SUGGESTIONS.—Some of the best of all observation lessons are those
made on dormant twigs. There are many things to be learned, the
eyes are trained, and the specimens are everywhere accessible.
=123.= At whatever time of year the pupil takes up the study of
branches, he should look for three things: the ages of the various
parts, the relative positions of the buds and the leaves, the
different sizes of similar or comparable buds. If it is late in
spring or early in summer, he should watch the development of the
buds in the axils, and he should determine whether the strength or
size of the bud is in any way related to the size and the vigour
of the subtending (or supporting) leaf. The sizes of buds should
also be noted on leafless twigs, and the sizes of the former leaves
may be inferred from the size of the leaf-scar below the bud. The
pupil should keep in mind the fact of the struggle for food and
light, and its effects on the developing buds. =124.= _The bud
and the branch._ A twig cut from an apple tree in early spring is
shown in Fig. 155. The most hasty observation shows that it has
various parts, or members. It seems to be divided at the point
_f_ into two parts. It is evident that the part from _f_ to _h_
grew last year, and that the part below _f_ grew two years ago.
The buds on the two parts are very unlike, and these differences
challenge investigation.—In order to understand this seemingly
lifeless twig, it will be necessary to see it as it looked late
last summer (and this condition is shown in Fig. 156). The part
from _f_ to _h_,—which has just completed its growth,—is seen to
have its leaves growing singly. In every axil (or angle which the
leaf makes when it joins the shoot) is a bud. The leaf starts
first, and as the season advances the bud forms in its axil. When
the leaves have fallen, at the approach of winter, the buds remain,
as seen in Fig. 155. Every bud on the last year’s growth of a
winter twig, therefore, marks the position occupied by a leaf when
the shoot was growing.—The part below _f_, in Fig. 156, shows a
wholly different arrangement. The leaves are two or more together
(_aaaa_), and there are buds without leaves (_bbbb_). A year ago
this part looked like the present shoot from _f_ to _h_,—that is,
the leaves were single, with a bud in the axil of each. It is now
seen that some of these bud-like parts are longer than others,
and that the longest ones are those which have leaves. It must be
because of the leaves that they have increased in length. The body
_c_ has lost its leaves through some accident, and its growth has
ceased. In other words, the parts at _aaaa_ are like the shoot
_fh_, except that they are shorter, and they are of the same age.
One grew from the end or terminal bud of the main branch, and the
others from the side or lateral buds. Parts or bodies that bear
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