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 has 
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 itsseed. 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 
