The Potatoe Plague. 75 



they improved very much ; and this is quite in keeping with 

 my theory, as when once the plant has a stem and leaves 

 whereby to elaborate nourishment from the atmosphere, and 

 roots which purvey from below, a large supply of moisture 

 will give it such an abundant flow of sap that the" vitiated 

 juices of the decaying set will both be very much diluted and 

 the plant will derive sufficient vigor from external sources 

 to outgrow a slight ailment ; whereas in a droughty season, 

 the plant is much more dependent on the set, and this at such 

 a time furnishes the poison in a concentrated form. 



The next objection I shall notice is, that one of the best 

 ways of getting rid of curl hitherto known, is to grow the 

 potatoes intended for seed on a piece of old meadow or other 

 land that has been long uncropped. This is easy of expla- 

 nation. Fresh land contains a supply of food which hag 

 been accumulating for years, and accordingly produces a 

 more luxuriant growth and later maturity. Every one must 

 have remarked that in a dry season plants of all kinds are 

 less fully developed, but ripen earlier. This is doubtless 

 owing to the less liberal supply of nourishment which they 

 receive; for even where the land is abundantly manured, 

 plants cannot avail themselves of it without moisture. When 

 a plant has attained a certain stage of growth, even though 

 considerably below its ordinary developement, should its sup- 

 ply of food be stinted, either in consequence of drought, or of 

 a scarcity of the necessary elements in the soil, it will at once 

 proceed to form and mature its seed. This is readily observ- 

 able in the case of weeds. The same species of grass which 

 is common in our meadows will be frequently found grow- 

 ing by a roadside, or even on a gravel walk, and in dry 

 weather will flower and bear seed, though so stunted and 

 dwarfish as scarcely to be recognizable. This will occur con- 

 siderably earlier in the season than the time of ripening of 

 the same species of grass in an ordinary meadow, and again 



