VARIATIONS IN OXYGEN TENSION. 



139 



TABLE IV. 



EXPERIMEXT 2. 



Over 50 larvae examined in each case. 



A. Examined i Hour after Return to Sea Water. 



B. Same Larrcc Examined u Hours after Return to Sen U'atcr. 



Isotonic NaCl at at- 

 mospheric oxygen 



tension 1/50 larvae show 



bendings 



No motion 



No motion 



Isotonic NaCl at 

 slightly increased 



oxygen tension. . . 1/4 larvae show 1/12 larvae show i/S larvae show 

 bendings bendings bendings 



The toxicity is certainly markedly diminished by the slight 

 increase in oxygen tension. The effect is as marked as when 

 the tension was decreased. 



III. In this experiment the oxygen tension of the chamber was 

 raised to 230 mm. four hours before the experiment was started. 

 The isotonic NaCl in the beaker " E" was stirred vigorously at 

 intervals of fifteen minutes allowing the solution to come to equi- 

 librium at an oxygen tension of 230 mm. before the larvae were 

 introduced. The larvae were washed twice with this NaCL at 

 230 mm. oxygen tension, by pumping a few c.c. out through the 

 tube " T" and they were then introduced into the beaker " E" as 



