THE BEHAVIOR OF INFUSORIA; PARAMECIUM 83 



the water, the animals all become pointed toward the cathode and swim 

 in that direction (Birukoff, 1899, Statkewitsch, 1903). This happens 

 even when the current is so weak that a single induction shock causes 

 no reaction. There is a summation of the effects of the successive 

 shocks until a reaction is produced (Statkewitsch, 1903). As most com- 

 monly used, induction currents pass alternately in opposite' directions. 

 The induced current in one direction is due to the closing of the circuit 

 in the primary coil, while the immediately following current induced in 

 the opposite direction is due to the breaking of the circuit in the primary 

 coil. The induced currents due to the breaking of the circuit are, as is 

 well known, more powerful than those produced by the closing of the 

 circuit. When both currents pass through the preparation alternately, 

 Paramecia react primarily to the stronger "break" currents. They 

 move toward the cathode of these stronger currents and are apparently 

 not affected by the weaker "make" shocks (Birukoff, 1899, Statke- 

 witsch, 1903 a). 



B. Reaction to the Constant Current 



If in place of induction shocks a continuous electric current is used, 

 the result is the same as was described in the last paragraph. The 

 Paramecia place themselves with anterior end directed toward the 

 cathode and swim in that direction (Fig. 58). 



From what we know of the behavior of Paramecium under the action 

 of other stimuli, we might suppose that the whole secret of this behavior 

 hes in the production of the avoiding reaction when the anterior end is 

 directed toward the anode. This reaction, continuing until a position 

 was reached where the anterior end was no longer stimulated, would 

 cause it to become directed toward the cathode. If the anode stimula- 

 tion still continued, now at the posterior end, the animal would continue to 

 swim forward toward the cathode, for to stimulation at the posterior end, 

 as we have seen, the animal responds by swimming forward. If this were 

 the method of reaction, the behavior under the electric current would 

 be of the same character as under the stimuli which the animal meets 

 in its natural existence. 



But a study of the exact movements of the animals shows that there 

 is present another factor which is peculiar to the action of the electric 

 current. To detect this the precise movements of the ciha under the 

 action of the current must be examined. The cilia themselves may be 

 directly observed in specimens placed in some viscous medium (see 

 Statkewitsch, 1904 a). Or the effective movements of the ciUa may be 

 determined by mingling with the fluid containing them a quantity of 

 finely ground India ink. By its aid the direction of the currents pro- 



