REACTIONS OF INFUSORIA TO ELECTRIC CURRENT 165 



can be disproved on other grounds. Statkewitsch (1903 a) shows that 

 dead or stupefied Paramecia that are suspended in viscous fluids are not 

 moved by cataphoric action, while living Paramecia in the same fluids 

 swim to the cathode. Dead or stupefied Paramecia placed in water in 

 a perpendicular tube through which an electric current is passed sink 

 slowly and steadily to the bottom, whatever the direction of the current, 

 while living specimens pass upward when the cathode is above. If the 

 anode is above and a very strong current is used, the living animals swim 

 backward to the anode, as described on page 98. They therefore move 

 upward against gravity, while dead or stupefied specimens with the same 

 current sink slowly to the bottom of the tube. It is thus clear that neither 

 the forward movement to the cathode nor the backward movement 

 toward the anode is directly due to the cataphoric action of the current, 

 for this action is not capable of producing the observed movements. 



The cataphoresis might of course act in some way as a stimulus to 

 induce the observed active movements of the cilia. This is apparently 

 the view toward which Carlgren (1899, 1905 a) and Pearl (1900) are 

 inclined. This is of course a theory of a radically different character 

 from that which we have been considering. Just how this effect would 

 be produced through the known physical action of the current has not 

 been shown. 



Coehn and Barratt (1905) hold that Paramecia in ordinary water 

 become positively charged, through the escape into the water of the 

 negative ions of the electrolytes which the body holds, while the positive 

 ions are retained. As a result of this positive charge, the electric cur- 

 rent tends to carry the animals to the cathode; the infusoria are held 

 to follow this tendency and swim with the pull of the current toward the 

 cathode. In a solution containing more electrolytes, it is held that the 

 positive ions escape from the protoplasm ; hence the animals become 

 negatively charged. They therefore pass to the anode when placed in 

 a solution of sodium chloride or sodium carbonate. This theory leaves 

 unaccounted for precisely the essential feature of the reactions, the 

 cathodic reversal of the cilia. It likewise fails to account for the fact 

 that as the current becomes stronger the passage to the cathode ceases 

 and the animals begin to swim backward to the anode, and for the 

 further fact that individuals which have become accustomed to a solu- 

 tion of sodium chloride or carbonate no longer swim to the anode, but 

 pass to the cathode as usual. These facts appear to be absolutely fatal 

 to the view under consideration. Little is to be hoped of any theory 

 that neglects what is clearly the fundamental phenomenon in these 

 reactions, the cathodic reversal of the cilia. 



Another theory has held that the reaction to the electric current is 



