OF THE SKIN IN GENERAL. 



303. The pigment of the skin 1 ' is chiefly seated in the 

 corpus mucosum and particularly in its middle layer, but the 

 external surface of the dermis and the internal one of the epi- 

 dermis, also partly partake of it. Anatomists prior to Mal- 

 pighi, arid some even since, place its seat in these two mem- 

 branes, particularly in the latter. The colouring matter exists 

 in men of every race, albinos excepted. It is only in the 

 negro, however, that it can be distinguished, clearly, from 

 the rest of the skin. Malpighi had only announced, that the 

 colour of the skin had its seat in the rete mucosum; Littre had 

 tried, but in vain, to obtain the colouring matter, separately, 

 by submitting the negro skin to maceration, in order to swell 

 the mucous body, and thus to separate the epidermis from the 

 dermis. Although the corpus mucosum is soft and liquefia- 

 ble, we can succeed in separating from the skin of the negro 

 scrotum considerable portions of the coloured mucous body 

 in the form of a continuous independent membrane, separate 

 from the epidermis. Most generally, however, and I have 

 often tried the experiment, the maceration separates from the 

 dermis, which remains but very slightly coloured, the epider- 

 mis and corpus mucosum united and coloured; it is only with 

 great difficulty, that we can afterwards separate the mucous 

 body in the form of a membrane. If the maceration be con- 

 tinued in a small quantity of water, and the experiment be 

 made on the skin of the scrotum, a deeply coloured part, the 

 mucous body in resolving itself into a sort of mucosity, tinges 

 the water and finally deposits at the bottom of the vase, an 

 impalpable brown powder. Gautier has assigned, as the spe- 

 cial seat of the colouring matter, the middle layer of the corpus 

 mucosum, which he describes under the name of gem?nules, 

 as an undulated layer, which, with a single one of its turns, 

 would cover each one of the double furrowed lines of the der- 

 mis, of the palm of the hand, and the sole of the foot. It 



* B. S. Albinus. De sede et causa coloris cefhiopum etc. homin, etc. 

 LugtL-Bat. 1737, et Annot. lib. i. cap. ii. Meckel, loc. cit. S. T. Scem- 

 mering 1 , Uelter die korperliche vcrschie.denheit des negers vom europaer. 



