136 



ISAAC STARR, JR. 



to maintain the proper concentration and reduce the temperature 

 to room temperature before introducing the larvae. This pro- 

 cedure removes the oxygen almost entirely, for if alkaline pyro- 

 gallol is added to the solution after this treatment no color ap- 

 pears for an hour or more. The control solution, 0.52 NaCl at 

 atmospheric oxygen tension, was also boiled, air instead of 

 hydrogen being bubbled through. 



TABLE II. 



EXPERIMENT i. 

 Over 50 larvse examined in each case. 



A. Examined i Hour after Return to Sea Water. 



B. Same Larva: Examined 24 Hours after Return to Sea Water. 



Isotonic NaCl at at- 

 mospheric oxygen 

 tension . 



I larva showed All disintegrated All disintegrated 

 bendings. The 

 rest had disinte- 

 grated. 



Isotonic NaCl at re- 

 duced oxygen ten- 

 sion . . 



All larvae actively All disintegrated 

 motile 



I All disintegrated 



The antitoxic effect of the absence of oxygen is marked. This 

 was to be expected from Loeb's experiments on Arbacia eggs. 



II. To expose the larvse to 0.52 mm. NaCl with increased 

 oxygen tension, the simple apparatus pictured was employed. 

 The oxygen tension desired was obtained by running washed 

 oxygen from a tank into the chamber " A," driving the level oT 

 water inside the chamber down to a mark previously determined 



