CAPRICE OF MALARIA. 123 



One other difficulty remains to be removed, and I shall 

 then, gentlemen, leave this subject for your future con- 

 sideration, and, if worthy of it, your future investigation. 

 Writers on malaria not unfrequently complain of the un- 

 accountable irregularity of miasmatic action. Attributing, 

 as they usually do, the diseases of the autumn to vegetable 

 or other decomposition, they are disturbed by finding not 

 the slightest relation between the supposed cause and the 

 alleged effect. Heat, moisture, and vegetation being the 

 concurrent elements of their theory, some proportion 

 should be observed between the amount of these, and the 

 intensity or diffusiveness of malaria. But, alas for the 

 speculation, disease sometimes most abounds in seasons 

 remarkable for the negation of the alleged causes. Cool 

 years are healthy, cool years are sickly. Dry years are 

 salubrious, dry years are lethal.* Wet years present the 

 extremes of health and sickness, and years of a mixed 

 character have been in the plus and minus of the scale of 

 salubrity. Only one element seems to make any ap- 

 proach to a constant relation to the state of health, and 

 that is, a tendency to excess of vegetable life. In the 

 autumn of fertile years, there is often the greatest mor- 

 tality. 



Can this arise from the decomposition of the vegetation 

 of that year, which has just been completed? Does the 

 vegetation submit, in the open air, to so rapid a change as 

 that which is to be admitted, to rationally entertain the 

 malarious theory, as usually received ? I think not, and 

 farther, the occurrence of severe malarious diseases in 

 barren places, on rocky heights, and sandy plains, shows 

 that we may more rationally attribute the diseases of 



* "For atNewtown, Long Island, and in most parts of this island, these 

 diseases have existed in seasons of the greatest drought." (Hosack.) 



