8^ 
GARDENING AS A SCIENCE. 
hardy evergreen, is one of the most graceful in creation — the Eugenia myrtifolia. 
If this shrub be by accident injured, either by sudden or too much exposure to 
frost, its briUiant foliage and tender shoots are disfigured. Upon examination, it 
will then be seen that not a trace of bud can be discerned at the lower part 
of the stem, at which place it sometimes is needful to head it close down, so much 
as to leave only four or five inches of stem above the soil. If the plant, uninjured in 
its roots, be thus treated, and kept moderately watered in a cool greenhouse, fresh 
and numerous shoots will be protruded from the bark, and that in order beautifully 
symmetrical ; in a word, an entirely new and perfect plant is produced in one 
season. These buds must have pre-existed, remaining however dormant (yet 
sustained by the nutrimental matter of the medullary tissue) till they were called 
into motion by the vital principle. 
A leaf is a portion of this new system of life ; it is developed, and enlarges 
with its growth, and therefore partakes of the nature of the new succulent shoot ; 
we have therefore to consider the nature of the leaf, and to inquire into its 
component parts. 
Whether it be sessile^ that is, seated without footstalk close to the shoot, or 
petiolated — attached to its shoot by a stalk — it is connected with the vascular 
system by fibres and cellular tissue, which supply it with sap. These vessels 
pass in bundles, and ramify in various directions, constituting veins or nerves, 
the chief running along the centre, and becoming the midrib. But the substance 
of the leaves is in a great degree made up of cellular green tissue, deposited inter- 
mediately between the veins; we say green in a general sense, because most leaves 
are green, but to this, as in most other respects, the colour and arrangements of 
the cellular matter admit of numerous variations. " All," as Lindley remarks, 
" that appears uniform, with respect to this substance is, that it contains 
Chlorophyll in abundance, that it is traversed by air cavities in all directions, 
and that the latter are universally in communication with the domates" (stoma, 
Greek, a mouth,) or oscular pores — orifices which open a passage— pervious to the 
atmosphere, and by which it is reasonable to suppose the functions of respiration, 
of inspiring, transpiring, or both, are carried on. By the term Chlorophyll, is 
implied the yellowish- green tinting matter of the leaf ; it is of modern introduction, 
and is sufficiently expressive of the meaning intended to be conveyed. 
The pores are beautifully figured in Lindley's Elements of Botany under the 
head Elementary organs^ p. 7» No. 49, where they are described thus — " Stomates 
are oval spaces lying between the sides of the cells, opening into intercellular 
cavities in the subjacent tissue, and appearing to be bordered by a limb, (limhus, a 
border or edging,) when they are viewed from above." The three annexed 
drawings are calculated to convey some idea of the general position of the veins 
and supposed oscular pores ; they are not portraits, nor could such be attempted, 
because in every plate which we have seen, if compared with a microscopic 
investigation, some deviation or irregularity has been traced. 
