The rhizome and rootlets of Hydrastis canadensis.

Characters. - Rhizome about 1 1/2 inch long and 1/4 inch thick; oblique, with short branches, somewhat annulate and longitudinally wrinkled; externally yellowish-grey; fracture short, waxy, bright reddish-yellow, with a thickish bark, about ten narrow wood-wedges, broad medullary rays and large pith. Rootlets thin, brittle, with a thick, yellow bark, and subquadran-gular, woody centre. Odour slight; taste bitter.

Composition. - It contains the yellow, bitter alkaloid ber-berine (p. 838), and the colourless, also bitter, hydrastia, or hydrastine, besides a third alkaloid and a volatile principle not yet isolated.

U.S.P. Preparations.

dose.

Extractum Hydrastis Fluidum........................................................................

1-2 fl. dr.

Tinctura Hydrastis..........................................................................................

2-5 fl. dr.

Uses. - Its uses are similar to those of the simple bitters (p. 364). Professor Rutherford found the resinous substance obtained from the root to be an hepatic stimulant of moderate power (p. 403). This substance, which is also called hydrastin, must not be confounded with the alkaloid. It consists of a mixture of hydrastine, berberine, and resin in varying proportions. The pure alkaloid hydrastine is said to be antiperiodic, and causes ringing in the ears like quinine. The mixture of the alkaloids acts as an emmenagogue (vide p. 453).