In young trees set for the purpose of top-working, the trunk may be cut off at the desired height and two cions inserted. The entire top is then removed at once; this is allowable only on young trees. Probably the better practice is to graft the main small side limbs and the main trunk or leader higher up. Usually it is better to leave some of the branches on the tree, not removing them all till the second or third year. In old apple-trees, the main branches are grafted, where they are an inch or two in diameter. Care is taken so to choose the branches that a well-shaped free-headed tree will result. Only a small part of the top is removed the first year, and three or four years may be required to change the top all over, the old branches being removed as the new ones grow. In about three years, or four, the grafts should begin to bear,--about as soon as strong three-year-old trees planted in the orchard. Any variety of the pomological apples will grow on any other variety, but apples do not take well on other species, as does the pear. The pear may be made to grow on the apple, but the graft is short-lived and the practice is not recommended. Boys may graft indiscriminately for practice, but grown-ups, having arrived at the unfortunate age of discretion, must operate only on those kinds known to succeed when joined. I have never known a boy who did not want to graft anything, as soon as his attention was called to the operation. The boy does not take it for granted: he wants to try. XIII THE MENDING OF THE APPLE-TREE Many accidents overtake the apple-tree. The hired man skins the tree with the harrow; fire runs through the dry grass; hard winters shatter the vitality, and parts of the tree die; borers enter; rabbits and mice gnaw the bark in winter; loads of fruit and burdens of ice crush the tree; wind storms play mischief; bad pruning leaves long stubs, and rot develops; cankers produce dead ragged wounds; fire-blight destroys the tissue; a poorly formed tree with bad crotches splits easily; grafts fail to take, and long dead ends are left; the tree is injured by pickers; vandals wreak their havoc. All these accidents must be met and the damages repaired. The surgeon must be summoned.