Jennings, Reactions to Electricity. 531 



liquefy the protoplasm. Attraction is accompanied by liquefaction, 

 repulsion by coagulation." This generalization Greeley applies to 

 all reactions, specifying particularly those to heat and cold and chem- 

 icals, as well as the reactions to electricity. 



How far are the facts in agreement with this generalization ? Is 

 it true that the animals always move toward liquefying conditions, and 

 away from those causing coagulation ? 



1. Greeley says that in the reaction to the electric current "a 

 dense gathering occurs about the negative electrode. In other words 

 they collect at that point in the electrical field where the conditions 

 are such as to induce a liquefaction of the protoplasm." Now it has 

 long been known that this gathering about the cathode is a secondary 

 and accidental result of the orientation produced by the current, and 

 it does not occur if the cathode is so placed that the organisms can get 

 past it. When this is possible, they swim behind it, into a region 

 where there is no current. There is thus no tendency to collect 

 where liquefaction is produced. All throrough work shows that the 

 effects of the current on the cilia, resulting in orientation, are the fun- 

 damental features, and any gatherings produced in one place or anoth- 

 er are a secondary result. 



2. In a stronger current the organism becomes oriented, but 

 does not move either to the region causing liquefaction, pr to that 

 causing coagulation. It remains in place, the cilia of the two halves 

 of the body driving it with equal force in opposite directions. 



3. With a still stronger current the animals swim backward to 

 the anode, though liquefaction is still caused at the cathode and coag- 

 ulation at the anode. This behavior squarely contradicts Greeley's 

 generalization. 



4. Greeley holds that the movement backward to the anode in 

 acids and osmotic solutions is in agreement with his theory, holding 

 that the electrical condition of the protoplasm has become reversed, 

 so that now liquefaction and coagulation occur under opposite condi- 

 tions. But Greeley does not show that under these conditions coagu- 

 lation occurs at the cathode, liquefaction at the anode, as his theory 

 requires, and no one has ever reported anything of the sort. Further 

 it is established that as soon as the organisms become acclimatized to 

 the solutions, they go to the cathode, as usual. There is no explana- 

 tion of this fact, on Greeley's theory. 



5. Greeley seems not to recognize that some of the supposed 

 facts on which he bases his generalization are contradicted by 

 the results of previous investigators. He says that Paramecia f ro m 



