COMMENTARY. It has been usually taken for the _Convallaria Polygonatum_, which has obtained the same character as a medicine in modern works on the Mat. Med. See Rutty (M. M. 403) and Gray (Suppl. to the Pharmacop. 23.) Our author copies almost word for word from Galen, who, in his turn, borrows from Dioscorides. None of the Arabians have noticed it, as far as we can discover, except Ebn Baithar, who merely gives the descriptions of it by Dioscorides and Galen. It is not to be found in the works either of Hippocrates or Celsus. Πολύγονον, Polygonon, _Knot-grass_, has some astringency, but a cold watery principle of the second order is what prevails in it. When applied cold externally, it therefore relieves ardor of the stomach, erysipelas, and hot inflammations. Being of such a nature it repels defluxions, and thereby appears to be desiccative. The male is stronger than the female. * * * * * COMMENTARY. Of the two species described by Dioscorides, the mas is undoubtedly the _Polygonum aviculare_, and the feminine probably the _P. maritimum_. How the latter could be the _Hippuris vulgaris_, as several of the older commentators on Dioscorides had supposed, we are at a loss to comprehend. Two plants so dissimilar as the knot-grass and the mare’s-tail, could never have been classed by the ancients as male and female. Dioscorides gives a most interesting exposition of the medicinal powers of the former species, but as our author borrows from him, we need not dwell upon the other. It is possessed of an astringent and refrigerant power, and its juice (decoction) is suited to cases of hæmoptysis, fluxes of the belly, chorea, strangury, and so forth. (iv, 4, 5.) Galen taxes Dioscorides with not stating precisely what the particular cases of strangury are in which it is applicable. Otherwise his characters of this article agree exactly with those of Dioscorides and our author. Celsus ranks “herba sanguinalis, quam Græci πολύγονον vocant,” among things which are at the same time gently repressing (astringent?) and emollient. (ii, 33.) The Arabians who treat of the polygonum follow Dioscorides. See in particular, Avicenna (ii, 2, 725) and Ebn Baithar (ii, 195.) Our quaint old herbalist Culpeper, under the head of knot-grass, assigns to it exactly the same medicinal virtues as Dioscorides does to the Polygonum Mas and although the _Polygonum aviculare_ was ejected from our Dispensatory more than a hundred years ago, it is still to be found in the shops of our apothecaries, where it has the reputation of being “a vulnerary and astringent herb.” Gray (Suppl. to the Pharmacop. 42.) Πολύκνημον, Polycnemon, is heating and desiccative in the second degree, so as to agglutinate wounds. * * * * *