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ful than itself. But the well known fact is, that the disease will commit 
its greatest ravages in one field, while it entirely neglects, or but slightly 
visits another, in the immediate vicinity. Nay, it will entirely destroy 
one variety of potatoes in the same hill without in the least affecting 
another. 
The atmospheric theory is still more objectionable in some of its as¬ 
pects. It assumes that there is something in the atmosphere which 
specifically causes the disease ; some floating miasmata, or contagious 
influence, impregnating the currents of air, which are borne in fixed 
telluric directions ; in some instances, without material contact or pol¬ 
lution ; in others, acting as a most terrific vegetable plague. But 
however plausible this theory may be to those who have not examined 
the subject in reference to atmospheric influences, it is wholly irrecon¬ 
cilable with some of the known physical agents of the atmosphere. We 
cannot trace the morbific matter even from one field of potatoes to 
another much less across seas, mountains, and deserts, upon any 
known principle of atmospheric movement. Like the ravages of the 
cholera, the disease spreads from remote districts in the very face of the 
strongest winds. It refuses to be governed by any known laws, or 
reconciled to any known conditions in meteorological science. No trace 
of the morbific condition can be determined by analysis, or the keenest 
microscopic research. It escapes the application of every chemical test, 
and eludes every resort of human wisdom. 
It would certainly seem that, where the injury arises from sudden or 
extreme changes of weather, or from heavy rains, fogs, frosts, &c., the 
line or region of devastation ought to be more or less distinctly marked, 
if not strictly confined to the localities within which such meteorological 
changes, or causes, exist. The disease, to be induced by atmospheric 
influences, must manifest itself in the line of the existing or moving 
miasmata; or it would seem , at least, that it should so manifest itself. 
But the history of the disease shows that it does no such thing; that it 
is obedient to no such influences. It takes up its own line of march, and 
travels in obedience to its own hidden laws. It comes like some unpro- 
pitious destiny—some sudden stroke of fate—and smites down the best 
and most generous gift which nature ever dispensed with her liberal and 
benignant hand. It seizes upon its victim with the impetuosity of pas- 
