MOTOR RESPONSES 319 



sume that the higher the frequency of reversal, the more restricted the 

 movements of the ions toward the poles, and the shorter the period of 

 separation of positive from negative ions; and that the shorter this period, 

 the more restricted the union of the negative ions with hydrogen ions, 

 and the positive ions with hydroxyl ions. The more restricted these unions, 

 the less the increase in acidity in the plasmagel, and the less the increase 

 in alkalinity in the plasmasol, and the less the stimulating and the in- 

 jurious effect. The hypothesis, then, that the action of the electric cur- 

 rent on organisms is due to localized increase in acidity and alkalinity 

 in different regions of the cell is in full accord with the fact that the 

 effect in alternating currents varies inversely with the frequency. 



What bearing has all this on the problem concerning the observed con- 

 traction at the anodal side of amoebae subjected to direct current? 



Carlgren (1899), as previously stated, holds that this is due to elec- 

 troendosmotic extraction of water by the current, owing to negative 

 charge of the solid substance. However, the fact that the same phe- 

 nomenon occurs in alternating current, in which electroendosmosis is neu- 

 tralized, strongly indicates that Carlgren's conclusion is not valid. It also 

 seems to show that the anodal contraction in direct current must be due, 

 as appears to be the case in alternating current, to the action of the cur- 

 rent on the movement of ions. 



The evidence presented in reference to the effect of both direct and 

 alternating current on A. proteus indicates that the assertion of Bayliss 

 (1920), Weber and Weber (1922), Taylor (1925), and others that 

 electricity gelates cytoplasm, is misleading, for it shows that if an electric 

 current causes gelation in a cell, it probably always causes simultaneous 

 solation, each being confined to a portion of the cell. 



It was demonstrated above that this does not obtain for light. The 

 implication frequently found in the literature that the action of electricity 

 on protoplasm is the same as the action of light, appears therefore to be 

 erroneous. 



Heilbrunn and Daugherty ( 1931 ) found that if ammonium hydroxide 

 or chloride is added to the culture fluid, A. proteus becomes anopositive. 

 They maintain that the "protoplasmic granules" are ordinarily positively 

 charged and are consequently carried (cataphoretically) toward the 

 cathode, and that ammonium hydrate or chloride causes a change in 

 the charge to negative and a consequent reversal in the direction in which 



