process of
assimilation, to aid in the extension of the plants.

This system of pruning, with reference both to the barren and the fruitful
branches, must be continued, whilst these continue in a vigorous and
healthy condition; but when any symptoms of decay or of expended powers,
are perceived, they should be pruned quite away, and young ones encouraged
in their stead. All the pruning which has been spoken of, except the
occasional removal of a main shoot, should be done at a sufficiently early
period of growth, to admit of being effected by means of the thumb-nail;
for like all other plants, Cucumbers are much best treated, when whatever
pruning they may require, is done at that stage of growth, when the least
amount of trouble and labour is required to perform it. Pruning is not
under any circumstances a natural process, and when we have recourse to it
in artificial cultivation, it is only an expedient, which is rendered
necessary by the limited space, within which it becomes necessary to
confine the extension of the plants; and since this is the case, it is far
better to remove a portion of any plant, at an early period of its
growth, and thus to economize its vital energies, rather than to suffer
them to be expended, and the supply to become exhausted through a
superfluous developement, and then to deprive it of those very organs, by
the action of which, the expenditure would be again recompensed to the
vital energies.

CHAP. V.

ON THE NATURE, AND COMPOSITION OF THE SOIL.

Plants absorb fluids through the extremities or spongioles of the roots,
and it is thus that those portions of the substances which serve them as
their food, and are derived from the soil, are carried into their system,
in a state of solution: these spongioles are not strictly to be regarded
as analogous to the mouths of animals, for they are not provided with
openings, and cannot imbibe even the most impalpable powders; their action
seems to be more analogous to that of the lacteals in animals, for these,
as well as spongioles, serve to convey fluids only. These considerations
render it necessary, that in the composition of soil for the growth of
plants, the following important points should be held in
consideration;--it should contain a sufficient ratio of organizable
matter, that is of substances which can be rendered available as food to
the plants; it should readily absorb fluids, since it is only when in a
state of solution, th