THE SKIN. 



437 



superficial or papillary and the deep or areolar layer. 

 The epiderm is composed of cells. The deepest are 

 columnar and present, in the colored races, numerous 

 pigment cells ; in the white races these are but few in 

 number and scattered. Gradually, in passing toward the 

 surface, the cells become flattened, lose their nuclei, be- 

 come changed in their chemical properties, and are dis- 



FIG. 192. SECTION OF THE SKIN. 



posed in strata of flat, scale-like cells, the outer layer of 

 which is constantly exfoliated. The true skin is sepa- 

 rated from the epiderm by a homogeneous basement mem- 

 brane which invests the papillary layer. The papillary 

 layer consists of papillae, each about T ^ T inch high, -^-^ 

 inch thick. They consist of a flbrous, skeletal structure, 

 supporting capillary vessels and nerves, and, in certain 

 localities, special nerve end-organs. The areolar layer is 



