f counterbalancing either defective or
unsuitable management. The application of these agents to the cultivation
of the plant under consideration, in the winter season, will form the
subjects of succeeding chapters. I will here briefly direct attention to
the importance of light in the growth of plants, and then devote some
space to the consideration of the subject of pruning and training.

Light is most essential to the perfect and healthy developement of
vegetable organization, the performance of the functions essential to the
health of plants being dependent on its agency. It cannot indeed be
assumed that plants will not continue to grow, unless they are supplied
with an intense degree of light; but it is certain that the successful
nature of their growth, their maturation, and their fructification, are
dependent in no ordinary degree upon the nature and force of its action;
for without it, the vital energies of animated beings are unable to
maintain and perform the processes of elaboration, and assimilation, upon
which their nutrition depends. The mere extension of vegetable tissue, may
indeed go on, though less satisfactorily, under the almost total privation
of light, but with the exception of cryptogamic vegetation, the organs of
fructification are not under those circumstances, produced at all: the
stem may be formed, but does not become solid: the leaves may expand, but
their condition is imperfect; and it is only by means of the full and
complete action of these organs in the nutrition of plants, that the
developement of the floral parts is brought about: the roots may take up
fluids, and these may be conveyed in the natural upward channels, and then
dispersed among the stems and the leaves; but it is the action of solar
light, aided indeed by the natural condition of the elements supplying
heat and moisture, which alone, by a process of elaboration, can convert
this fluid, once crude and undigested, into the compound organic
substances, such as lignin, gum, starch, gluten, &c. which in their turn,
are destined to minister to the support of the organs of reproduction.
Growth, that is mere extension, may go on in proportion as heat and
moisture are supplied to plants, but light is the agent to whose especial
influence we owe the production of their active properties and secretions,
and the perfection of their fruit.

If then light is so indispensable to the vegetable frame, how important it
is that the structur