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of the more superficial layers are considerably flattened. The deeper 

 surface of the rete mucosum is accurately adapted to the papillas of the 

 true skin, being, as it were, moulded on them. It is very constant in 

 thickness in all parts of the skin. The cells of the middle layers of 

 the stratum Malpighii are almost all connected by processes, and thus 

 form prickle cells (fig. 35). The pigment of the skin, the varying quan- 

 tity of which causes the various tints observed in different individuals 

 and different races, is contained in the deeper cells of rete mucosum; 

 the pigmented cells as they approach the free surface gradually losing 

 their color. Epidermis maintains its thickness in spite of the constant 



Fig. 310. Vertical section of the epidermis of the prepuce, a, stratum corneum, of very few- 

 layers, the stratum lucidum and stratum granulosum not being distinctly represented; 6, c, d, and e, 

 the layers of the stratum Malpighii. a certain number of the cells in layers d and e showing signs of 

 segmentation; layer c consists chiefly of prickle or ridge and furrow cells; /, basement membrane; 

 g, cells in cutis vera. (Cadiat.) 



wear and tear to which it is subjected. The columnar cells of the deep- 

 est layer of the rete mucosum elongate, and their nuclei divide into two 

 (fig. 310, e). Lastly the upper part of the cell divides from the lower; 

 thus from a long columnar cell are produced a polyhedral cell and a 

 short columnar cell : the latter elongates and the process is repeated. 

 The polyhedral cells thus formed are pushed up toward the free surface 

 by the production of fresh ones beneath them, and become flattened 

 from pressure : they also become gradually horny by evaporation and 

 transformation of their protoplasm into keratin, till at last by rubbing 

 in ordinary wear and tear they are detached as dry horny scales at the 

 free surface. There is thus a constant production of fresh cells in the 



