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VICTOR E. SHELFORD AND W. C. ALLEE 



in low oxygen. Abramis was apparently affected by the con- 

 tinued exposure to low oxygen. In the high oxygen stock, there 

 was a definite apparent time preference for the tap water while 

 here in three of the four trials the fish gave an apparent time 

 preference for the boiled water. In one experiment the turnings 

 were more numerous from the tap than from the boiled water. 

 When all the turnings are considered as of the same value as the 

 time preference, positive reaction is markedly less than that 

 shown by the high oxygen stock. The same thing is shown in 

 the long experiments (table 14). This difference in reaction may 



TABLE 14 



Showing the reactions of fishes from the low oxygen stock, to a boiled water gradient. 

 Data arranged as in the preceding tables. Compare ivith table 12, p. 2^6. These 

 fishes were confined in the tap water and for 30 minutes or more. Controls in tap 

 water. 



be due to an acclimatization to low oxygen. It is fully as prob- 

 able, however, that the change was due to the fact that in the 

 low oxygen aquarium the fishes formed the habit of .swimming 

 much of the time at the surface and thus in the experiment the 

 gradient would not be noticed. This habit of swimming at the 

 surface was necessary because the fishes died if confined below 

 the surface of low oxygen water. 



We had only a low oxygen stock of Umbras for boiled water 

 experiments but their reactions are similar to those given by 

 other fishes from high oxygen. Low oxygen Ameiurus showed 

 about the same preference for the tap water in one watched 

 experiment as did the high oxygen stock. A limited number of 

 observations in the glass boxes showed the high oxygen stock 



