DESCRIPTION OF DRUG.—Grows in swamps, and along the banks of streams and ponds. Subcylindrical sections of various lengths, about 20 mm. (⅘ in.) thick; externally reddish-brown, deeply wrinkled, marked below with rootlet scars (little elongated dot-like rings) in wavy, longitudinal lines, above with leaf-scars; fracture short, corky, showing a pinkish or whitish interior dotted with yellowish or brownish dots, both in the thick cortical layer and in the spongy central column; odor aromatic; taste peculiar, very bitter. Although the unpeeled rhizome is directed, the pinkish-white sections deprived of the corky layer are often met with in market.
STRUCTURE.—The tissue is chiefly parenchyma, traversed by yellowish fibrovascular bundles, most abundant just within and near the nucleus sheath. The cells of the parenchyma are filled with starch and volatile oil, the latter most abundant in the cortical layer. The spongy appearance of the central portion is due to large air-cells, as in all aquatic plants.
CONSTITUENTS.—Volatile oil 1 to 2 per cent., having the smell and taste of calamus, a bitter glucoside termed acorin (syrupy, yellow liquid), calamine, choline, resin, starch, and mucilage.
Isolation of Acorin.—A concentrated decoction of the drug is deprived of gum by precipitating with alcohol. The liquid is then treated with lead subacetate. The lead is removed by H2S. The resulting liquid, after neutralization, is shaken with chloroform, which leaves on evaporation a thin, yellow, aromatic liquid, acorin. This splits into oil and sugar by hydration; by oxidation the resin and acoretin are obtained.
ACTION AND USES.—Tonic and carminative, and a feeble aromatic stimulant. Dose: 15 to 60 gr. (1 to 4 Gm.).