REACTIONS OF FISHES TO ATMOSPHERIC GASES 



243 



experiment performecl the experimental fishes tried the boiled 

 water three times during the first eight minutes. During the last 

 half of this period they showed some disturbance in excess of that 

 shown in the control, by rising to the surface and opening the 

 mouth. At the end of eight minutes the fishes showed their 

 first tendency to turn back at the center. After trying the 

 boiled water three times more, they began turning quite regu- 

 larly. This w^as continued twenty-six minutes with trials of the 

 boiled end being made every five minutes. The trials were 

 accompanied by some of the typical avoiding reactions, especially 

 by rising to the surface until the fins protruded. 



The graph of the reaction of Notropis (experiment 2, table 11) 

 showed less definite turnings than Hybopsis or Lepomis and 



_». Ay\ Y-* 



TABLE 11 



Showing the reaction of fishes from the high oxygen slock to a boiled water gradient. 

 The meaning of abbreviations, et cetera, is essentially as in table 6. p. 230. Controls 

 in tap water. Gradient between tap and boiled. 



1 No reaction to the gradient. 



- The fishes first encountered the boiled water which depresses the general activ- 

 ity of Ambloplites, p. 245. 



^ Two N. atherinoides were included in the experiment here by mistake, which 

 may account for a more definite reaction than was shown in table 15, experiments 

 77, 77 A and 79, where no atherinoides occurred. 



