AbstractBRIGGS, HOPE and ROBERTSON (1961) consider the uptake of electrolytes to be a combination of active and passive processes, causing simultaneous influx and efflux of salt ions.In this publication it has been shown, that inVallisnerialeaves the peripheral plasma membrane is non‐permeable to electrolytes. The continuation of this non‐permeability is essential for the efficiency of the active uptake process. The permeability of the membrane is increased by manipulation of the leaves and by changes in the ionic composition of the external solution. A consequence of the non‐permeability of the plasma membrane to electrolytes is the active uptake of ion pairs. Ion exchange between plasma and external medium is not involved in active uptake processes of resistant plants. The validity of these principles for active uptake of cations as well as for anions is treated in the discu