POTATO ROT. 659 



no other manure than a pint of unleached wood ashes in each 

 hill, in seasons when potatoes planted with ordinary manure 

 were blighted. 



For the same reasons it is, of course, unwise to raise succes- 

 sive crops of potatoes on the same soil. Whenever, on old land, 

 a proper rotation of crops is not attended to, there is much 

 greater likelihood of failure. 



7. Storing in dry cellars is of the first importance, when the 

 crop is infected. I have found that potatoes in which brown 

 spots of disease were already formed, had the progress of the 

 change arrested by being kept dry ; and that the diseased spots 

 dried up and lost their putrescent character. 



8. Where there is no hope of otherwise raising a crop, the 

 rotting potatoes may be grated or ground up, and the farina or 

 starch saved. With a little extra washing, it will be nearly as 

 good in quality, though usually less in quantity, than that from 

 sound potatoes. 



All the above, and probably other expedients, have been al- 

 ready approved by experience, as useful palliatives. In short, 

 anything that tends to place the plant in a natural and healthy 

 condition, appears to give it a much greater power of resisting 

 the cause of disease, whatever that may be. 



None of these secondary or partial remedies, however, can 

 be expected to eradicate the disease. They may temporarily 

 prevent it ; or, when present, mitigate its violence, or diminish 

 the loss resulting from it. But I shall presently show., that we 

 have no reason to suppose that any, or all of them, can effect a 

 perfect cure. 



We proceed then, in the next place, to inquire into the 



Primary or p-edisposing cause of the Disease and its remedies. 



Almost every fact that can be collected, seems to indicate 

 that there must be some general cause of this nature, which 

 began to operate only in modern times ; and which has, during 

 the last few years, been almost universally active, but modified 

 by the influence of the secondary causes above referred to. 



The ordinary popular resource in seeking for the origin of 

 the wide-spread epidemic, is to refer them to the atmosphere. 



