For filling cavities in heavy, swaying branches, one part of asphalt to four of clean, dry sawdust will form a mixture that is non-rigid and yields with the motion of the branch in which it is inserted. In dealing with the trunk, which is more rigid and less affected in stormy weather, a larger quantity of sawdust should be used. The filling is made by stirring dry sawdust into boiling asphalt until the desired consistency is reached, and before the composition has cooled, it should be inserted in the previously prepared cavity. As in cement filling, the preparation of cavities to be filled with sawdust and asphalt should be carefully attended to, the decayed wood and all soft and rotten material being removed, and the interior surface rendered sterile by an application of carbolineum or kerosene. For wound dressings, gas tar and liquid asphalt is to be recommended, this combination forming a more continuous and elastic covering than is the case when tar or paint alone is used. Where the cavity is small and, as is often the case, filled with water and decayed and decaying vegetable matter, the following course is recommended:—When only a few inches deep, the water can usually be got rid of by mopping it out with a sponge attached to a convenient handle, but when the hole is too deep for this method the water may be extracted by tapping, that is by boring a hole with an auger through the trunk to the bottom of the hole. A half-inch auger will suffice, and the correct spot to bore can usually be ascertained by measuring the depth of the hole. After the water has been removed the cavity must be thoroughly cleared of all decaying tissue and accumulated vegetable matter, and in order that this may be done effectually, it may sometimes be necessary to enlarge the opening so that a suitable tool can be inserted. When the cavity has become quite dry—a matter of considerable importance—it should be treated with creosote or carbolineum and afterwards filled with concrete in the proportion of one part of cement to four of clean gravel. Ram the concrete firm so that the cavity is perfectly filled, and finish off at the orifice with pure cement in such a way that the cambium may be induced to form a growth over the edge of the filling. A cheap but temporary method of dealing with small hollows and cavities in fruit and other trees, is to fill these with a mixture of clay and cow-dung in the proportion of two of the former to one of the latter. Knead well and apply when in the consistency of putty, cleaning and disinfecting the hollows before filling.