THE INTEGUMENTS AND CLOTHING OF MAMMALIA. 



145 



Skin of Negro. 



THE INTEGUMENTS AND CLOTHING OF MAMMALIA. 



THE bodies of all Mammalia are invested with an external envelope, 

 more or less dense, more or less delicate, commonly denominated the 

 143 skin. The skin, however, is not a single sub- 



stance, but consists essentially of the dermis, cutis, 

 or corium, and a double epidermal tissue ; the 

 lowermost of which, or that in immediate contact 

 with the corium, when coloured by a mucous 

 pigment, has been termed rete mucosum. Fig. 

 143 represents the section of the skin of a Negro, 

 with a portion of the external and of the internal 

 cuticle, or epidermis, turned down; the latter is 

 stained with the pigmentum nigrum, and is the 

 rete mucosum of many anatomists. That the pig- 

 mentum nigrum does not always imbue, even when 

 secreted by the corium, the internal epidermis, is proved by several pre- 

 parations in the Royal College of Surgeons ; of one of which, the annexed 

 sketch (fig. 144), exhibiting a section of part of the in- 

 teguments of the Porpoise, is a representation. This 

 preparation shews the cuticle divided into two layers, 

 of which the external is, apparently, about to be cast 

 off. The internal, or that next the cutis, would appear 

 to be made up of fibres, passing perpendicularly to 

 the surface ; but that appearance is owing to the pre- 

 sence of innumerable canals for the reception of the 

 long villi of the corium. The pigmentum forms a thin 

 layer beneath this cuticle, but is not mixed with it, or 

 extended to the surface, so as to influence its colour.* 



In the skin of the abdomen of the bottle-nosed Whale (Delphinua 

 145 146 



Tursio, Fabr.), which is white, there is no apparent pigment, but the ex- 



* In the red-coloured legs of the Turkey, and other birds, the pigment forms a varnish beneath 

 the cuticle, as though a pencil, dipped in carmine, had spread a thin layer over the limb ; and it is as 

 easily washed away as if it had been thus laid on. 



VOL. I. 



