THE SKIN AND ITS APPENDAGES. 



superficial fascia of the body or underlying structure, whatever that 

 may be. These strands are the retinacula cutis, and inclose in 

 their meshes masses of fatty tissue which form the pannicithis 

 adiposns. The latter varies greatly in thickness in different parts 

 of the body. The vertically arranged cords of connective tissue 

 are accompanied by blood-vessels, nerves, and the excretory ducts 

 of glands. 



Smooth muscle-fibers are also present in the skin, and around 

 the hair follicles are grouped into bundles. Nearly continuous 

 layers of smooth muscle tissue are found in the subcutaneous layer 

 of the scrotum (forming here the tunica dartos], in the perineum, 

 in the areolae of the mammae, etc. In the face and neck striated 

 muscle-fibers also extend outward into the corium. 



Even in the white race certain regions of the epidermis always 

 contain pigment as, for instance, the areolae and mammillae of the 



Processof _ 

 pigment 

 cell. 



Stratum 

 corneum. 



Pigment 

 -- cell with 

 two pro- 

 cesses. 



~ Pigmented 

 basal cell. 



Fig. 307. Cross-section of negro's skin, showing the intimate relationship of the 

 pigment cells of the corium to the basilar cells of the epidermis. The latter are more 

 deeply pigmented at their outer ends. The pigment granules may be traced into the 

 outermost layers of the stratum corneum ; X 5 2 5- 



mammary glands, the scrotum, labia majora, around the anus, etc. 

 In these regions the epithelial cells and the connective-tissue cells of 

 the pars papillaris eorii contain a variable number of small pigment 

 granules. The latter occur chiefly in the basal cells of the epider- 

 mis and diminish perceptibly in the cells of the overlying layers, so 

 that in those of the stratum corneum few, if any, are left. In 

 negroes and other colored races the deep pigmentation is due to a 

 similar distribution of the pigment granules in the entire epidermis ; 

 but even here the pigmentation decreases toward the surface, 

 although the uppermost cells of the stratum corneum always con- 

 tain some pigment. The nuclei of the cells are always free from the 

 coloring-matter. The question as to the origin of the pigment is 

 as yet unsolved. This much is known : that in those regions where 

 pigment is present certain branched and deeply pigmented connec- 



