212 



STUDIES ON RESPIRATION. V 



crease in CO2 output takes place in these concentrations before the 

 muscular movements are much affected. 



Fig. 2, shows the effect of the 3.65 per cent ether (Curve A) and the 

 effect of the 7.3 per cent ether (Curve B) on the CO2 output. With 



160 M in. 



Fig. 2. Curves showing the effect of 3.65 per cent ether (Curve A), and 7.3 per 

 cent ether (Curve B) on the CO2 production of frog tadpoles, and control in tap 

 water (Curve C, dotted line). The point marked on the abscissa indicates the 

 beginning of exposure to ether for Curves A and B ; 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 50 seconds for 

 Curve A, in 43 seconds for Curve B, and in 58 seconds for Curve C. Each 

 curve represents an average of six experiments. Probable error less than 2.5 per 

 cent of the mean. 



3.65 per cent ether a decrease of 81 per cent took place which was fol- 

 lowed by an increase; with 7.3 per cent ether a decrease of 50 per cent 

 occurred which was followed by an increase, the maximum of ac- 



