GARDENING AS A SCIENCE. 
11 
the Collar^ may, perhaps, be viewed also as the point of separation — that, at which 
the ascending and descending vessels meet, and wherein the balance of power, of 
demand and supply, is duly regulated. In general, to cut a tree across at the collar 
is an act of destruction. Yet, as we have seen, the exceptions are numerous, since 
many roots abound with vital systems, which, being brought into action, develop 
suckers, that become trees or shrubs perfect in all their parts. 
2. The Stem of trees and slirubs is a continuation — an extension upwards of 
the root, commencing at the division called the collar. It is composed of the bark, 
and its covering integument, the wood, and the medulla or pith. According 
to Lindley, Elements^ No. 81, " The stem is produced by the successive develop- 
ment of leaf-buds, which lengthen in opposite directions." — " Leaf-buds consist of 
rudimentary leaves surrounding a growing vital point, the tissue of which is capable 
of elongation, upwards, in the form of a stem, and downwards, in the form of a 
root."— (No. 164.) 
Herbaceous or vegetable stems, annual or perennial, and which never harden into 
wood, proper, consist of bundles and masses of juicy cells and tubular vessels of 
various forms, with specific portions of central pith {medulla). 
On the subject of woody stems, as at present we are not speaking of tissue, it 
should be considered that they are evidently furnished with vital germs, numerous 
beyond the utmost stretch of imagination. We by no means are inclined to admit 
the idea of fresh creations ; that which ever can or will be developed in any tree 
we believe to exist rudimentally in the seed : for finite minuteness does not enter 
into the question. The power which can produce the entire system of a tree from 
one single eye or bud, can equally produce the Oak with all its numberless devel- 
opments of nine centuries, from the speck of life concealed within the acorn. Not, 
however, to indulge in abstruse speculations, it will be sufficient to observe that the 
branches, the spray or branchlets, the foliage, and finally the blossoms and fruit, 
are all of them the productions of buds ; each bud is therefore a system of life, 
complete in itself, and attached to the tree by organs or vessels by which it is 
supported and fed. The supporters are fibres, and these pass into the branchlets^ 
tending to confer substance, solidity, and springiness to each. If, then, a bud is 
complete in itself, and fully capable to produce the roots, trunk, and all the other 
parts of a perfect plant, and so on, as it were, ad infinitum, it follows that a tree 
raised from seed has derived all its members from that seed ; may we not therefore 
safely conclude that, the embryo of the seed comprised all and every portion of tlie 
tree that will be developed throughout countless generations ? 
We shall have to notice hereafter the organic structure of trees and herbs of 
all kinds : but it now remains in this preliminary article to endeavour, by a few 
general remarks, to harmonize the two sciences of physiology and chemistry ; or 
rather to prove that, so far as vegetable physiology is concerned, they are both one ; 
for it is utterly impossible to ascertain the constituents of plants and their products 
without appealing to the analytic powers of chemistry. 
