392 



EXCRETION 



The Stratum lucidum, a bright homogeneous membrane, consisting of 

 squamous cells closely arranged, in some of which a nucleus can be seen. 

 Stratum granulomm, consisting of one layer of flattened, fusiform, distinctly 

 nucleated cells. Stratum Malpighii or Rete mucosum consists of many strata 

 of cells. The deepest cells, placed immediately above the cutis vera, are 

 columnar with oval nuclei, succeeded by a number of layers of more or less 



FIG. 305. Vertical Section of Skin. A, Sebaceous gland opening into hair follicle; B, mus- 

 cular fibers; C, sudoriferous or sweat gland; D, subcutaneous fat; E, fundus of hair-follicle, 

 with hair- papillae. (Klein.) 



polyhedral cells with spherical nuclei; the more superficial layers are con- 

 siderably flattened. The deeper surface of the rete mucosum is accurately 

 adapted to the papillae 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 connected by processes, and thus form 

 prickle cells, figure 28. The pigment of the skin, in the deeper cells of rete 

 mucosum, causes the various tints observed in different individuals and differ- 

 ent races. The epidermis maintains its thickness in spite of the constant wear 



