38 SPECIAL ANATOMY. 



The unevenness of the epidermis depends upon that of the corium which is 

 found underneath it. There are elevations, grooves and fossae, from the last 

 of which hair, sweat or fat, with which the cuticle is constantly saturated, ap- 

 pears. By boiling, the epidermis easily separates, especially in the palm of 

 the hand or sole of the foot, into an external and an internal layer. The in- 

 ternal layer (rete Malpighii), improperly regarded as a peculiar membrane, is 

 softer, but not essentially different from the external layer, into which, by de- 

 grees, it passes ; its reteform appearance arises from rearing out the nervous 

 papillae of the corium, otherwise it is granular, whilst the external layer ap- 

 pears striated. In the Negro the rete Mdlpighii is, likewise, nothing else but 

 this internal layer with black pigment adherent to it. 



2. Corium, true skin, is a soft, at the same time strong, dense, and very ex- 

 tensible organ, of a red colour and variable strength ; thickest in the surfaces 

 of the foot and hand, stronger in the male than in the female, and very deli- 

 cate on the eyelid and the glans penis. Upon its external free surface we 

 observe folds, especially in places which are subject to extension (in the palm 

 of the hand, upon the dorsum of the fingers, on the foreskin). Other folds 

 are formed by means of the muscles, which act upon the skin (e. g., on the 

 forehead). These, in time, remain constantly (as wrinkles), like the folds 

 which arise upon the abdomen, in consequence of the greater extension, after 

 pregnancy and dropsy ; in old age they arise from the loss of the fat. 



The skin is moveable by proper cutaneous muscles (in man on 

 the face and in the hand only) ; by a very fatty, as well as ex- 

 panded uniting tissue in the form of a membrane (fascia super- 

 ficialis). See Myology. 



The external skin is both an organ of touch and of secretion, 

 by means of the tactile. papillae, arranged in rows, upon the linear 

 elevations, the sweat and sebaceous glands, and the glandules of 

 the hair follicles found in the depressions between them. 



a. Tactile, sensitive papillae, Papillce corii, consist of closely compressed 

 fasciculi of uniting tissue, in the interior of which a vascular and nervous loop 

 passes. (The nerves do not terminate like a hair-pencil or club, but are re- 

 flected, and return to the surface of the skin.) The Papillae lie in the upper- 

 most layer of the Corium, covered by the Epidermis, which fills up, partly or 

 entirely, the depressions between them, and therefore gives to the skin either 

 a grooved or even appearance. We distinguish filamentous and club-shaped 

 papillae. The finer they are, so much the more crowded they stand, and the 

 more sensitive is the skin (e. g.. on the inner surfaces of the fingers, in the 

 sole of the foot, on the nipple, the lips, glans penis, and clitoris). 



b. Sebaceous follicles, folliculi sebacei, spread over the whole surface of the 

 body (with the exception of the palm and sole), found especially at the points 

 of transition of the external skin into the mucous membrane. The larger 

 open immediately upon the skin, namely in places devoid of hair (e. g., the 

 glans penis, the nymphse) ; they do not consist, probably, of simple follicles. 

 but must be enumerated with the racemose glands ; the smallest lie in pairs 

 on either side of a hair follicle, and open immediately into it. These last 

 consist of small fat cells which lie dispersed in round heaps of 0*007 of a 

 line in diameter. They contain an oil, the grease of the skin, sebum cutaneum, 

 which makes the skin and hair pliable. To the glands of the hair follicles 

 belong also, probably, Eichhorn's lymph spaces of the cutis. 



