INSECTS AND DISEASE. 651 



work. (See also p. 416 of Dr. Johnson's work, and p. 15 of Dr. W. J. 

 Evans on "Endemic Fevers of West Indies," 1837.) 



Dr. Oldham (" What is Malaria ? " p. 172) tells us that the Jeevas of 

 the Punjaub, employed in fishing and catching wild-fowl, spend the 

 whole night in their boats, under the reeds of the marshes, "unharmed 

 in the midst of malaria " ; but they are wrapped from " head to foot " 

 in a peculiar costume that completely envelops them, and which they 

 always put on at sunset ; and, moreover, a smoldering fire is kept up 

 in the boat. 



It is almost needless to add that, while these nets, curtains, etc., can 

 hardly be conceived to intercept marsh-air, they certainly can and do 

 intercept and protect from mosquitoes. 



18. Malaria spares no age, but it affects infants much less fre- 

 quently than adults. 



The child in utero has even been alleged to suffer from asrue when 

 its mother was affected : she has felt it, as she supposed, shivering or 

 executing spasmodic movements during the paroxysm, and such in- 

 fants have been born with enlarged spleens. Nevertheless, it is a mat- 

 ter of daily observation that the sucking infant is less liable to malarial 

 disease than older children and adults. 



Young infants, however, be it remembered, are usually carefully 

 housed, and in summer their beds or cradles are generally provided 

 with mosquito-curtains to keep off house-flies, and they may thus be pro- 

 tected from mosquital inoculation. Furthermore, since the human in- 

 fant, in savage life, and without the artificial protection of gnat-cur- 

 tains, would be presumably helplessly exposed to mosquito-bites, it 

 would not surprise us if Nature had given the infant some inbred ec- 

 centricity by which the inoculations would be rendered harmless ; just 

 as the bite of the African tsetse-&y, which will destroy cows and oxen, 

 is perfectly harmless when inflicted upon the sucking calf, as attested 

 by Burton, Livingstone, and Stanley. 



19. " Of all human races the white is most susceptible to marsh- 

 fevers, the black least so." 



The black man, however, is not entirely exempt, and is probably 

 more secure in his native clime than in the United States and other 

 civilized countries to which he has been imported. Acclimatization is 

 alleged to be the proper explanation of this exemption. The negro, 

 it is said, is born in a country where he is obliged almost incessantly 

 and universally to breathe malarial emanations ; he is descended from 

 ancestors who, from prehistoric times, have lived in such poisoned 

 air ; he has thus become acclimatized to it more than any other race, 

 and on this account is able to prosper in places where the white man 

 would suffer for a long time (see Quatrefages's " Human Species," p. 

 223, Appletons' "International Scientific Series"). But we are not 

 told in what this acclimatization consists. Will the mosquito theory 

 furnish any probable explanation ? 



