=Cleft-grafting= _is practised in spring, as growth begins. The scions are cut previously, when perfectly dormant, and from the tree which it is desired to propagate_. The scions are kept in sand or moss in the cellar. Limbs of various sizes may be cleft-grafted,—from a half inch up to four inches in diameter; but a diameter of one to one and a half inches is the most convenient size. All the leading or main branches of a tree top may be grafted. If the remaining parts of the top are gradually cut away and the scions grow well, the entire top will be changed over to the new variety. [Illustration: FIG. 165.—SCION OF APPLE.] [Illustration: FIG. 166.—THE SCION INSERTED.] [Illustration: FIG. 167.—THE PARTS WAXED.] Another form of grafting is known as =budding=. In this case a single bud is used, and it is slipped underneath the bark of the stock and securely tied (not waxed) with soft material, as bass bark, corn shuck, yarn, or raffia (the last a commercial palm fibre). Budding is performed _when the bark of the stock will slip or peel_ (so that the bud can be inserted), and _when the bud is mature enough to grow_. Usually budding is performed in late summer or early fall, when the winter buds are well formed; or it may be practised in spring with buds cut in winter. In ordinary summer budding (which is the usual mode) the “bud” or scion forms a union with the stock, and then lies dormant till the following spring, as if it were still on its own twig. Budding is mostly restricted to young trees in the nursery. In the spring following the budding, the stock is cut off just above the bud, so that only the shoot from the bud grows to make the future tree. This prevailing form of budding (shield-budding) is shown in Fig. 168.