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 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 vigor 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 leaves are, therefore, branches.—The buds at bbbb have no leaves, and they remain the same
