Om Malaria. 315 



ments which returned to England from Walcheren in 1S09, appears 

 to me a satisfactory answer. Dr. Keate states that after their arrival 

 in England from that most disastrous campaign, where more lives 

 were lost by disease than by the collisions of war, " Many of the 

 men fell down suddenly after the fatigue of a short march with an 

 attack of the identical fever, so fatal at Walcheren," and he has no 

 doubt that the poison was imbibed there, and remained latent until 

 after their return. This seems to me so conclusive on this point, 

 that I need not take room to repeat other instances where the effect 

 of marsh effluvia had remained latent for different periods, from six 

 days to six weeks and more, and where the proximate cause of its 

 developement was fatigue, or a luxurious meal, night watching or 

 some other casual excitement. 



It has been further suggested, that it is a mistake to attribute this 

 class of maladies to a local cause, as the North American Indians 

 were not affected in the same manner, although more exposed to va- 

 rieties of soils and seasons than the present race of inhabitants. 

 That the Indians were subject to epidemics, we are informed by 

 Hutchinson, who in his " History of Massachusetts," remarks that 

 " the Indians had been greatly weakened by an epidemic." In Bel- 

 knap's Biography, " several periods of pestilence among the natives 

 of New England are named." It is mentioned, in " Gookin's His- 

 torical Collections of the Indians in New England," that consumption 

 and fever were among the diseases of the natives, and also, that they 

 invoked invisible spirits in powows, " to lay the latter distemper. ^^ 

 These siclmesses might, or might not be owing to causes at present 

 operating, but they could scarcely be as violent, because the swamps 

 and low grounds were screened in a good degree from the sun by 

 the almost impenetrable forests ; and the amount of humid vapors 

 would be proportionate to the degree of heat which exhaled them, al- 

 though their character might be influenced by other causes. 



The severe sickness, and the violent fevers, which assailed the ear- 

 ly settlers of this country, are famiharly known ; nor need we a re- 

 cord of the symptoms to convince us that they were analogous to 

 those which appear in every new settlement west of our Atlantic bor- 

 der, where the neivly cleared lands, are known to be sources of dis- 

 ease to the cultivators. When the deep accumulations of autumnal 

 leaves and other vegetable remains, which have been gathering for 

 ages, are broken up by the plough and exposed to the sun and 

 rain, those elements are necessarily disengaged and exhaled, whichj 



