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VICTOR E. SHELFORD AND W. C. ALLEE 



d. Acid and ammonia 



The only two species of fishes used reacted to a combination 

 of acetic acid and boiled water (table 17, chart 3) in a manner 

 comparable to the response given to boiled water and increased 

 carbon dioxide. Since the reactions were so clearly parallel, no 

 further experiments were tried. This acidity was far greater 

 than when carbon dioxide was used (table 16) and since the 

 reactions were not markedly different, it is probable that the 

 fish react to some factor other than acidity in the case of the 

 carbon dioxide. Thus it would seem that the narcotic action 

 of carbon dioxide is more important in fish reactions than its 

 action as an acid. 



TABLE 17 



Showing the reactions of fishes to boiled water accompanied by acetic acid. Data 

 arranged as in preceding table. Controls in tap water. Experiments with gradient 

 between tap and treated water. 



The reactions to ammonia and boiled water are shown in 

 table 18. Although their reactions to boiled water were marked 

 Abramis did not react to boiled water and ammonia in a con- 

 centration which caused them to turn on their sides after an 

 hour or more. With the higher concentration this was true also 

 but more markedly since the fishes showed a time preference for 

 the high ammonia, though free to go back and forth. The three 

 Abramis, died after from nineteen to twenty-three minutes. The 

 only definite response given was the testing reaction which 

 occurred very often in both ends of the tank. A single Notropis 

 put in with the Abramis died after thirty minutes. 



