American banker and amateur ethnomycologist R. Gordon Wasson and his wife Valentina P. Wasson, a physician, studied the ritual use of psychoactive mushrooms by the native population in the Mazatec village Huautla de Jiménez, Mexico. In 1957, Wasson described the psychedelic visions that he experienced during these rituals in "Seeking the Magic Mushroom", an article published in the popular American weekly "Life" magazine. Later the same year they were accompanied on a follow-up expedition by French mycologist Roger Heim, who identified several of the mushrooms as "Psilocybe" species. Heim cultivated the mushrooms in France, and sent samples for analysis to Albert Hofmann, a chemist employed by the Swiss multinational pharmaceutical company Sandoz (now Novartis). Hofmann, who had in 1938 created LSD, led a research group that isolated and identified the psychoactive compounds from "Psilocybe mexicana". Hofmann was aided in the discovery process by his willingness to ingest mushroom extracts to help verify the presence of the active compounds. He and his colleagues later synthesized a number of compounds chemically related to the naturally occurring psilocybin, to see how structural changes would affect psychoactivity. The new molecules differed from psilocybin in the position of the phosphoryl or hydroxyl group at the top of the indole ring, and in the numbers of methyl groups (CH3) and other additional carbon chains.