REACTIONS OF IRISHES TO ATMOSPHERIC GASES 



235 



with oxygen 2.4 cc. per liter. The reactions were more marked, 

 as shown by the graph (chart 1, experiment 55, p. 233), but 

 when compared with other experiments, the .depressing effects 

 of the low oxygen and carbon dioxide are suggested. The fishes 

 showed greater disturbance in these experiments than in the 

 presence of more oxygen. 



TABLE 7 



Shoioing the reactions of fishes to a carbon dioxide gradient in boiled water. Oxygen 

 content of the water was from 1 to 2.4 cc. per liter. Other data as in table 6. 



EXPT. 

 NO. 



70 



70 A 

 84 

 84 A 



Hybopsis . 

 Hybopsis. 

 Abramis.. 

 Abramis.. 



Totals.... 

 Averages. 



CO2 



IN CC. 



PEH 



LITER 



CROSS- 

 ED CEN-' 



TER I TOTAL 

 TIME 

 A IN MIN. 



w 



50. Oj 8 



50.0 15 

 24.0! 36 



24.01 21 



275 



PER CENT OF 



TIME IN HALVES 



OF TANK 



Expt. I Control 



H 



L H 



98 54 



88 29 

 91 63 



TURNED BACK 



IN GRADIENT 



FROM HIGH (H) 



OR LOW (L) 



TEMP. 

 DEG. C. 



Expt. 



H L 



Control 



H L 



7.5 

 7.5 

 8.5 

 8.5 



TABLE 8 



Showing the reactions of fishes to a carbon dioxide gradient in experiments lasting 

 forty minutes or more. The nu7nbers from 1 to6 refer to six equal longitudinal divi- 

 sions of the tanks (indicated by the d's in fig. 2) when counted from the low (L) car- 

 bon dioxide end of the experimental tank and the corresponding end of the control 

 tank. The numbers beneath them represent the percentage of total individuals 

 (number of individuals times number of readings) recorded in each division at the 

 time of the readings. Readings were taken every five minutes. 



The results of several long experiments with readings every 

 five minutes are shown in table 8. Here the fishes showed a 



