forester usually gets over these difficulties by planting beech, or silver fir, or some other species among the oaks, but in such a way that the oaks are never completely shaded by the other trees—that is to say, he keeps the trees at different ages, the beach, hornbeam, silver fir, spruce, etc., only being allowed to just close in the forest, leaving the leaf-crowns of the oaks to be fully exposed to the light above. The oak grows faster than the beech or spruce, for instance, while young, and so keeps its head easily above the others for a time. Very often the oak is cultivated pure at first, and then, when the oaks are becoming too crowded and he has to thin them, the forester puts in the silver fir or beech, which prevents the light coming in to the lower parts of the young oak-trees, and consequently prevents the development of lower branches, which would give the spreading, squat habit he wishes to prevent. For without light the leaves of the lower twigs of course can not make the materials to strengthen and thicken the latter into branches, and so they die off, and the trunk remains a straight, clean cylinder.
Although oaks are often raised from seed, a number of veteran trees being allowed to stand for many years in order to scatter the acorns, yet in by far the greater number of cases the plants are put in artificially, the long tap-roots being first cut in order to make them throw out lateral rootlets. It is also a common practice to cut back oaks, and allow them to sprout into what is known as coppice—that is to say, numerous buds which