Conversion to the isomeric lactone affords an excellent means for detecting dihydroabietic acid in the presence of large proportions of other resin acids. By this means dihydroabietic acid has been shown to be present in the oleoresin and the rosin of P. palustris and P. caribaea. Cold concentrated sulfuric acid has been shown to isomerize l-pimaric acid into l-abietic acid. Lactonized dihydroabietic acid may readily be prepared from commercial hydrogenated rosin. A new alkaloid, named erythramine, has been isolated from the seeds of Erythrina sandwicensis Deg. and Erythrina subumbrans (Hassk.) Merrill. Hypaphorine was isolated anew from Erythrina sandwicensis and was re-isolated from Erythrina subumbrans. The crystalline erythramine base, hydriodide, hydrobromide, and the hydrochloride have been described. The microanalyses showed that erythramine has the empirical composition, C18H21NO3. Erythramine was strongly active in causing a curare-like paralysis in frogs. Hypaphorine was converted to methyl a-dimethylamino-β-(3-indole)-propionate methiodide and this derivative was found to cause a curare-like paralysis in frogs when a high dose was administered.