THE EPIDERMIS. 33 



cover a red cloth with a piece of milk-glass, we have the flesh 

 color presented to our eyes, and the thicker the piece of glass 

 selected, the lighter the tone will be. It is thus with the 

 complexions of Europeans. The corium during life appears 

 red, in consequence of its extreme richness in blood ; the 

 epidermis is semi-transparent, whitish or whitish- yellow. 

 The thinner the latter, the redder the color (lips, cheeks) ; 

 the thicker the cell covering (the foot-sole, frequently the palm 

 of the hand also), the paler the surface of the body. 



In the skin of the dark human races, that of the negro, the 

 nuclei in the deeper layers of the epidermis are diffuse 

 brown ; the cell bodies are also somewhat darker, and may 

 also contain pigment molecules. In the darker portions of the 

 bodies of the light races (the nipple and its areola) the same 

 condition prevails. The coloring matter here conceals the 

 red of the cutis. 



All stratified epithelia. as we already know from what has 

 preceded, are of a perishable nature. Millions of the super- 

 ficial cells fall off daily, from rubbing, pressure, etc. The 

 new formation takes place at the deepest layer, by a process 

 of division. Between the latter cell layers, finally, immi- 

 grated lymphoid cells may also be met with. 



The second form of epithelial tissue, the cylindrical, be- 

 longs to the digestive apparatus, from the entrance to the 

 stomach to near the anus, likewise to the ducts of the liver 

 and pancreas, the ducts of the lacteal and lachrymal glands, 

 and also some portions of the sexual apparatus. 



We there (Fig. 6, b, 14, a) meet, as a rule, with a single row of 

 narrow, vertically elongated cells, with a sometimes super- 

 ficially, sometimes more deeply lying nucleus, which contains 

 a nucleolus. A thin layer of cement substance unites our 

 cells, which, seen from above (Fig. 14, b) present a fine mosaic. 

 Their height and breadth vary. In the human small intes- 

 tine, the former is 0.0182 to 0.027, the latter 0.0057 to 0.009 mm - 

 The lateral walls show an envelope ; the free base may present 

 naked protoplasma, as in the stomach ; it may, also, how- 

 ever, show a different character. This is the case in the 

 2* 



