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Notes: Summary 1. Amoeba proteus orients very definitely in a galvanic current and moves toward the cathode. 2. If the anterior end is directed toward the cathode when the circuit is made there is increase in rate of streaming beginning at the anterior end and progressing toward the posterior end. If the current is weak, this increase is slight, if it is strong the anterior end spreads out and the posterior end contracts, if it is still stronger the amoebae disintegrate, beginning at the posterior (anodal) end. 3. If the posterior end is directed toward the cathode when the current is made the rate of streaming decreases beginning at the posterior (cathodal) end. If the current is not too weak retardation in streaming is followed by reversal in the direction of streaming at the posterior end while it continues in the opposite direction at the anterior end. If the current is strong the final effect is the same as it is with the anterior end directed toward the cathode, i. e. the amoebae disintegrate, beginning at the anodal surface. 4. In reactions to electricity, as in reactions to light, there is no specific threshold and the “all or none law” does not hold. The responses are due primarily to the solating action of the current on the plasmagel on the side directed toward the cathode and contraction of the plasmagel in adjoining regions. The nature of the response depends upon the extent of solation which in turn depends upon the density of the current and the time it acts. 5. Contraction at the anodal side accompanied by expansion at the cathodal side is due to gelation at the anodal side and electroendosmotic transfer of water from this side to the opposite side. 6. Rupture at the anodal side is due to irreversible gelation of the plasmagel with loss of water, making it so friable and weak that it readily breaks. This may be augmented by pressure against it, owing cataphoretic movement toward the anode of negatively charged granules. 7. Solation is due to accumulation of positive ions at the cathodal side, union of these ions with hydroxyl-ions in the presence of water and migration toward the anode of the hydrogen-ions liberated, resulting in increase in alkalinity at the cathodal side. 8. Gelation is due to accumulation of negative ions at the anodal side, union of these ions with hydrogen-ions in the presence of water and migration toward the cathode of the hydroxyl-ions liberated, resulting in increase in acidity at the anodal side. 9. In the epidermal cells of the leaves of Tradescantia which contain a natural indicator it can be clearly seen that the galvanic current causes increase in alkalinity at the cathodal end and increase in acidity at the anodal end. 10. In alternating current Amoeba proteus orients and moves at right angles to the direction of the current. 11. Viscosity increases at the two sides facing the poles and decreases in the central portion. This results in marked contraction of the two sides, forcing the central portion out in the form of pseudopods in either direction at right angles to the direction of the current. Later one of these pseudopods is retracted and the organism moves in the direction of the other. 12. If the current is strong the amoeba breaks at one or both surfaces facing the poles, after which the plasmasol usually flows out but the granules do not move toward the poles, cataphoresis being neutralized. 13. Increase in viscosity is due to localized accumulation of negative ions and union of these with hydrogen-ions resulting in increase in acidity. Decrease in viscosity is due to localized accumulation of positive ions and union of these with hydroxyl-ions resulting in increase in alkalinity. The process of accumulation depends upon difference in the rate of movement of positive and negative ions in a viscous medium and chemical union or electrostatic stabilization. 14. In both direct and alternating current the amoebae do not disintegrate if the surrounding medium is acid, no matter how strong the current may be. 15. The conclusion reached by various authors that the electric current causes increase in viscosity of cytoplasm is misleading. It probably always causes decrease in viscosity in some portions of cells and simultaneous increase in others. 16. Amoeba dofleini does not respond to the electric current. It does not disintegrate and no marked changes in viscosity were observed in it.