Jennings, Behavior of Paramccimn. 495 



convection is competent to produce the effect ascribed to it on 

 the view of Pearl and Dale. With the strength of current 

 used, is the electrical convection sufficiently powerful to carry 

 the bodies of Paramecia, considered merely as pieces of ma- 

 terial of a certain size and weight, toward the anode at the rate 

 at which the Paramecia move backward ? Observation shows 

 that even smaller, non-living particles are not carried toward 

 either pole at any such rate. Further, Paramecia that have 

 been killed in ether, Chloroform, chloretone or formalin are not 

 moved to either electrode by the electrical convection. Biru- 

 KOFF (1899), who maintains the efficacy of electrical convec- 

 tion, endeavors to explain the fact last cited as follows. The 

 dead Paramecia do not remain suspended, but sink to the bot- 

 tom, and it is a necessary condition for the effective operation 

 of electrical convection that the solid particles in question should 

 remain in suspension. 



Obviously then in order to test this matter we must ar- 

 range experiments in such a way that the dead Paramecia shall 

 remain for some considerable time suspended. This is easily 

 done by placing them in a vertical tube, or by placing the slide 

 bearing the Paramecia in a vertical position. The electrodes 

 are then introduced at the upper and lower ends of the tube or 

 preparation. The Paramecia sink slowly through the water, 

 and thus remain a long time suspended, not being in contact 

 with any solid objects till they reach the bottom. 



With living specimens under these conditions the reactions 

 are identical with those in horizontal preparations. If a weak 

 current is used, the Paramecia hasten to the cathode, both when 

 this is at the upper, and when it is at the lower end of the tube. 

 If a stronger current is used, and the upper end of the prepa- 

 ration is made the anode, the infusoria swim backward against 

 the pull of the gravity to the anode, at the upper end. With 

 lifeless Paramecia on the other hand no such effects are pro- 

 duced. The dead animals simply sink steadily, whatever the 

 strength of the current, in spite of electrical convection toward 

 cathode or anode. 



Thus whatever it is that causes the Paramecia to move 



