MOTOR RESPONSES 323 



1927c). If this reaction obtains, the forward swimming toward the 

 anode is in full accord with Pfliiger's law. 



Kamada (1929) made a study of the correlation between the effect 

 of many different salts on reversal from forward to backward swimming, 

 and the direction of orientation in a direct current. He maintains that 

 some salts which induce forward swimming toward the anode do not 

 induce backward swimming. He consequently supports Bancroft's views. 



Kamada (1931) also maintains that in paramecia which are ano- 

 positive there is ciliary reversal at the anodal surface, in place of the 

 cathodal, and that with increase in current density this is modified in 

 various ways. The evidence he presents is, however, by no means con- 

 clusive. Further observations are therefore needed. 



Paramecia are most sensitive if the anterior end is directed toward the 

 cathode, less sensitive if it is directed toward the anode, and least sensi- 

 tive if the longitudinal axis is perpendicular to a line connecting the two 

 poles ( Statkewitsch, 1903; Kinosita, 1936). The same holds for Spi- 

 Yostomum (Kinosita, 1938a). 



Statkewitsch (1907) subjected to direct and to alternating currents 

 paramecia which had been stained with neutral red. He maintains that the 

 stained structures in them became violet (acid) in weak currents and 

 distinctly yellowish (alkaline) in strong currents. He apparently did not 

 observe any difference in the color at the two ends. In Kinosita's (1936) 

 experiments with paramecia stained with either neutral red or Nile blue 

 sulphate, the color of opposite ends differed. He says that the changes 

 in color observed show that the paramecia become acid at the cathodal 

 and alkaline at the anodal end, but that the alkaline portion rapidly ex- 

 tends forward and soon includes the entire body. 



There is consequently a diversity of opinion concerning the effect of 

 the electric current on the hydrogen-ion concentration of the cytoplasm in 

 Paramecium. This also obtains for other cells, since, as previously stated, 

 Kiihne maintains that cells of Tradescantia become acid at the anodal end 

 and alkaline at the cathodal end. Mast confirmed this, but could observe 

 no difference in this respect between the two ends in Amoeba. It is there- 

 fore obviously desirable to have further observations concerning this 

 problem, for it is theoretically very important. 



Kinosita measured the time required to make the anodal end alkaline 



