The object of this investigation was the isolation of the alkaloids of Strychnos toxifera as this liane is the source of the renowned calabash-curare of British Guiana. By chromatography of the less soluble reineckates twelve crystalline quaternary salts, toxiferines-I to -XII have been obtained, two as the chlorides, and the remainder as picrates. Toxiferine-I chloride, an extremely potent curarising agent, was identical with the toxiferine-I chloride of Wieland, Bähr, and Witkop. Toxiferine-II picrate of these investigators was also encountered, the remaining ten toxiferines being apparently new. The curarising activity of some of these is comparable with that of toxiferine-I chloride. The neutral substance C21H25O3N 3 found by the above-named investigators in calabash-curare from Venezuela has now been found in St. toxifera. The striking colour reactions of these alkaloids suggests that they are all derived biogenetically from tryptophan.