Chemotaxis and feeding behavior in Actinosphaerium, Amoebaa nd Ph ysarum are reviewed together with new results.Studies in giant amoeboid cells may provide new aspects on the mechanism of behaviors in amoeboid cells in general.
Actinosphaerium released attractant chemicals to prey organisms such as Tetrahymena. The attracted organisms were catched by adhering to axopods. The catched organisms were stored there until food vacuoles incorporated them into the cell body. The adhesiveness to prey organisms takes no decisive role in feeding behavior of Amoeba.
By applying a double-chamber method, chemotactic behavior of Amoeba was expressed as an averaged deviation, ΔP, in the motive force of protoplasmic streaming.ΔP exceeded by10cm H₂Oin chemotaxis as well as during spontaneous formation of uroid at the tail of Amoeba.
Intracellulat perfusion technique was applied to plasmodial strands of Physarum. Injected ATP, Ca²⁺and KCl had effects on the contractility and morphology comparable to those in extracted actomyosin such as ATPase activity, solubility, etc.Thus, dialized plasmodial strands will be an ideal system in studying chemoreception, transduction mechanism and regulation of contractility.

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[in Japanese]

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Cellulose acetate phthalate forms homogeneous blend with water-soluble polyethylene oxide. Reverse osmosis properties of membrane prepared from this blend was investigated using aqueous organic solution. This membrane is highly permeable to the hydrophilic solute, but impermeable to hydrophobic one. Regular solution theory was applied to the rejection of organic solute, assuming that it is primarily determined by the distribution of solute between the membrane and the aqueous solution. It indicates that this treatment can serve a basis for predicting solute rejection in reverse osmosis, if the membrane parameters are estimated reasonably.

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