CHAPTER V 



BEHAVIOR OF PARAMECIUM {Continued) 

 Reactions to Electricity and Special Reactions 



i. reactions to electricity 



The reactions of Paramecia to electricity are more complex than 

 those to other stimuli. This is owing to certain factors peculiar to the 

 action of the electric current, which interfere with the usual reaction 

 method. 



The gross features in the behavior under the action of electricity may 

 be seen as follows. The Paramecia are placed in a watch-glass or other 

 small vessel, and through the water containing them an electric current 

 is passed (Fig. 58, A). Unpolarizable electrodes should be used, though 

 the gross features in the reaction 

 may be observed with platinum 

 electrodes. A current such as is 

 produced by six or eight chromic 

 acid cells is needed. As soon as the 

 current begins to pass, all the Para- 

 mecia swims toward the cathode or 



Fig. 58. — A, General appearance of Paramecia reacting to the electric current. After 

 Verworn (1899). The current is passed by means of unpolarizable brush electrodes through 

 a cell with porous walls. The infusoria have gathered at the cathodic side. B, Magnified 

 view of a portion of the swarm as it moves toward the cathode. After Verworn. 



negative electrode. The swarm of infusoria all moving in the same 

 direction present a most striking appearance (Fig. 58, B). If while 

 all are swimming toward the cathode the direction of the current is 

 reversed, the Paramecia at once turn around and swim toward the 



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