t 94 3 



called, are entirely free from the curl. But I r^ave a 

 very ftriking proof before my eyes at this moment, 

 that this is not the cafe. A large field, which was 

 planted with potatoes the third year from the feed, 

 has more than one half the plants curled; while 

 another field near it, raifed from potatoes that never 

 were, that we know of, produced from feeds in this 

 country, has fcarcely one curled plant in the whole. 



It is by fome alledged, that the foil or feafon 

 occafion the difeafe: but that this is not the cafe, 

 is alfo plain from the ftate of a field now in my 

 neighbourhood. Several ridges in it, that were 

 planted with potatoes obtained from one particular 

 perfon, are very much curled, while the remainder 

 of t}ie field, which was planted with potatoes of the 

 fame fort, obtained from a different perfon, is not 

 at all infefted with that difeafe. In this cafe the. 

 foil and climate were the fame, (for the ridges were 

 intermixed with the others) but the crop extremely 

 different. 



In the lafl example it is plain, that the difeafe de- 

 pends entirely on the nature of the feed -, and it 

 feems to me highly probable that the curl in po- 

 tatoes, like fome hereditary difeafes among animals, 

 if once introduced, vitiates the prolific ftamina, fo 

 as to be perpetuated as long as the infe&ed breed 



continues 



