The Contractile Vacuole of Amoeba proteus. III. Vacuolar Response to Phagocytosis1

ABSTRACT The reaction of the contractile vacuole of Amoeba proteus to single and multiple phagocytosis under controlled conditions has been studied. Fluid intake into the cytoplasm from the phagosomes induces secretion by the contractile vacuole of equivalent excess volumes:. Vacuolar response is rapid (200 sec) and may be initiated by increases of protoplasmic hydration of as little as 1%. Cytoplasmic uptake of fluid from the phagosome can occur against an osmotic gradient; thus some form of active transport is implied.