The scars on the stem are of three kinds, leaf, bud-scale, and flower-cluster scars. The pupils should notice that the buds are always just above the large triangular scars. If they are still in doubt as to the cause of these marks, show them some house-plant with well-developed buds in the axils of the leaves, and ask them to compare the position of these buds with their branches. The buds that spring from the inner angle of the leaf with the stem are _axillary_ buds; those that crown the stems are _terminal_. Since a bud is an undeveloped branch, terminal buds carry, on the axis which they crown, axillary buds give rise to side-shoots. The leaf-scars show the leaf-arrangement and the number of leaves each year. The leaves are opposite and each pair stands over the intervals of the pair below. The same is observed to be true of the scales and leaves of the bud.[1] All these points should be brought out by the actual observation of the specimens by the pupils, with only such hints from the teacher as may be needed to direct their attention aright. The dots on the leaf-scar are the ends of woody bundles (fibro-vascular bundles) which, in autumn, separated from the leaf. By counting these we can tell how many leaflets there were in the leaf, three, five, seven, nine, or occasionally six or eight. [Footnote 1: Bud-scales are modified leaves and their arrangement is therefore the same as the leaves. This is not mentioned in the study of the Horsechestnut bud, because it cannot be proved to the pupils, but the transition is explained in connection with Lilac, where it may be clearly seen. The scales of the bud of Horsechestnut are considered to be homologous with petioles, by analogy with other members of the same family. In the Sweet Buckeye a series can be made, exhibiting the gradual change from a scale to a compound leaf. See the Botanical Text-Book, Part I, Structural Botany. By Asa Gray. Ivison, Blakeman, Taylor and Co., New York, 1879. Plate 233, p. 116.] [Illustration: FIG. 13.--Horsechestnut. I. Branch in winter state: _a_, leaf-scars; _b_, bud-scars; _c_, flower-scars. 2. An expanding leaf-bud. 3. Same, more advanced.]