204 E. J. LUND. 



consumption? (3) What is the relation of oxygen concentration 

 to the rate of carbon dioxide production and irritability in 

 Planaria agilis, which ordinarily would be considered aerobic? 



THE RELATION OF OXYGEN CONCENTRATION TO THE RATE OF 



OXYGEN CONSUMPTION. l 



\ 



The change in rate of oxygen consumption by Planaria agilis 

 while it is gradually consuming a given quantity of oxygen 

 dissolved in a given volume of water in a stoppered bottle is shown 

 in the curve in Fig. i . The data for the curve were obtained as 

 follows: Twenty-one bottles of equal volume were rilled with 



T~/ME: 



6" tO IS 3.0 25~ 30 3S ?t> ?f fo MRS. 



o 



S 3.0 



1 



uj 

 no 



FIG. i. 



water containing the same amount of oxygen. Ten animals of 

 equal size and the same history were placed in each bottle. At 

 the end of different time periods as indicated in the curve three 

 bottles were analyzed for oxygen content and the average taken 

 as the value which is plotted on the ordinate. The animals had 

 starved for over ten days previous to the experiment and therefore 

 had practically a constant rate of respiratory metabolism as 

 shown by Allen ('19, II.). 



1 The following is a part of certain studies on respiratory metabolism made 

 possible by a grant from the research fund of the graduate school. 



