Rate 



100-f 



% 



>-.-» 



50- 



J 



~?C 



'OMin. 



Fig. 3. Curves showing the effect of 7.3 per cent ether (Curve A) on the COj 

 production of an aquatic insect {Dineutes), and control in tap water (Curve B, 

 dotted line). The normal rate is taken as 100 per cent. The point marked 

 on the abscissa indicates the beginning of exposure to ether for Curve A; previous 

 to this, the material was in tap water (horizontal part of curves). The normal 

 rate (which is taken as 100 per cent) corresponds to a change from pH 8.0 to pH 

 7.7 in 38 seconds for Curve A and in 41 seconds for Curve B. Each curve repre- 

 sents an average of six experiments. Probable error less than 2.5 per cent of the 



mean. 



214 



