Jennings, Behavior of Paramecmni. 489 



trie current is the contrasted action of the cilia in the cathode 

 and anode regions of the body (Fig. 14), as described by Lud- 

 LOFF (1895). But it is to be observed that the action of the 

 ciUa in the anode region is identical with that which occurs un- 

 der the influence of any other stimulus. The work of Roesle 

 (1902) and Statkewitsch (1903) shows that under induction 

 shocks the stimulation is primarily at the anode, and that the 

 effect of this stimulation is similar to that of stimulation by 

 other means; the cilia are reversed for a short time, so that the 

 animal swims backward ; then it starts forward in a new direc- 

 tion (Statkewitsch, 1903). Under the constant current, after 

 the circuit has been closed and the conditions have become con- 

 stant, the anode cilia are directed backward, as under usual con- 

 ditions, so that so far as they are concerned the animal swims 

 forward in the normal way. It is then in the continued rever- 

 sal of the cathode cilia that the peculiar action of the current 

 manifests itself; these cilia oppose the normally acting anode 

 cilia, giving rise to the conflict in direction of turning and of 

 progression that is so striking a factor in the reactions to elec- 

 tricity. Ludloff's account of this peculiar action of the cathode 

 cilia is excellent, but certain points brought out by Ludloff 

 are not included in the schema usually copied from his work, 

 and this has given rise to certain misconceptions. This has 

 been shown in the recent valuable paper of Statkewitsch 

 (1903 a). My own results confirm those of Statkewitsch on 

 this point ; since they were obtained quite independently of the 

 work of Statkewitsch,^ and by a different method of experi- 

 mentation, I will set them forth. The essential point is that 

 the reversal of the cilia in the cathode region of the body does 

 not typically include just half the body, as is usually set forth. 

 On the contrary, it begins in a weak current with a very slight 

 effect limited to the point of the cathode end of the body, and 

 as the current becomes stronger it spreads gradually backward, 

 until it finally includes almost the entire body. Statkewitsch 



1 My experimental work was completely finished and the first draft of this 

 paper written when Statkewitsch's paper appeared. 



