c iUp. VII. 
THE RACES OF MAN. 
243 
°ccurred to Dr. Wells. 43 That negroes, and even mulat- 
tos, are almost completely exempt from the yellow- 
* 6 Ver, which is so destructive in tropical America, has 
* 0| ig been known. 44 They likewise escape to a large 
ex tent the fatal intermittent fevers that prevail along, 
at least, 2600 miles of the shores of Africa, and which 
annually cause one-fifth of the white settlers to die, and 
Mother fifth to return home invalided. 45 This immu- 
nity in -the negro seems to be partly inherent, de- 
pending on some unknown peculiarity of constitution, 
{| nd partly the result of acclimatisation. Pouchet 4C 
^ates that the negro regiments, borrowed from the 
Viceroy of Egypt for the Mexican war, which had been 
re cruited near the Soudan, escaped the yellow-fever 
nlniogt equally well with the negroes originally brought 
h'onr various parts of Africa, and accustomed to the 
Miniate of the West Indies. That acclimatisation plays 
a part is shewn by the many cases in which negroes, 
a tter having resided for some time in a colder climate, 
have become to a certain extent liable to tropical 
* 6v ers. 47 The nature of the climate under which the 
"'lute races have long resided, likewise has some in- 
^ hence on them; for during the fearful epidemic of 
yellow-fever in Demerara during 1837, Dr. Blair found 
^at the death-rate of the immigrants was proportional 
, . 3 See a pc per read before the Royal Soc. in ISIS, and published in 
k Essays in 1818. I have given an account ot Dr. Wells’ views in the 
historical Sketch (p. xvi) to my 1 Origin of Species.’ Various cases of 
- - correlated with constitutional peculiarities are given in my 
•v fc 
44 
U'iation of Animals under Domestication,’ vol. ii. p. 227, 335. 
16 See, for instance, Nott and Gliddon, * Types of Mankind,’ p. 68. 
Major Tulloeb, in a paper read before the Slatistieal Society, 
tail 20th, 1840, and given in the ‘ Athenaeum,' 1840, p. 353. 
1 The Plurality of the Human Race’ (translat.), 1864, p. 60. 
i - ' Quatrefages, ‘ Unite de i’Espece Humaine,’ 1861, p. 205. Waitz 
3t ’'Moduct. to Anthropology,’ translat. vol. i. 1863, p. 124. Living- 
»ne gives analogous cases in his ‘ Travels.’ 
R 2 
