214 GENERAL ANATOMY. 



would rather appear, that the pigment results from coloured 

 globules, disseminated through the corpus mucosum. 



The mucous body is not only more coloured, it is also 

 thicker in the negro, than in other races, and its thickness in 

 the latter is in direct proportion to its colour; thus, it is so 

 extremely thin in the white man, that its very existence has 

 been doubted. It is still thinner and so liquid in albinos, that 

 the action of the sun easily vesicates their skins, while in the 

 negro it is with difficulty that epispastics produce that effect. 



The colouring matter of the skin is very analogous to that 

 of the blood; it appears to be secreted from that humour and 

 to pass from the vessels of the surface of the dermis into the 

 mucous body, where it is in a kind of imbibition. Various mor- 

 bid phenomena induce a belief that it is continually renewed 

 there, by an unceasing deposition and absorption. Beddoes 

 and Fourcroy have observed by experiment, that the negro 

 skin plunged into water, impregnated with the vapour of 

 chlorine, becomes white, and in a few days resumes its black 

 colour in all its intensity. The chemical observations of Davy, 

 Coli and others have demonstrated that, which Blumenbach 

 had long before asserted, viz: that the pigment of the skin is 

 chiefly formed of carbon. 



The use of the pigment in the coloured races, appears to be, 

 to defend the skin against the rubefacient effect of the rays of 

 the sun, commonly called a coup de soleil.* 



304. The epidermis or cuticle, epidermis, cuticiilaj is a 

 distinct, though thin layer of the skin, which forms a kind of 

 dry and defensive varnish on its surface. The free or super- 

 ficial surface of this membrane, which is also that of the skin, 



* See Philosoph. Transact, ann. 1821, I. On the black rete mucosum, &c. 

 by Sir Ed. Home. 



f H. Fabricio, de totius animalis integumentis, ac primo de cuticula, et Vs 

 quae supra cuticulam sunt, in oper omn. Ludwig de cuticuld. Lipsiz, 1739. 

 Meckel, he. cit et Nouvelles observations sur les rtpiderme. Mem. de 1'acad. 

 roy. des sc. de Berlin, ann. 1757. Monro, sen. de cuticuld humana, oratio, 

 in works. Edinb. 1781. J. Th. Klinkosch et Hermann, de vera naturae cu- 

 ticula ejusque regeneratime. Prag-ac, 1775. B. Mojon, Sulf epidermide, etc, 

 Genao, 1815. 



