496 Journal of Coiiipamtive Neurology and Psychology. 



backward to the anode in a strong current is competent to lift 

 the animals against the force of gravity. The electrical con- 

 vection is not competent to produce this result. It is therefore 

 evident that the electrical convection is not the essential agent 

 in producing the movement of Paramecium backward to the 

 anode. The observations previously detailed show clearly what 

 is the agent producing this result. 



BiB.UKOFF (1899) held even that the usual movement to 

 the cathode was produced by the cataphoric effect, or electrical 

 convection. This had of course been disproved long before 

 the paper of Bikukoff was written. As an additional disproof, 

 we may note that the experiments just described show that the 

 electrical convection is not competent to produce the effect ob- 

 served in the movement to either cathode or anode. It is to 

 the movements 0/ t/ie a/i'a brought about by the electric current 

 that we must turn for the real factors producing the movements 

 to cathode or anode. 



Relations between Contact Reaction and Reaction to Elec- 

 tric Current. — In a previous paper (1897) I described what I 

 called an interference between the contact reaction ("thigmotax- 

 is") and the reaction to the electric current, and in a later paper 

 Putter (1900) considerably extended our knowledge of the 

 phenomena in question. The interference described consisted, 

 so far as Paramecium is concerned, essentially in the fact that 

 specimens showing the contact reaction respond less readily to 

 the electric current than do free specimens, and the response, 

 when it occurs, is intermittent. For Stylonychia, Putter held 

 that a further effect was evident, in the fact that thigmo- 

 tactic specimens take up a transverse position with respect to 

 the electric current, while the free specimens swim directly to 

 the cathode. 



I wish to bring out here certain further points in regard to 

 the interference between the contact reaction and the reaction 

 to the electric current. These are the following : 



I. In my previous paper I described this interference only 

 for the case of Paramecia in contact with a mass of detritus. 

 But the Paramecium need not be in contact with such a mass in 



