Chap. VII. THE RACES OF MAN. 243 



occurred to Dr. Wells. 43 That negroes, and even mulat- 

 toes, are almost completely exempt from the yellow- 

 fever, which is so destructive in tropical America, has 

 long been known. 44 They likewise escape to a large 

 extent 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 

 another 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, 

 and partly the result of acclimatisation. Pouchet 46 

 states that the negro regiments, borrowed from the 

 Viceroy of Egypt for the Mexican war, which had been 

 recruited near the Soudan, escaped the yellow-fever 

 almost equally well 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, 

 after having resided for some time in a colder climate, 

 have become to a certain extent liable to tropical 

 fevers. 47 The nature of the climate under which the 

 white races have long resided, likewise has some in- 

 fluence on them ; for during the fearful epidemic of 

 yellow-fever in Demerara during 1837, Dr. Blair found 

 that the death-rate of the immigrants was proportional 



43 See a paper read before the Royal Soc. in 1813, and published in 

 his Essays in 1818. I have given an account of Dr. Wells' views in the 

 Historical Sketch (p. svi) to my ' Origin of Species/ Various cases of 

 colour correlated with constitutional peculiarities are given in my 

 ' Variation of Animals under Domestication,' vol. ii. p. 227, 335. 



44 See, for instance, Nott and Gliddon, ' Types of Mankind,' p. 68. 



45 Major Tulloch, in a paper read before the Statistical Society, 

 April 20th, 1840, and given in the ' Athenaeum,' 1840, p. 353. 



46 * The Plurality of the Human Race ' (translat.), 1864, p. 60. 



4 ' Quatrefages, ' Unite de l'Espece Humaine,' 1861, p. 205. Waitz, 

 'Introduct. to Anthropology,' translat. vol. i. 1863, p. 124. Living- 

 stone gives analogous cases in his ' Travels.' 



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