CHAPTER XVII. 



THE SKIN AND ITS ADNEXA. 



THE SKIN. 



WE recognize in the skin three layers of tissue : 

 i, an outer, epithelial layer, the epidermis ; beneath 

 this, 2, a layer of quite firm and dense connective 

 tissue, the corium true skin, cutis vera, or derma ; 

 3, a layer of looser connective tissue, the subcu- 

 taneous tissue, which, merging into the corium, 

 serves to bind it to the underlying parts. The skin 

 is variously modified in structure in different parts 

 of the body, corresponding to the different condi- 

 tions of exposure and wear to which it is subjected, 

 and to form certain supplementary structures, such 

 as the hair, nails, etc. ; and contains various sensory 

 and secretory structures. 



In the epidermis we recognize two tolerably dis- 

 tinct layers of cells : I, an outer or horny layer, con- 

 sisting of very thin, transparent, tough, scale-like 

 cells, which present, for the most part, no nuclei, 

 and are packed closely together ; 2, an inner layer, 

 the so-called mucous or Malpighian layer, consisting 

 of larger and smaller nucleated cells of varying 



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