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cholera could not be the cause of the epidemic, or excess of mortality, 

 because some were affected with other diseases. 



The English Commissioners doubted whether fungi were the cause of 

 the disease. The theory did not appear to them well established ; not 

 because botrytts infestans is a species of fungus which preys exclusively 

 on decaying matter, and not a parasite which produces decay ; but, said 

 they, "if fungi were the original cause of the disease, it is difficult to 

 conceive why fields of potatoes, placed very near each other, should be 

 differently affected, or why certain varieties of the plant should be much 

 less injured than others." But what reasoning is this ? Surely it did not 

 occur to them that this objection might be urged with equal force against 

 their own explanation of adverse weather. Might we not as reasonably 

 object that fungi could not be the cause of a patch of mildewed wheat 

 because the whole field was not attacked. And the fact that the varie- 

 ties which the Commissioners said had offered the greatest resistance to 

 the disease were previously known to possess greater constitutional vigor 

 than those which signally failed, was sufficient to account for the different 

 powers of the parasite over these varieties. 



The Commissioners were also "unable to reconcile with the theory of 

 the disease being caused by fungi, the remarkable fact that in its present 

 form it is certainly of modern origin. We must assume the botrytis to 

 have been co-existent with the potatoe itself, and therefore we must con- 

 clude that some recent causes must have come into operation favorable to 

 its increase to the present alarming degree." But why these "ifs and 

 doubts," upon a point which is capable of being decided by direct obser- 

 vation? If the fungus be a true parasite and not a species which preys 

 on decaying matter only, what does it matter whether we can understand 

 or not why different fields or varieties of potatoes should be differently 

 affected, or why the disease had not before been developed? If the 

 foundation be secure — if the main fact be placed beyond dispute, which 

 is the first thing to be considered, we may then be assured that all our 

 doubts admit of being satisfactorily explained, and our next endeavors 

 should be to find these explanations ; to discover, if possible, what are 

 the causes which have recently come into operation, favorable to the 

 increase of the parasite to the present alarming degree, and not to doubt 

 the habits and power of the parasite, simply because we cannot immedi- 

 ately find these explanations. 



As if, however, no longer to leave any room for doubt or cavil on this 



