Reversal of motory polarity ofAmoeba proteus by suction

Summary When a glass capillary is introduced into the posterior body region ofA. proteus and its orifice is maintained inside the flowing mass of endoplasm, an applied suction force invariably initiates the reversal of streaming direction. This initial effect depends as well on the negative pressure value as on the terminal diameter of the pipette. Further transformations of configuration of pseudopodia are due to mixed effects of the direct application of sucking force and of the active response of amoeba to the new situation. When the sucking pipettes are applied to the outer cell surface, probably only a fraction of the negative pressure may be transmitted to the cell interior. The portion of cell periphery exposed to negative pressure acting from outside is still capable to contract. As a result, when amoeba as a whole is progressively sucked into the capillary, it manifests a clear active escape behaviour.Study supported by the Research Project II. 1 of the Polish Academy of Science.