THE GREENHOUSE. 
167 
mix a considerable portion of similar material, or small pieces of 
charcoal with the soil. This is certain to be beneficial in a me¬ 
chanical manner, by assisting the free percolation of air and 
water through the soil, even if it has not, as some affirm, a chemi¬ 
cal action on the roots. In potting, the small fibres should be 
gently disentangled, and carefully spread out near the surface of 
the new soil, and the collet of the plant, that portion from whence 
the roots issue, should always be kept just level with the top of 
the earth. Watering, at this season, should be conducted with 
much judgment and care. Some individuals that have begun a 
vigorous growth will require a liberal supply, while others still in 
a dormant state should have but little more than sufficient to pre¬ 
serve vitality, until they are induced by the season to begin, like 
their fellows, the development of their new parts. The inactive 
state which all plants fall into at some part of the year, but chiefly 
in winter, may be likened to the sleep of animals, and the watci 
which is poured into the soil about their roots as their natnral 
food. Therefore, to give water in any quantity to a plant in this 
state would be as injurious and unreasonable as to awake a tired 
and exhausted man to eat a full meal of heavy food. The quantity 
supplied should at all times be proportionate to the apparent 
state of the plant. It is true, by the continued application of 
stimulants, plants, like animals, may be kept in an active state 
beyond their natural periods; but, equally alike, each will ulti¬ 
mately suffer from the unnatural efforts their systems are thus 
forced to make. 
The food of plants is absorbed from the surrounding soil by 
the sponge-like extremities of their roots, and conveyed to the 
body of the plant. It is taken up in the form of water, but only 
certain portions, or constituents, of the moisture thus absorbed 
are available to the support and extension of the leaves and 
branches. The assimilated particles become converted, in the 
course of the season, by the action of atmospheiic influences ge¬ 
nerally, to the formation of new parts, and the increase of those 
already existing. This makes plain the necessity of preserving a 
pure atmosphere about the plants, with a duly regulated supply 
' of air and light. All vegetation progresses most rapidly beneath a 
moderately subdued light, new leaves and branches are then pio- 
duced in quick succession, as may be observed in the spring 
