The origin of the 0 -methyl and the N -methyl group in the alkaloid ricinine has been determined. Carbon 14 labelled sodium bicarbonate sodium formate and C14 methyl labelled L-methionine and choline were administered to growing seedlings of Ricinus communis which elaborate the alkaloid ricinine. Methionine was the only metabolite that produced C14 activity in the alkaloid. The activity was located entirely in the methyl groups and the specific activity of the O-methyl and N-methyl group was found, within experimental error, to be identical. / Thesis / Master of Science (MSc)