OF THE MARSH POISON. 291 



ehievous effects. The most ignorant peasant of Lincolnshire 

 knows, that there is nothing to be apprehended from the 

 ditches of his farm till they have been dried up by the summer 

 heat ; and though the inhabitant of Holland may point to the 

 unexhausted foul canal as the source of his autumnal fever, 

 there can be little doubt that he might live upon a sea of the 

 same with impunity, and that it is to the absorbed waters un- 

 der his feet, which, without the canal, would in all probability 

 be much more pestilential, he ought to attribute his disease. 

 To assert, after all this, that the putrid marsh, which must ne- 

 cessarily, to a certain degree, be a wet one, is positively less 

 dangerous than another where no smell exists, will not, I am 

 sure, appear paradoxical to the Society ; for it is only saying, 

 that the first has not yet arrived at the degree of exsiccation 

 that has been found most productive of the marsh poison, and 

 that putrefaction, though it may, and must often precede and 

 accompany pestilence, is no part of pestilence itself. 



The symbol of vegetable putrefaction, in the decay of the 

 aquatic weeds that cover the pool, constantly meets the eye, 

 and deceives the judgment ; and the smell of the putrefying 

 waters combined with it, confirms a delusion which has ever 

 prevented us from discovering, that the action of a powerful 

 sun on its half-dried margin, is adequate to the production of 

 all that could be attributed to the humid decay of vegetables. 

 The greatest danger then may, and does often exist, where no 

 warning whatever is perceptible to the senses, and whoever, 

 in malarious countries, waits for the evidence of putrefaction, 

 will, in all the most dangerous places, wait too long, as every 

 one can testify who has seen pestilence steam forth, to the pa- 

 ralyzation of armies, from the bare barren sands of the Alen- 

 tejo in Portugal, — the arid burnt plains of Estremadura in 

 Spain, — and the recently flooded table-lands of Barbadoes, which 



have 



