104 The Potatoe Plague. 



been, very nearly the same, in all the countries where the 

 potatoe is grown, and, consequently, all the causes which pro- 

 duce the disease, have been simultaneously in operation, 

 everywhere. That the disease is not an epidemic, we know, 

 because sound and unsound potatoes are grown upon the 

 same field. I say that the causes of the disease lie where I 

 have placed them, because in almost every instance where 

 the treatment of the crop has been based upon this theory, 

 there has been no rot. There are, of course, exceptions to all 

 general rules, and exceptions may be named to this, but the 

 great fact remains true, and it will be a demonstrated truth 

 next year, by all who are careful in selecting land and pre- 

 paring their seed potatoes. 



Now I lay it down as an incontrovertible fact that potatoe 

 sets from a highly cultivated field, and from a large crop, are 

 not proper for seed, and that sets from such a crop will in- 

 evitably give a diseased product ; it may not be visible the 

 first year, or the second ; but the tuber is diseased, and the 

 disease will out. I do not say that farmers should not strive 

 for large crops, but merely that sets should not be taken 

 from them. I cannot 'precisely state the law governing this 

 fact, but it has been remarked by Professor Morren that the 

 potatoe is not a root only a branch ; and if the Professor 

 is correct, then an easy solution for it is at hand. The plant, 

 by over-production, has exhausted its vital energies. And 

 this would seem to be the true reason why sets from such a 

 crop are not proper for seed. 



OVER-RIPENING. Another cause to which I ascribe the 

 rot, is the planting of over-ripened sets. I believe it wiil not 

 be contended for a moment that over-ripened sets have not 

 generally been planted, neither will it be asserted that the 

 produce from sets not over-ripened have been, to any general 

 extent, affected by the disease. In some cases they have ; 

 but, then, it will be traceable to pre-existing disease, arising 



