The faster rate of reaction with mercuric acetate of speciogynine compared with mitraciliatine, confirms the assignment of the normal configuration to speciogynine. The assigned configurations of speciociliatine (epiallo), mitraciliatine (pseudo) and hirsutine (pseudo) are confirmed by formation of these alkaloids from mitragynine (allo), speciogynine (normal) and dihydrocorynantheine (normal), respectively, by mercuric acetate oxidation followed by zinc/acetic acid reduction. © 1968.