260 R E M A R K S o n t h e
c a u s e s texture, are likewife coloured blackilh. Meckel fufpedts, that the-
e t i e s blueilh liquor which colours the medullary fubftance o f the brain»
and fo eafily evaporates in negroes, contributes towards the dark
complexion of the mucous membrane o f the cuticle, being fer
creted by the cutaneous nerves into the vifcous reticular fub-
Itance,
But let us now inveltigate the caufes o f this phenomenon in ne.-
groes; we have already indicated the three molt ltriking caufes..,;
the expofure to the air, is undoubtedly, one o f the molt powerful,:
for do we not fee this daily proved in. our own climate;, our-ladies,,
and other people who are little expofed to the aftion o f the air, have
a fair complexion ; whereas the. common labourers are brown and
-tawny; nay our bodies furnilh us: withfufficient proofs.; thofe parts
which are conltantly covered, are fair and delicate,. but the hands
being conltantly expoled to the adtion, o f the air, acquire a darker
hue. The negroes live in a climate which permits them to wear
little or no covering at a l l ; accordingly,, we really find all. the ne-
groes naked, or very ilightly covered, which undoubtedly mult in-
creafe 'the black colour o f their Ikin. Th e Taheiteans, the
fairelt o f all the illanders in the South Sea, go almolt conltantly
dreffed and covered. T h e inhabitants o f Tanna, New Caledonia,,
and Mallicollo, on the contrary are always naked, and expofed to
the air,, and therefore infinitely blacker than the firlt.
T h e
IT U M A N S P E C l E S. 261
T h e operation of the Sun is undoubtedly another great caufe of the c a u s e s
- ■ ■ ■ '. ' . H f l ... . . O F V A R I -
d’ark hue in negroes; we find that nations in the fame proportion, EXIESp
as they approach the equator, likewife become darker coloured;
however, this oblervation is not quite uniyerfal, and ought: to be
modified under many circumltances. Inhabitants of illands are fel-
dom lo black as thofe o f great continents; in Africa, between the
tropics, the Ealterly winds prevail the m oll; and as in Abyffi—
nia thefe winds come over a large ocean, where they are mitigated
and cooled in their paffage, the inhabitants o f ' that country
are not. fo black as thofe about Senegal; which is fituated- in the
broadeft part of Africa,, and where the Eafterly wind having pafied
over the burning fands o f the immenfe continent, is become infinitely
more fiery and parching than in any other part. A higher expedite
above the furface o f the fea, makes, a great difference in the
temperature o f the air; the inhabitants o f Quito in Peru, though
living under the line, are by no means black or fwarthy. The vicinity
of the fea, and its refrelhing and- gently fanning breezes,
• contribute greatly to mitigate the power, o f a tropical-fun. This
caufe cannot be applied to- the difference-of colour in the Taheiteaas
and. the Mallicolefe, as both nations enjoy the fame advantage.
But the peculiar modes of living likewife,. Itrongly co-operate with
the above caufes, in producing the many changes o f colour in the
human fpecies. The Taheiteans are conltantly, cleanly, and. prastile