1. The first person to draw the attention of the scientific world to peyote was doubtless Dr. J. R. Briggs, and not Mrs. A. B. Nickels as is often stated. 2. The first report of alkaloids in peyote seems to be the laboratory report by F. A. Thompson at Parke-Davis, although Louis Lewin was the first to publish. 3. The variability of Lophophora williamsii and imperfect knowledge of the species laid the foundation for the controversy over botanical names. Only recently have field studies in Mexico indicated that there are two species, Lophophora williamsii and L. diffusa, differing in distribution and chemical characters. Anhalonium lewinii is now referred to L. williamsii. 4. Present and earlier studies of the Quer6taro peyote, Lophophora diffusa, show that this species differs considerably in its alkaloid set-up from L. williamsii. L. diffusa produces predominantly (> 90%) phenolic tetrahydroisoquinoline alkaloids (mainly pellotine) and almost no mescaline. This lends support to the earlier postulation of an independent metabolic pathway to pellotine and anhalidine. 5. In our opinion, Heffter's results with Anhalonium williamsii can be explained if we assume that his plant material was collected in Querataro and was in fact L. diffusa. The alkaloid analysis of L. diffusa also provides an explanation of other controversial points in the history of peyote research. 6. An 80-year old sample of " mescal buttons" has been shown to still contain identifiable alkaloids, most notably mescaline.