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removed three times during the summer ; and I also anticipate, that if 
two plots of turnips are grown under precisely the same circumstances, 
excepting that the leaves of one plot are mowed three times, and the 
plants of the other are allowed to retain their foliage entire throughout 
the growing season, that the latter, when weighed, will be found to yield 
a greater weight of roots per acre. If the positions are true, that ma¬ 
ture leaves, and of those such only as are not shaded by others are 
efficient; that young leaves are formed of matter previously prepared by 
mature leaves, and that the extent of the roots of a plant is commensurate 
with the extent of its foliage ; then the first effort of the turnip plant, 
when deprived of leaves, will be to make good the loss it has sustained, 
to restore the balance between roots and leaves ; to make good this loss, 
a quantity of organizable matter which had already been stored up in 
the roots, will have to be used in the formation of fresh leaves, and as 
immature leaves are less sufficient organs than mature leaves, the roots 
must sustain a farther loss—there must be a less amount of work done, 
according to the time required by the plant to mature efficient foliage. 
The effect of mowing the leaves of plants grown specially for the sake 
of their roots, may be yet better understood if we consider the most effi¬ 
cient mode of destroying deep-rooted perennial seeds. Some land which 
I broke up here was overrun with a quantity of the common fern, the 
root stock of this plant lies deeper than it is usual to plough, and the 
fern in consequence is a somewhat difficult weed to eradicate by the usual 
method of destroying weeds ; but if we consider the functions of leaves 
and how they are first formed or nourished, it must be apparent that 
there should be no difficulty in destroying the fern or any other deep 
rooted weed ; all that is required is to persist in not allowing the weeds 
to perfect their leaves, not to be satisfied with hoeing them down two or 
three times in early summer, but to persevere in cutting them off as long 
as they continue to be produced, never allowing them to reach maturity 
before they are destroyed. The issue may appear somewhat doubtful at 
first; but no plant, whatever may be the kind, or however favorably it 
may be situated, can withstand the constant loss of foliage. By this pro¬ 
cess the root is gradually exhausted of its organizable matter, the leaves 
produced become weaker and weaker, and finally the root perishes. 
The humid climate and murky atmosphere of England are favorable 
