_A collyrium which I use for removing the callosities of fistulæ._ Mix with vinegar equal parts of ammoniac perfume, of copperas, of verdigris, of misy, of chalcitis, and of gum.—_Another_, from the surgical works of Heliodorus: Of calamine, of misy, of copperas, of burnt copper, of gum, of each, dr. iv; of crude chalcitis, dr. iij; mix with the urine of a young person not come to manhood, and form collyria. Put this collyrium into the fistula, and apply externally the inner part of bread soaked in water, changing it until the inflammation subside, and the eschar fall off.—_Another_, which I received in Alexandria: Of the roots of alkanet, of toasted misy, of chalcitis, of verdigris, of fissile alum, of copperas, of aloes, of each, oz. j; triturate along with fine cantharides in vinegar, and make collyria.—_Another_: Of copperas, dr. ij; of chalcitis, of verdigris, of each, dr. j; mix with ammoniac and use, and when the callus is thrown off, cleanse with verdigris and eight times the quantity of the purest honied water; but after the discharge of the callus, incarnants must be used. An incarnative collyrium: of aloes, of myrrh, of ammoniac, of the cinders of egg shells, equal parts; having triturated with water form collyria, and apply.—_Another_: Of myrrh, of aloes, of frankincense, of pomegranate rind, equal parts, mix with water; but some use bull’s gall. The oil of unripe olives is incarnative when injected. I knew a person who injected cedar-rosin into fistulæ, and succeeded surprisingly. After it is incarnated we must have recourse to the agglutinative medicine, according to the plan described for other sinuses. “When the fistula is narrow and long,” says Galen, “and does not appear to me to contain callus internally, but only sordes, I first inject lye into it, and then allowing it to remain in the fistula until I expect that the sordes has fallen completely off, I afterwards apply the medicine.” It was the one from the oil of palma Christi, mentioned above. * * * * * COMMENTARY. We shall have occasion to refer to the Hippocratic treatise ‘De Fistulis,’ in the Sixth Book.