The question of identity of the alkaloid Harmin obtained from the stepped race with the plant base Banisterin isolated from a Liane Banisteria Caapi is in a perfect way by chemical means 1), due to precise crystal examinations 2) and by the harmonization of the pharmacological mode of action 3) has been decided. Nevertheless, it was very close to applying a very precise optical method, which is already frequently used today, namely the determination of the ultraviolet absorption spectrum, likewise to the two alkaloids. Both show an absorption maximum at about 320 micrometer in complete agreement.