54 PHILOSOPHICAL TRANSACTIONS. [aNNO 1744. 



Hence the fonuation of the epidermis seems to be more easily shown, and more 

 completely deduced, than from any preparation of it in white people. For the 

 external lamella of it manifestly arises from the corpus reticulare, by the interven- 

 tion of the black fibrillae, which has been shown to pervade the inner lamellae of 

 the epidermis ; and this corpus reticulare itself arises from the subcutaneous nerves, 

 so nicely and accurately delineated by Eustachius. 



Prop. 4. — The Colour of Negroes does not proceed from any black Humour, or 

 fluid Parts contained in their Shins; for there is none such in any Part of their 

 Bodies, more than in white People. — It has been the generally received opinion, 

 since Malpighi's time, that the cause of the colour of negroes is a juice or fluid 

 of a black colour, which lies between the epidermis and cutis, in some aqueous 

 vessels, which serve to lubricate those parts. But Malpighi seems to propose this 

 rather as a probable opinion, to be more thoroughly examined, than as an esta- 

 blished one to be confided in. But this opinion needs only to be well and more 

 thoroughly considered, to be confrited : for if we consider the ill qualities, and 

 pernicious efl^ects to our bodies, of any such exalted sulphureous juices, no one 

 will imagine that any animal can live in health, with any such fluids in his body; 

 since all the fluids of the body constantly circulate, and communicate with each 

 other; for such sulphureous juices seem to be the cause of black tongues in acute 

 diseases, and of the blackness of gangrenes in some measure, which we know 

 soon prove fatal, unless removed. Besides, these juices must be secerned from 

 the blood, which seems to have no more disposition to turn black, in black than 

 in white people : and as these black juices lie in the skin, it is very probable that 

 they might often be exhaled, especially in sweating; and might leave the skin 

 destitute of its black colour, in some measure, at such times; which it never is, 

 but appears rather blacker at such times, than any other. And as this humour 

 must be secerned from the blood, and constantly exhaled and renewed again, it is 

 very likely that it would be often obstructed in its secretion, or altered in colour, 

 in some morbid cases, like the other humours, as well as evaporated sometimes ; 

 which however we never see it to be. 



But if there was any such thing as a black humour in the skins of negroes, no 

 doubt it might be drawn out by some means or other; but, though Dr. M. had 

 macerated the skins of negroes, and particularly the epidermis, in warm water, 

 which readily dissolves the juices of the body, yet he never could extract any black 

 juices from them, by any such maceration, or even by a more powerful expression ; 

 no more than Mr. Littre, as is related, could do, by more powerful dissolvents. 

 Nothing seems more likely to extract this supposed black juice, than the action 

 of fire, or cantharides, on the vessels which contain it, which abrade and tear the 

 vessels and fibres of both the cuticle and corpus reticulare from the skin, but leave 

 them both as black as ever they seem to have been, though they would doubtless 



