456 



GENERAL PHYSIOLOGY 



electrodes (Fig. 230), and a constant current be passed through 

 the liquid from two brush-electrodes laid upon the clay pieces, at 

 the moment of making all the Paramcecia place themselves with 

 the anterior poles of their bodies toward the kathode, and swim 

 freely toward the latter in a dense crowd. In a few seconds the 

 anode is wholly deserted, and at the kathode there is a dense swarm, 



FlQ. 230. — Galvanotaxis of Paramreciwm. The arrow indicates the direction in which the Pa7'aiiioe(a 

 are swimming ; in B all have collected at the kathode. A Microscopic, B, macroscopic 

 picture. 



which remains as long as the circuit is closed If now the current 

 be reversed, so that what was before the anode becomes the kathode, 

 and vice versa, the whole swarm rushes over in one mass to the 

 opposite side, and collects, as before, at the kathode. This experi- 

 ment, which because of the great exactness of the reaction is very 

 fascinating to the observer, can be repeated as often as desired 



