VARIATIONS IN OXYGEN TENSION. 



141 



TABLE VI. 



EXPERIMENT 4. 

 Over 50 larvae examined in each case. 



A. Observed i Hour after Return to Sea Water. 



B. When observed 24 hours after return to sea water there was no motion 

 in any case except the control in sea water at 275 mm. which was normal. 



The parallelism with the control is striking. The toxic and 

 antitoxic effects of the increase of oxygen tension must balance at 

 this tension. 



V. In the last experiment the larvae were exposed to an oxygen 

 tension of 756 mm. (saturated). A stream of oxygen was 

 bubbled through a flask containing the isotonic NaCl for fifteen 

 minutes. The larvae were washed twice with this solution, then 

 were placed in it and oxygen bubbled through for five minutes 

 more and the flask closed. When some of the larvae were re- 

 moved at hourly intervals for return to sea water, oxygen was 

 bubbled through the remaining solution for one minute immedi- 

 ately after. 



TABLE VII 



EXPERIMENT 5. 

 Over 50 larvae examined in each case. 



A. Observed I Hour after Return to Sea Water. 



Solution. 



Time of Exposure. 



i Hour. 



2 Hours, 



3 Hours. 



Isotonic NaCl at at- 

 mospheric oxygen 

 tension 160 mm.. 3/4 larvae 

 bendings 



show 



No motion 



1/20 larvae show 

 bendings 



