COMMENTARY. It is the _Potamogiton natans_, L. Dioscorides says of it, that it is cooling and astringent, and is applicable in cases of pruritus, and in spreading and inveterate ulcers. (iv, 99.) In some of the editions of his works, another species is described and recommended in dysentery, colic, and the red fluor of females. It cannot be so decidedly determined. Galen and the other authorities treat of it in general terms, like our author. Such of the Arabians as treat of it borrow from Dioscorides. See Avicenna (ii, 2, 352.) Ποτέρριον, Poterrhium, (called by some Phrœnium); its roots when cut into slices agglutinate divided tendons and wounds; and the decoction of it when drunk relieves affections of the nerves. * * * * * COMMENTARY. Matthiolus confesses his ignorance of it. Sprengel is inclined to think that it is the _Astragalus Poterium_, Pall. But Dr. Lindley holds it to be _Astragalus Creticus_. (Veg. King. 548.) Dioscorides says it has stalks like those of tragacanth, and accordingly Linnæus holds this plant to be a species of tragacanth. He recommends it in exactly the same cases as our author. Galen describes it by the name of _Neuras_. We have not been able to detect it in the works of the Arabians. Πράσιον, Marrabium, _Horehound_, is calefacient in the second degree; but more desiccative. It removes obstructions about the liver and spleen, and those of the chest and lungs. It also promotes menstruation. In a cataplasm it is detergent and discutient, and otherwise it is detergent and incisive. * * * * *