34 HABITUDES 



LECTUKE II. 



1 



THE CHARACTER, GROWTH, MINUTENESS, DIFFUSION, ALTERA- 

 TION BY CLIMATE, AND AUTUMNAL PROFUSION OF THE 







FUNGI. 



IN offering to your attention and consideration a theory 

 of malaria, I profess to do no more than present a review 

 of the phenomena which seem to render it probable, with- 

 out supposing, that, on so difficult and important a sub- 

 ject, I can produce, in your minds, the thorough convic- 

 tion, which, nothing short of a positive demonstration, 

 could bring home to my own. Not thoroughly convinced 

 myself, I can only be excused for occupying your time, 

 by the belief that the theory I am about to offer, is not 

 only very plausible, but is associated with agreeable and 

 useful collateral inquiries. If we should not discover at 

 the end of our journey, the truth, the search after which 

 has lured us to the path of observation, we shall enjoy, 

 at least, beautiful scenery by the way, and sometimes 

 pluck a flower, and sometimes find a gem. 



Standing, at St. George's, in Delaware, more than 



twenty years ago, upon the bottom of what had been, a 



short time before, a mill-dam, I found around me the un- 



/ decayed stumps of trees which had been, for one hundred 



-vj and seventeen years, submerged in fresh water. Two or 



