Fig. 4. Assessment of Cl^– dependency for Na⁺ uptake by un-bled and bled L. stagnalis as tested under control (with NaCl) and treatment (with sodium gluconate or sodium sulfate) conditions. Each treatment medium contained 500 µmol l^–1 of Na⁺. Differences between un-bled and bled conditions within treatments were significantly different. There were no significant differences among Na⁺-treatment groups in un-bled or bled conditions. N=10 snails in all cases. Values are means ± s.e.m.