RECAPITULATION. 133 



plains, in our own southern country, emit a fungous or 

 mouldy odor,* soon after night; which fact has not a little 

 puzzled curious observers. 



May not the healthful power of the plough be mainly 

 attributed to its destruction of fungous growths of this, and 

 of other kinds. Almost every writer on malaria, speaks 

 of the beneficial influence upon health, of a constant culti- 

 vation. Now, we know, that when a country is covered 

 with woods, it is usually salubrious, and that when cleared, 

 and put under imperfect tillage, it becomes more sickly; 

 but that a regular system of husbandry by the plough, 

 restores to it all its former healthfulness ; while the placing 

 it for some time in pasturage, causes it to again retrograde 

 to a certain degree. The plough is the especial enemy of 

 the fungi, which, either beneath the surface, as truffles, or 

 upon it, as mushrooms, are obviously lessened or extirpated 

 by the constant disturbance of an active tillage. Nothing 

 else known to be capable of affecting the health of the in- 

 habitants, is materially altered by agricultural processes. 



I have now, gentlemen, brought to a close the pro- 

 longed examination of the cause of miasmatic fevers, and 

 non-contagious epidemics. Let me recapitulate, in a very 

 cursory way, the most important elements of our argu- 

 ment. 



I began, by showing that all the usually received opin- 

 ions on this subject, are liable t@ insuperable objections, 

 except that which refers to the causation by organic life, 

 and especially by animalcules, as held by Coluniella, 

 Kircher, Linnaeus, Mojon, and Henry Holland. 



* This is, probably, the cause of the musky odor noticed by Humboldt, 

 when the soil of sonae tropical regions is disturbed. 



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