In cutting or foreshortening small branches, a sharp pocket-knife will be found most convenient, but when large limbs have to be removed the pruning saw should be brought into request. The branch to be removed, especially if of large size and weighty, should first be cut through at any convenient distance from the main stem, thus preventing splitting and tearing of the bark, after which the stump may be neatly sawn through as close to the bole of the tree as possible. Undercutting by a few draughts of the saw will here also go far in preventing tearing of the wood and bark. So as to render the saw-cut smooth and prevent water lodging on the surface, the face and edge should be neatly dressed with an adze or sharp pruning knife, and then painted with tar. When cutting over an upright-growing branch, such as in pollarding trees, etc., never cut on the horizontal, but always in a sloping direction, so that the rain may pass off quickly. CHAPTER XVI BRACING AND REPAIRING TREES Though occasionally resorted to in olden times, particularly in the case of orchard trees, it is only of late years that the systematic treatment of tree wounds and diseases has been generally adopted. Even at the present time, the filling of hollow trunks, bracing of heavy and diseased branches and attention to insect and fungoid pests are rarely engaged in and but imperfectly understood. When the value of old trees in an ornamental or utilitarian sense is taken into account, it is remarkable what a small amount of attention they receive when subjected to accident or disease. As a general rule, cavities or hollows in a tree stem, if left to themselves, gradually increase in size until the ascending sap is entirely cut off, when the crumbling stem either falls to pieces or is broken over by the wind. A branch requires to be braced or strengthened when from its weight and shape it is likely to get wrenched from the main stem during stormy weather and so injure the tree or man its natural beauty. Both insect and fungoid pests do a considerable amount of damage to trees, both young and old, but as special chapters are devoted to their depredations they need only receive a passing notice here. =Hollow Trunks and their Treatment.=—However desirable it may be to repair hollow trunks, yet a great deal of discrimination is necessary in deciding which trees should be operated upon, especially in the case of such as are reduced to mere shells and are not likely to derive any benefit commensurate with the labour and cost of materials involved in bracing and filling.