138 SPECIAL HISTOLOGY. 



§ 44. 



The thickness of the epidermis as a whole, varies exceedingly, 

 depending especially upon that of the horny layer. It 

 measures : 



upon the chin, the cheeks, and brow, in the external 

 auditory passages, and upon the eyelids: 



upon the bridge of the nose, on the breast and nipple 

 in the female, on the back of the toes and fingers, 

 upon the neck and back, on the inner and outer 

 side of the thigh, on the scrotum and the labia 

 minora : 



on the edge of the eyelids, on the male chest and 

 nipple, the hairy scalp, the chin, penis, prepuce, 

 and glans penis: 



on the red external parts of the lips, on the back of 

 the hand : 



on the flexor side of the fingers and toes : 



on the palm : and — 



on the sole of the foot, in which two latter localities 

 the variations are greatest, independently of the 

 circumstance, that in the furrows and at the joints 

 the skin is thinner than elsewhere. 



With regard to the proportionate thickness of the horny 

 and mucous layers I find, in some localities, that the latter is 

 constantly thicker than the former; i. e., in all parts of the 

 face, in the hairy scalp, in the penis, the glans, the scrotum, 

 the nipple, and the skin of the thorax in man ; in the labia 

 majora and minora, on the back and neck. Here the mucous 

 layer is 3 — 6 times, or 2 — 3 times as thick as the horny layer, 

 according as its thickness is measured from the bases or from 

 the points of the papillce; in a few of the localities mentioned, 

 however, the stratum MaJpighii is, in its thinnest parts, of the 

 same thickness as the epidermis, as in the glans. In the rest 

 of the body, both layers are either equal in thickness, as in the 

 external auditory passage, and here and there upon the flexor 

 side of the first two sections of the extremities, or the horny 

 layer is 2 to 5 times thicker than the mucous, and in the 

 thickest places even 10 to 12 times as thick. 



