Influx and efflux by leaves ofVallisneria spiralis

Summary A critical survey is given of the active uptake processes in order to have a basis for comparing the passage through the plasmatic membranes by non-electrolytes and by electrolytes (aminoacids and salts).According to Höfler's Two pathways theory the lipid path introduces lipophilic substances by diffusion through the lipids and lipoproteins of the membranes and the cytoplasm into the vacuoles. The other pathway leads non-lipophilic substances through pores in the membranes and is more susceptible to outer and inner conditions influencing the rate of permeation through the pores.Collander assumed that as a consequence of the presence of lipids in the cell membranes their permeability is so small that non-lipophilic substances enclosed in the different compartments of the cell do not show a noticeable efflux.The object of this investigationwas to establish whether inVallisneria leaves an influx of salts (chloride ions) occurs without a simultaneous efflux.In normal healthy tissue permeability of the plasma-membranes is so low that no efflux can be shown during 22 hours' uptake.For measuring the presence or absence of efflux of chloride ions during uptake a method was developed comparing the amount of labelled chloride ions absorbed with the increase of the total amount of chloride ions estimated by chemical methods.