1. Indian Hemp (Apocynum Cannabinum). The root is of a yellowish brown while young, but dark chestnut (red brown) when old, with a nauseous acrid taste. “The internal ligneous part is yellowish white.” “Powerfully emetic and cathartic, sometimes diuretic.”
2. Lobclina. “The active principle of lobelia is a yellowish liquid.” “Lobelia is emetic, occasionally cathartic, diaphoretic,” etc.
3. Tartar Emetic (KSbC4H4O7, H2O), “a white crystalline salt,” with the yellow, orange and red all strongly developed in the spectra of its elements. “According to the dose it acts variously as a diaphoretic, diuretic, expectorant, purgative and emetic.”
4. Bloodroot (sanguinaria). “The whole plant is pervaded by an orange-colored sap. The color of the powder is brownish red.” The leaf “is yellowish green on the upper surface, paler or glaucous on the under, and strongly marked by orange-colored veins.” “Sanguinaria is an acrid emetic, with stimulant and narcotic powers.”
5. The fact that emetics deal so much in the red as well as in the yellow principle shows that they act more or less upon the blood and muscular tissues as well as the nerves. “The action of an emetic is directly or indirectly upon the nerve centres that supply these muscles. * * All emetics acting through the blood produce more or less depression.” (Hartshorne). Emetics act principally upon the pneumogastric nerve.