MARIAN IRWIN 217 



With tadpoles and Fundulus embryos the effect of ether at a con- 

 centration of about 0.73 per cent is reversible. The Fundulus em- 

 bryos recover, as shown by their subsequent growth and normal de- 

 velopment. The tadpoles also recover, as shown by their subsequent 

 normal respiration. The increase in carbon dioxide production in 3.65 



60Mi%. 



Fig. 5. Curves showing the effect of 0.73 per cent ether (Curve A), 3. 65 per cent 

 ether (Curve B), and 5.48 per cent ether (Curve C), on the CO2 production of 

 Fundulus embryos, and control in tap water (Curve D, dotted line). The point 

 marked on the abscissa indicates the beginning of exposure to ether for Curves 

 A, B, and C; 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 128 seconds for Curve A, in 119 seconds for Curve B, 

 in 176 seconds for Curve C, and in 111 seconds for Curve D. Each curve rep- 

 resents an average of six experiments. Probable error less than 2 per cent of the 



and 7.3 per cent ether is accompanied by irreversible changes leading 

 to death. If Fundulus embryos were removed from the ether about 

 75 seconds after the increase began in 3.65 per cent ether, they failed 

 to recover. In tadpoles the recovery is no longer possible 47 seconds 

 after the increase has begun. In frog eggs similar results were 

 obtained. 



