAGES OF THE SKIN. 



of the fluid; a variety of tumors of varied size and charac- 

 ter, as the steotoma, atheroma, meliceris, &c., or a fatty, a 

 pulpy, and a honey-like tumor; and, finally, inflammation 

 in all its various forms. 



APPENDAGES OP THE SKIN. 



The appendages of the skin consist of the hairs and 

 nails, which are modifications of the cuticle. 



The hairs (Fig. 19) present differences, according to 

 their situation, in length, fineness, delicacy, quantity, 

 size, and color. They differ according to races, being 

 long, fine, thick, and often curled, in the Caucasian and 

 Malay, fine and thin in the American, short and coarse 

 in the Mongolian, and crisped and woolly in the Ethio- 

 pian. They vary also with age and sex, being finer in 

 the young than in the old, and in the female than in the 

 male. 



Each hair is composed of a bulb and stem. The bulb 

 is simply a reflection of the skin, termed the follicle, con- 

 taining a conical pulpy substance called the papilla. The 

 follicle is ovoid in shape, and lined by the involuted cuticle ; 

 it is embedded in the subcutaneous, adipose, and cellular 

 structure, and is highly vascular and sensitive. The pa- 

 pilla is the part of the bulb generating the hair; from its 

 vessels, lymph is poured out containing cell germs; these 

 grow into cells with nuclei, which elongate and become 

 condensed into scales, overlapping each other, and form- 

 ing the cortex or outer surface of the hair. 



The hair lengthens by fresh successive additions from 

 the papilla, one beneath the other, constantly repeated, 

 as long as it continues to grow. 



The interior of the hair, called the medulla, has its cells 

 less condensed than the outer, and, on a transverse sec- 

 tion, gives the appearance of a cell-tube. 



Hair can be split, and of itself separates into filaments. 

 Pigment granules are found in the cells of the bulb, on 

 which the color depends; and into the follicle the ducts 

 of one or more of the sebaceous glands open and discharge 



