194 



The Descent of Man. 



Part 1. 



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 origin- 

 ally 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 some- 

 what liable to tropical fevers, after having resided for some time 

 in a colder climate. 00 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 

 Demerara during 1837, Dr. Blair found that the death-rate of the 

 immigrants was proportional to the latitude of the country 

 whence they had come. With the negro the immunity, as far as 

 it is the result of acclimatisation, implies exposure during a 

 prodigious length of time ; for the aborigines of tropical America 

 who have resided there from time immemorial, are not exempt 

 from yellow fever; and the Eev. H. B. Tristram states, that 

 there are districts in Northern Africa which the native inhabit- 

 ants are compelled annually to leave, though the negroes can 

 remain with safety. 



That the immunity of the negro is in any degree correlated 

 with the colour of his skin is a mere conjecture : it may be 

 correlated with some difference in his blood, nervous system, or 

 other tissues. Nevertheless, from the facts above alluded to, and 

 from some connection apparently existing between complexion 

 and a tendency to consumption, the conjecture seemed to me 

 not improbable. Consequently I endeavoured, with but little 

 success, 61 to ascertain how far it holds good. The late Dr. 



60 Quatrefages, ' Unite de 1'Espece 

 Surname,' 1861, p. 205. Waitz, 

 ' Introduct. to Anthropology,' trans- 

 late vol. i. 1863, p. 124. Living- 

 stone gives analogous cases in his 

 ' Travels.' 



In the spring of 1SG2 I ob- 

 tained permission from the Director- 

 General of the Medical department 

 of the Army, to transmit to the 

 surgeons of the various regiments 

 on foreign service a blank tabic, 

 with the following appended re- 

 marks, but 1 have received no re- 

 turns. " As several well-marked 

 " cases have been recorded with 

 " our domestic animals of a relation 

 " between the colour of the dermal 

 " appendages aud the constitution ; 

 " and it being notorious that there 



" is some limited degree of relation 

 " between the colour of the races of 

 " man and the climate inhabited by 

 " them ; the following investiga- 

 " tion seems worth consideration. 

 ' ; Namely, whether there is any re- 

 " hit ion in Europeans between the 

 colour of their hair, and their 

 liability to the diseases of tropical 

 countries. If the surgeons of the 

 several regiments, when stationed 

 in unhealthy tropical districts, 

 would be so good as first to count, 

 as a standard of comparison, how 

 manv men, in the force whence 

 the sick are drawn, have dark 

 and light-coloured hair, and hair 

 " of intermediate or doubtful tints ; 

 " and if a similar account were 

 " kept by the same medical gentle« 



