The dried branches of Trichocereus terscheckii (Parmentier) Britton & Rose contain 0.25 to 1.2% alkaloids. From this source trichocereine, a new vegetable base, and the already known mezcaline have been isolated and characterized. The ratio of trichocereine to mezcaline is 5:l. The chemical structure of trichocereine has been shown to be N-dimethylmezcaline by degradation, and its synthesis has been achieved by allowing 3,4,5-trimethoxy-fi-phenylethyl chloride to react with dimethylamine. Hexalupine has been shown to be identical with d-thermopsine by means of their infrared spectra, and the melting points of several of their derivatives.