umber
of systems is incalculable, and even to furnish any thing like a
representative number of types, I should have to give several hundreds
of figures such as Fig. 44.[251]

[Illustration: FIG. 41.]

[Illustration: FIG. 42.]

[Illustration: FIG. 43.]

[Illustration: FIG. 44.]

Thus far, however, we have only been speaking of the great relations of
stem and branches. The forms of the branches themselves are regulated by
still more subtle laws, for they occupy an intermediate position between
the form of the tree and of the leaf. The leaf has a flat ramification;
the tree a completely rounded one; the bough is neither rounded nor
flat, but has a structure exactly balanced between the two, in a
half-flattened, half-rounded flake, closely resembling in shape one of
the thick leaves of an artichoke or the flake of a fir cone; by
combination forming the solid mass of the tree, as the leaves compose
the artichoke head. I have before pointed out to you the general
resemblance of these branch flakes to an extended hand; but they may be
more accurately represented by the ribs of a boat. If you can imagine a
very broad-headed and flattened boat applied by its keel to the end of a
main branch,[252] as in Fig. 45., the lines which its ribs will take,
and the general contour of it, as seen in different directions, from
above and below; and from one side and another, will give you the
closest approximation to the perspectives and foreshortenings of a
well-grown branch-flake. Fig. 25. above, page 316., is an unharmed and
unrestrained shoot of healthy young oak; and if you compare it with Fig.
45., you will understand at once the action of the lines of leafage; the
boat only failing as a type in that its ribs are too nearly parallel to
each other at the sides, while the bough sends all its ramification well
forwards, rounding to the head, that it may accomplish its part in the
outer form of the whole tree, yet always securing the compliance with
the great universal law that the branches nearest the root bend most
back; and, of course, throwing _some_ always back as well as forwards;
the appearance of reversed action being much increased, and rendered
more striking and beautiful, by perspective. Figure 25. shows the
perspective of such a bough as it is seen from below; Fig. 46. gives
rudely the look it would have from above.

[Illustration: FIG. 45.]

[Illustration: FIG. 46.]

You may suppose, if you have not already discove