Malphigi, an eminent Italian physician, of the last century, was the first person who discovered that the skin was divided into three lamina, or parts; the _Cuticle_, the _true skin_, and a certain coagulated substance situated between both, which he distinguished by the title of _Mucosum Corpus_; a title retained by anatomists to the present day: which coagulated substance adhered so firmly to the _Cuticle_, as, in all former anatomical preparations, to have come off with it, and, from this circumstance to have led the ancient anatomists to believe, that there were but two lamina, or divisible portions in the human skin. This discovery was sufficient to ascertain the point in question: for it appeared afterwards that the _Cuticle_, when divided according to this discovery from the other lamina, was semi-transparent; that the cuticle of the blackest negroe was of the same transparency and colour, as that of the purest white; and hence, the _true skins_ of both being invariably the same, that the _mucosum corpus_ was the seat of colour. This has been farther confirmed by all subsequent anatomical experiments, by which it appears, that, whatever is the colour of this intermediate coagulated substance, nearly the same is the apparent colour of the upper surface of the skin. Neither can it be otherwise; for the _Cuticle_, from its transparency, must necessarily transmit the colour of the substance beneath it, in the same manner, though not in the same degree, as the _cornea_ transmits the colour of the _iris_ of the eye. This transparency is a matter of ocular demonstration in white people. It is conspicuous in every blush; for no one can imagine, that the cuticle becomes red, as often as this happens: nor is it less discoverable in the veins, which are so easy to be discerned; for no one can suppose, that the blue streaks, which he constantly sees in the fairest complexions, are painted, as it were, on the surface of the upper skin. From these, and a variety of other observations[081], no maxim is more true in physiology, than that _on the mucosum corpus depends the colour of the human body_; or, in other words, that the _mucosum corpus_ being of a different colour in different inhabitants of the globe, and appearing through the cuticle or upper surface of the skin, gives them that various appearance, which strikes us so forcibly in contemplating the human race.