The art of plant cell culture has made remarkable achievements in the past 75 years. Cell cultures can be derived now from almost all plant species. These suspension cells prove to be an excellent source of enzymes both for primary and secondary metabolic pathways and present an ideal system for the study of the metabolic fate of xenobiotic substances in plants. Moreover, the synthesis of secondary plant products by cellsuspension cul tures is feasable. The production of natural substances used in medical therapy by means of cell cultures and fermentation techniques would offer considerable...