Fig. 2. Net fluid movement in isolated perfused snake proximal renal tubules. Composition of solution in lumen and bath in terms of sodium and chloride and of substitutes for them is shown at sides of figure for each experiment. Each bar represents the mean ± S.E.M. (N=6-13) of net fluid movement with lumen and bath compositions shown (Dantzler, 1978; based on data from Dantzler and Bentley, 1978a).