MARIAN IRWIN 219 



per cent and 7.3 per cent ether, an increase in the carbon dioxide 

 production takes place, the effect being irreversible. This is differ- 

 ent from the effects usually found in plants. 



SUMMARY. 



1. The experiments on frog tadpoles show that with 0.15, 0.37, and 

 0.55 per cent ether solutions there is a decrease in CO2 output. The 

 effect is reversible. With these concentrations the breathing move- 

 ments and body movements remained normal during the experiment. 

 In 3.65 and 7.3 per cent ether there is a decrease of respiration fol- 

 lowed by an increase which in turn is followed by a decrease. The 

 increase may reach about three times the normal rate. The in- 

 crease in the CO2 output is accompanied by the peeling of the skin. 

 The effect is irreversible. , 



'2. Experiments on an aquatic insect, Dineutes assimilis Aube, 

 show that in 7.3 per cent ether there is a decrease followed by an in- 

 crease which in turn is followed by a decrease. There is no apparent 

 disintegration of structures in the organism accompanying the in- 

 crease. The effect is irreversible. 



3. The experiments on frog eggs with 7.3 per cent ether show a re- 

 sult similar to that found in aquatic insects. 



4. Experiments on Fundulus embryos show that with 0.73 per cent 

 ether there is a reversible decrease in the rate of CO2 production. 

 In 3.65 per cent ether there is a temporary decrease followed by an in- 

 crease, after which the rate begins to fall off. In 7.3 per cent ether 

 there is an immediate increase amounting to 307 per cent which is 

 followed by a decrease. The increase in the 3.65 and 7.3 per cent 

 ether is accompanied by irreversible changes leading to death. The 

 decrease found in 0.73 per cent ether is not sufficient to cause narcosis, 

 as is shown by experiments on which the same decrease is produced 

 by lowering the temperature. 



5. These experiments show that narcosis is not due to asphyxia. 

 The action of anesthetics is due to some other cause than the effect 

 on respiration. , 



There is a difference between the animals studied and the plants 

 described in this series of articles, since in animals the increase in the 



