The Descent of Man

negro seems to be partly inherent, depending
on some unknown peculiarity of constitution,
and partly the result of acclimatisation. Pouchet
(59. 'The Plurality of the Human Race' (translat.),
1864, p. 60.) states that the negro regiments
recruited near the Soudan, and borrowed
from the Viceroy of Egypt for the Mexican
war, escaped the yellow-fever almost equally
with the negroes originally brought from various
parts of Africa and accustomed to the
climate of the West Indies. That acclimatisation
plays a part, is shewn by the many cases in
which negroes have become somewhat liable to
tropical fevers, after having resided for some
time in a colder climate. (60. Quatrefages, 'Unite
de l'Espece Humaine,' 1861, p. 205. Waitz,
'Introduction to Anthropology,' translat., vol. i.
1863, p. 124. Livingstone gives analogous cases
in his 'Travels.') The nature of the climate under
which the white races have long resided, likewise
has some influence on them; for during
the fearful epidemic of yellow fever in Demera-