The timeline is just a bit incomplete. Sir William Brooke O'Shaughnessy brought "Indian Hemp" [aka "Gunja"] to Western medicine in the early 19th century. It was a major portion of 19th century medication. It was included in the United States Pharmacopoeia through Edition XI, c.1935. As to how Cannabis came to be missing from U.S.P. Edn. XII-- You need to understand Anslinger. It wasn't "science" by a LONG stretch. It was the unconstitutional [Leary] "Marihuana Tax Act", which was replaced with the even worse Controlled Substances Act on Nixon's insane watch [read the tape transcripts]. "Schedule I Cannabis" is a damned lie that needs to be repudiated, NOT enforced. Richard P Steeb, San Jose California