Fig. 3. Effects of microtubule inhibitors on the rate of active ammonia excretion across isolated perfused gills of the shore crab Carcinus maenas measured under initial conditions of symmetrical concentrations of NH₄Cl (100 µmol l^-1) in the external and internal baths. (A) Basolateral application of taxol (10 µmol l^-1) (N=6). (B) Basolateral application of thiabendazole (Thia.) (0.2 mmol l^-1) (N=6). Data represent means + S.E.M.