()F THK SKIN 



ni 



15. EPIDERMIS. 



§ 40. 



The corium is everywhere covered by a seinitransparent 

 membrane formed wholly of cells, and containing neither 

 vessels nor nerves, — the epidermis, which applies itself exactly 

 to all the elevations and depressions, and which accordingly upon 



Fig. 55 A. 



its inner surface presents an exact cast of the outer surface of 

 the corium, the convexities and concavities of course being 

 reversed. Upon its outer surface, also, the epidermis, to some 

 extent, represents the form of the corium, since the more marked 

 elevations and depressions, such as the ridges of the palm of 

 the hand and of the sole of the foot, the folds at the joints, 

 muscular insertions, &c. are expressed in it, — the latter even 



Fig. 55 A. Surface of the palm, from within : a, ridge answering to the groove 

 between the ridges of the cutis ; b, a similar one corresponding with the cleft between 

 the rows of papillae ; c, sweat ducts ; d, broader points of insertion of these into the 

 epidermis ; e, depressions for the simple and compound papillae. 



