532 Journal of Comparative Neurology and Psychology. 



normal alkaline cultures are positive to alkalies (which cause liquefac- 

 tion), and negative to acids (which cause coagulation). The present 

 reviewer emphasized in his first paper on the reactions of Paramecium 

 (Journ. of Physiol., vol. 21, p. 268, p. 317) a result that is precisely 

 the opposite of this. Paramecia from alkaline cultures were found 

 to be negative to alkalies and positive to weak acids. From the re- 

 sults of literally thousands of experiments, many made since Greeley's 

 work appeared, I am compelled to reaffirm this result. Paramecia 

 then are positive to acids, which, as Greeley finds, are coagulative 

 in their effects. 



6. Paramecia in acid cultures are, according to Greeley him- 

 self, positive to acids. Yet acids cause coagulation under all circum- 

 stances, again according to Greeley. 



7. To strong alkalies Paramecia are under all circumstances 

 negative. Yet strong alkalies cause liquefaction. This shows that 

 liquefaction is not the ultimate determining feature in the positive 

 reaction. 



8. To all substances mentioned on page 11 of Greeley's paper 

 as causing liquefaction, Paramecia are negative, while to a number of 

 those listed as causing coagulation they are positive. 



Greeley's generalization is therefore in direct conflict with many 

 of the best known facts in the behavior of these organisms. It is no 

 doubt true that as a rule Paramecia avoid strongly coagulating agents, 

 for they avoid most injurious agents, and coagulation of the protoplasm 

 is one of the commonest injuries produced by external agents. But 

 thev equally avoid agents that cause liquefaction beyond a certain 

 stage, and they react in the same way to many conditions that are not 

 known to cause either liquefaction or coagulation. 



The only basis on which Greeley's theory might give a plausible 

 generalization as applied to electrotaxis would be the following. It 

 might be said that liquefaction, produced at the cathodic end of the 

 organism, is connected in some way with the reversal of the cathodic 

 cilia. But under other circumstances the cilia are reversed when 

 there is no indication of liquefaction, as in swimming backward in a 

 strong acid which causes coagulation. 



The paper of Birukoff (7) is a defence of the theory that the 

 movement of infusoria to cathode or anode is due to a passive trans- 

 portation by the cataphoric action of the curient. Since Paramecia in 

 ordinary water go to the cathode, while in salt solution they go (accord- 

 ing to Birukoff) to the anode, the amount of electromotive force 

 developed on the bodies of the animals during the passage of the cur- 



