We have already[256] spoken of the different kinds of gum; the better sort of each kind will be found the most effective. Gum is bad for the teeth; it tends to make the blood coagulate, and is consequently good for discharges[257] of blood from the mouth. It is useful for burns,[258] but is bad for diseases of the trachea. It exercises a diuretic effect, and tends to neutralize all acridities, being astringent in other respects. The gum of the bitter-almond tree, which has the most[259] astringent properties of them all, is calorific also in its effects. Still, however, the gum of the plum, cherry, and vine is greatly preferred: all which kinds, applied topically, are productive of astringent and desiccative effects, and, used with vinegar, heal lichens upon infants. Taken in must, in doses of four oboli, they are good for inveterate coughs. It is generally thought that gum, taken in raisin wine, improves the complexion,[260] sharpens the appetite, and is good for calculi[261] in the bladder. It is particularly useful too for wounds and affections of the eyes. CHAP. 65. (12.)—THE EGYPTIAN OR ARABIAN THORN: FOUR REMEDIES. When speaking[262] of the perfumes, we have descanted upon the merits of the Egyptian or Arabian thorn. This, too, is of an astringent nature, and acts as a desiccative upon fluxes of all kinds, discharges of blood from the mouth, and excessive menstruation; for all which purposes the root is still more efficacious. CHAP. 66.—THE WHITE THORN: TWO REMEDIES. THE ACANTHION; ONE REMEDY. The seed of the white thorn is useful as a remedy for the stings of scorpions, and a chaplet made of it, is good for headache. Similar to this plant is that known to the Greeks as the “acanthion;”[263] though it is much smaller in the leaf, which is pointed at the extremity, and covered with a down like a cobweb in appearance. This downy substance is gathered in the East, and certain textures are made of it similar to those of silk. An infusion of the leaves or root of this plant is taken for the cure of opisthotony. CHAP. 67.—GUM ACACIA: EIGHTEEN REMEDIES.