SECT. 43-] 



EPIDERMIS. 



87 



fitted to all the subjacent elevations and depressions; and on this 

 account its inner surface is an exact mould of the external surface 

 of the corium, and in such a manner, that where the latter presents 

 an elevation, the former exhibits a conformable depression, and 

 vice versa. Upon the external surface, also, of the epidermis, the 

 form of the corium is repeated, to a certain extent, inasmuch as 

 the more important elevations and depressions, such as the ridges 



Fig. 38. 



Umler surface of the epidermis, detached by maceration from the palm, showing the double 

 rows of depressions, in which the papills have been lodged, with the sudoriferous ducts 

 extracted out of the cutis. After Todd and Bowman. 



of the palm of the hand and of the sole of the foot, the furrows 

 at the joints, the muscular insertions, etc., are expressed on it — 

 the latter even more strongly; while the papilla? occasion either 

 no discernible elevation, or scarcely any. 



The epidermis is composed of two layers, which differ from each 

 other in structure and chemical composition, and are separated by 

 a tolerably distinct boundary line, viz., the mucous layer and the 

 horny layer. 



k 43. The mucous layer, stratum Malpighii, rete, or mucus Mal- 

 pighii of many authors, is the inner undulating portion of the 

 epidermis, immediately adjoining the corium, which in many 

 places, even with the naked eve, can be distinguished by its white 



