TOXICITY OF ACIDS TO CILIATE INFUSORIA 



449 



Acetic and butyric were tested at 10° and not at 12^ 



properties of a series of acids are similarly varied with dilution, 

 as my experiments indicate, then very few of the experiments 

 so far available can be fairly compared, since most observers 

 report only one concentration, which may lie anywhere between 

 1 and 0.00001 N. 



B. Specific differences 



In order to study specific differences adequately, precautions 

 must be taken to keep all the material under identical conditions. 

 Uniformity was insured in the present experiments by using a 

 mixed culture and testing the organisms all together. Graph 2 

 shows typical results; full data are given in table 1. 



At whatever concentration they are tested, no matter what 

 the acid, Paramoecium is much less resistant than Euplotes. 

 Some specific difference is also observable between Paramoecium 



