REACTIONS OF INFUSORIA TO ELECTRIC CURRENT 167 



to have a polarizing effect on the organism, resulting in the different 

 action of the cilia on the two halves. At the anodic half the current 

 is considered to cause a backward movement of the cilia, or "contractile 

 stroke"; at the cathodic half, a forward movement or "expansive 

 stroke" (Verworn, 1899; Ludloff, 1895). The precise cause of this 

 action is not given, but as supporting the possibility of this view, the 

 experiments of Kuhne (1864, page 99) and Roux (1891) on the polariz- 

 ing effects of the current may be cited. Kuhne showed that the violet- 

 colored cells of Tradescantia become under the influence of the electric 

 current red at the anodic end, green at the cathodic end, ■ — indicating 

 that the anodic end becomes acid, the cathodic end alkaline. Roux 

 showed that under the electric current the frog's egg becomes divided 

 into two halves of different color. Furthermore, the two halves of a 

 cell in the electric current become physically somewhat different, owing to 

 the cataphoric action. There is a tendency for the fluids of the body 

 to be carried to one end, — the cathodic, — while the solids are carried 

 to the other, — the anodic. As a result of such chemical or physical 

 polarization, or of both, it is then conceivable that the body of the in- 

 fusorian may become divided into two halves, differing in such a way 

 that the cilia act in opposite directions. On this view the backward 

 stroke of the cilia on the anodic half of the body is as much a specific 

 effect of the current as is the forward stroke of the cathodic cilia. Op- 

 posed to this view is the consideration that the action of the anodic cilia 

 is as a matter of fact not different from that in the unaffected animal, 

 and the further fact that the cathodic effect is limited, in a weak cur- 

 rent, to only the cathodic tip of the animal. If both the backward and 

 the forward positions of the cilia are specific effects of the current, it 

 is difficult to see why the former should prevail so strongly over the 

 latter in a weak current. On the other hand, if we consider the cathodic 

 action alone as a specific effect of the current, interfering with the normal 

 backward stroke of the cilia, then it becomes at once intelligible that 

 this interference should be least in a weak current, and should increase 

 as the current becomes more powerful. In producing its characteristic 

 effect chiefly at the cathode, the action of the electric current on in- 

 fusoria agrees with its action on muscle, as Bancroft (1905) has recently 

 pointed out. 



The most thorough study of the fundamental changes produced by 

 the electric current is that made by Statkewitsch (1903 a), and his con- 

 clusions are entitled to high consideration. Statkewitsch subjected Para- 

 mecia that had been stained in the living condition with certain chemical 

 indicators, — neutral red and phenol-phtalein, — to the influence of the 

 electric current. He found that the current caused chemical changes 



