The Potatoe Plague. 63 
burn the leaves, for a field may appear secure from the 
botrydis, when it is not so; several leaves are attacked; 
these leaves throw the propagule on to the tubercles, which, 
if preserved for the purposes of reproduction, will spread the 
plague the following year. 
If the potatoes themselves are attacked, it is essential to 
separate as speedily as may he, the potatoes that are tainted 
from those that are not. Turn the sound ones over to account 
as soon as possible, for they are not noxious so long as the 
rind does not become yellow. The diseased ones should be 
burnt. 
As itis probable that the tubercles preserved for seed will 
be infected with the spawn of the mushroom, it would be ad- 
visable for cultivators who can, to procure tubercles for 
reproduction from places where the present scourge is 
unknown. ~ 
In case of using for reproduction the tubercles of crops 
visited by the plague this year, it will be necessary to sub- 
mit them, previous to planting, to the agency of lime, as it is 
practised with wheat and all plants that are liable to invasion 
by parasitical bodies. The process ought to be by the zm- 
mersion of the tubercles in lime water. Fifty pounds of 
lime, a quarter of a pound of sulphate of copper, and six 
pounds of marine salt, for twenty-five quarts of water, consti- 
tute a preparation, the utility of which, in the destruction of 
parasite vegetation, has been experienced by a great number 
of well-informed cultivators. 
In the plantations of the spring of 1846, it is essential to 
plant potatoes in fields as far as possible removed from those 
actually infected this year, to avoid the danger from the 
retention in the soil of the spawn of the fungus. 
The use of lime and manure salt, with a slight mixture of 
sulphate of copper, is, as I have already said, of acknowl- 
edged efficacy in the destruction of parasite germs. Conse- 
