A study is being made on the biosynthesis and metabolism of the following natural products in the indicated species: anatabine, nicotine, nornicotine, anabasine (Nicotiana species), coniine, gamma-coniceine (Hemlock), tiglic acid (Datura), gramine (Phalaris arundinacae), cocaine (Erythroxylon coca), psilocybin (Psilocybes cubensis), VLB, vindoline, catharanthine (Catharanthus rosea), delta1-tetrahydrocannabinol (Cannabis sativa), mimosine (Mimosa pudica). Use is made of precursors labeled with 14C, 13C, 3H, 15N. 13C-NMR is used to determine the positions of incorporation, especially of contiguous 13C atoms.