tions, 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.

As this can be incontrovertibly ascertained, it is evident, that
whatever causes cooperate in producing this different appearance, they
produce it by acting upon the _mucosum corpus_, which, from the
almost incredible manner in which the cuticle[082] is perforated, is as
accessible as the cuticle itself. These causes are probably those
various qualities of things, which, combined with the influence of the
sun, contribute to form what we call _climate_. For when any person
considers, that the mucous