88 



EPIDERMIS. 



[sect. 43. 



Fig. 39. 



or various shades of brown colour from the horny layer, and is 

 characterised by its soft, easily destructible, peculiarly arranged, 

 small cells. 



The form of these cells, as well as their arrangement, is not 



everywhere the same. The most 

 internal, which lie immediately upon 

 the free surface of the corium in the 

 form of a simple layer, without in- 

 termingled nuclei or semi-fluid sub- 

 stance, are elongated, like columnar 

 epithelial cells, and stand perpendi- 

 cularly on the corium ; their length 

 amounts to from o , oo33'" ^° o - oo6", 

 their breadth, 00025'" to o - oo3"\ 



Upon these immediately follow, 

 in most regions, oblong or even 

 round cells, from o'003'" to o - oo4'", 

 in several layers ; but in some places, 

 as on the hand and foot, at the 

 Perpendicular section through the skin of a free border of the eye-lids, on the 



negro (from the leg), a. Papilla;; b. deepest „,.,„„„„ l nv pr o.f tViP nnila nnrl Vinir 



intensely coloured layer of elongated cells of "1UCOUS ldyer OI lllti lldllS dllU nail, 



the stratum mucosum ; c. upper layer of the ar[p u vn arlf ] Pveri +l irP p lavprs of 



stratum mucosum; d. horny layer. Magni- UI1L > lw(J J ciIlu evt;u "II ^^ Idyerb OI 



ned 100 diameters. likewise elongated and perpendicu- 



larly arranged elements, are interposed between the round and 

 the elongated cells, so that the mucous layer, on account of the 

 numerous perpendicularly disposed layers- of cells, presents, under 

 a higher magnifying power, a striated appearance. This condition 

 is the more conspicuous, since the other elements of the mucous 

 layer, the further they are traced from the first round cells out- 

 wardly, become thinner in another direction, viz., are flattened 

 horizontally ; and, at length, in the uppermost layers, are converted 

 into vesicles, from o - oo6'" to o - oi6" in breadth, and from o - oo2'" 

 to o - oo8"' in thickness. At the same time, in consequence of 

 mutual pressure, they take on a more or less evident polygonal 

 form, which can also be perceived in isolated cells. 



All the cells of the mucous layer agree essentially in their 

 structure, and are nucleated vesicles entirely filled with fluid. 

 Their membrane is pale, in the smallest often difficult to demon- 

 strate, often quite evident, always delicate, and though stouter in 

 the larger cells, yet not to be compared to that of the cells of the 

 horny layer. Their contents are never entirely fluid, although, with 

 the exception of coloured epidermis (see below), they never normally 



