246 



VICTOR E. SHELFORD AND W. C. ALLEE 



while it is a definite reaction to the boiled water, the fact is not 

 evident from the table alone. Lepomis were indefinite in their 

 reactions, showing a slight preference for the boiled water in one 

 case and for the tap in another. Abramis showed a clear pref- 

 erence for the tap water or tap w'ater and gradient; Ameiurus 

 showed a preference for the boiled water in the second two 

 experiments. The Ambloplites showed the same reversal of 

 preference as was shown in the earlier experiments. Catostomus 

 showed a slight preference for the tap water while Etheostoma 

 showed a preference for the boiled water, as in one of the experi- 

 ments described above. When we note the decided preference 

 for one end or the other in the controls, we are justified in con- 

 cluding that on the whole, the reactions of the fishes to the 

 boiled water during the longer periods was indefinite rather than 

 clear-cut. 



TABLE 12 



Shoiving the reaction of the fishes from the high oxygen stock to a boiled water gradient 

 in experiments lasting an hour or more. Since some of the fishes tejided to rest 

 in the tap water end of the experiment and not to come into contact with the boiled 

 water, they were confined in the sixth of the tank nearest the boiled water end for 

 thirty minutes or more. At the beginnings of the readings they were released and 

 usually went back and forth in the tanks. For the distribution of the gradient in 

 these experiments, see figure 2, p. 227. The boiled water at the point of inflow, 

 contained less than 1 cc. of oxygen per liter. Nearer the surface the amount was 

 probably larger. Controls in tap water,' confined as experiments. 



