On Malaria. 299 



is the error to which I here allude of misstating the cause and 

 nature of the summer fevers. 



It is this error chiefly, and further, that of looking for the 

 evidences of malaria in the production of intermittent solely, 

 which prevents a correct judgment from being formed of the 

 existence of this poison, and of the places producing it, though^ 

 in addition to the fevers of summer, I could, had 1 here sufficient 

 space, and were this a proper place for it, easily show that 

 a great many other disorders, often little suspected as conse- 

 quences of malaria, are equally produced by it, and are equally 

 the evidences of pernicious soils. But as I have no room for 

 detailing all this evidence, I must be content with saying, that 

 wherever I here mark any particular mode of land or water as 

 productive of malaria, it is, that in some one or more cases of 

 that variety, I have ascertained, by this very evidence, that it 

 was present, and the cause of disease ; while nearly all, perhaps 

 the whole, are further admitted or proved to be truly pernicious, 

 by the various French and Italian physicians, who have bestowed 

 on this subject an attention which has been utterly withdrawn 

 from it in England. And if this detail is general, rather than 

 special, it is not for want of special instances and proofs in 

 abundance, that I have not noticed these ; but from the recol- 

 lection, that to point out the insalubrity of certain spots, might 

 injure the properties, by affecting the value of those, should 

 that which is here adduced succeed in commanding belief. 



It is plain, to commence, that there is no mystery or charm 

 in the term, marsh ; and that if such a tract of land can pro- 

 duce disease, it is because it contains vegetables growing and 

 decomposing in a moist soil : this is the general analysis of the 

 cause ; and wherever, therefore, the same circumstances occur, 

 that spot must be, as to all the objects in view, a marsh, or a 

 source of malaria. A minuter analysis of the facts can scarcely 

 be necessary, either as to the plants that grow in marshes, or 

 to the mode in which the moisture exists : since, generally, the 

 plants are similar, while all vegetables appear indiscriminately 

 to produce the poison in question. 



In the next place, a marsh, in the popular sense of the term, 

 possesses a certain extent ; and in the popular view also, this 

 extent is judged necessary to the production of disease. .Facts, 



X 2 



