Root cultures of Datura metel fed with tropine and tropic acid showed significant increases of tropane alkaloids as compared with control roots. This fact can be considered as the further proof, that the esterification of theese two compounds takes place in plants producing tropane alkaloids. The unknown alkaloid X was found in all samples of investigated roots. This base appeared in larger ammounts in roots fed, than in control ones. In dynamic experiments its increase was the largest during the first three days of investigation. This fact indicates that this base can be a precursor of hyoscyamine and is probably produced directly from tropine. The data obtained suggest the possibility of the reaction of epoxydation of hyoscyamine to scopolamine also in roots of Datura metel.