324 
doubtless improved by a proper selection of soils, 
and by employing peasants from the vine countries 
of France in cultivating the grape, and in the ma- 
nufacture of wine. The flavour of the juice of 
the grape changes as the soil is different, and in 
selecting a place for a vineyard, much may be 
gained by analyses or chemical examination of the 
soil, and by comparing it with the best soils of the 
best wine provinces of France, Germany, and 
Spain. This is a subject not unworthy the atten- 
tion of our government. 
Though the general composition of plants is 
very analogous, yet the specific difference in the 
products of many of them, and the facts stated in 
the last Lecture, prove that they must derive dif- 
ferent materials from the soil ; and though the 
vegetables having the smallest systems of leaves 
will proportionably most exhaust the soil of common 
nutritive matter, yet particular vegetables, when 
their produce is carried off, will require peculiar 
principles to be supplied to the land in which they 
grow. Strawberries and potatoes at first produce 
luxuriantly in virgin mould recently turned up 
from pasture ; but in a few years they degenerate, 
and require a fresh soil ; and the organization of 
these plants is such, as to be constantly producing 
the migration of their layers : thus the strawberry 
by its long shoots is constantly endeavouring to 
occupy a new soil ; and the fibrous radicles of the 
potatoe produce bulbs at a considerable distance 
from the parent plant. Lands in a course of years 
often cease to afford good cultivated .grasses ; they 
become (as it is popularly said) tired of them ; and 
