282 



W. C. ALLEE 



holds whether the isopod is coming out from or going under the 

 effect of the depressing agent. 



This same state of affairs is shown in the tables of the pre- 

 ceding paper^ which deal with the effects of depressing agents. 

 The data presented in these tables may be illustrated by the 



X 



Chart 6 The rheotactic and concussion responses of isopod no. XIV. For 

 methods of charting, see chart 1, p. 275. 



following responses taken from table 15 which shows the effect 

 of high carbon dioxide and low oxygen upon rheotaxis in stream 

 isopods. The results are in percentages of 80 trials: 



1. Eighty-nine per cent positive; 7 per cent negative; 4 per 

 cent indefinite. 



5 Allee '12, tables 11, p. 299; 15, p. 310; 16, p. 312; 17, p. 315; 18, p. 315; 19, p. 316; 

 and 20, p. 318. 



