The acorn of the beech, when given to swine,[2249] makes them brisk and lively, and renders the flesh tender for cooking, and light and easy of digestion; while, on the other hand, that of the holm oak has the effect of making them thin, pallid, meagre, and lumpish. The acorn of the quercus is of a broad shape, and is the heaviest as well as the sweetest of them all. According to Nigidius, the acorn of the cerrus occupies the next rank to this, and, indeed, there is no acorn that renders the flesh of swine more firm, though at the same time it is apt to impart a certain degree of hardness. The same author assures us also, that the acorn of the holm oak is a trying diet for swine, unless it is given in very small quantities at a time. He says, too, that this acorn is the last to fall, and that the flesh of swine, if fed upon the acorns of the æsculus, the robur, or the cork-tree, will be of a spongy nature. CHAP. 9.—THE GALL-NUT. All[2250] the glandiferous trees produce the gall-nut as well: they only bear acorns, however, in alternate years. The gall-nut of the hemeris[2251] is considered the choicest of all, and the best adapted for the preparation of leather: that of the latifolia closely resembles it, but is somewhat lighter, and not by any means so highly approved. This last tree produces the black gall-nut also—for there are two varieties of it—this last being deemed preferable for dyeing wool. (7.) The gall-nut begins to grow just as the sun is leaving the sign of Gemini,[2252] and always bursts forth in its entirety in a single night.[2253] The white variety grows, too, in a single day, but if the heat happens to overtake it, it shrinks immediately, and never arrives at its proper size, which is about that of a bean. The black gall-nut will remain green for a longer period, and sometimes attains the size of an apple[2254] even. The best kind is that which comes from Commagene,[2255] and the most inferior are those produced by the robur: it may easily be tested by means of certain holes in it which admit of the passage of the light.[2256] CHAP. 10.—OTHER PRODUCTIONS ON THESE TREES BESIDES THE ACORN.