534 Journal of Comparative Neurology and Psychology. 



fully for the movements to cathode or anode. -The turning into orien- 

 tation is likewise fully accounted for by the opposed movements of 

 cathodic and anodic cilia. Birukoff seems inclined to doubt the ob- 

 servations of LuDLOFF on this point, but these observations have been 

 confirmed by many investigators, and there is really not the slightest 

 difficulty in repeating them and perceiving their accuracy. What is 

 not accounted for is of course the observed effects on the cilia, partic- 

 ularly the cathodic reversal. It is here that further investigations 

 should take hold. 



Though Birukoff starts with the thesis that the movement is due 

 to cataphoric action, one finds that he admits in the course of his some- 

 what rambling paper various other factors. All difficulties with his 

 theory are solved by bringing in the conveniently vague "general irri- 

 tability" of the organism as an additional factor. He even admits, 

 toward the end, after many pages of argument against it, that the 

 "polar stimulation" of Verworn may have something to do with the 

 matter. One wonders finally whether Birukoff himself really be- 

 lieves that the movement is due to cataphoric action. 



It is of course possible that cataphoresis acts in some way as a 

 stimulus to produce the observed movements of the cilia, just as it is 

 possible that the neutralization of electric charges in the protoplasm 

 may be in some way connected with the movements. But neither 

 Greeley nor Birukoff have even so much as attempted to show how 

 this occurs. Little real advance in our understanding of the reaction 

 to electricity is to be expected from writers who ignore the fundamen- 

 tal phenomenon — the peculiar action of the current on the cilia. 



H. S. JENNINGS. 



