2O6 E. J. LUND. 



In this series 0.711 c.c. of oxygen per 136 c.c. water represents 

 the concentration at air saturation at 20 C. The different con- 

 centrations of oxygen were obtained by properly mixing known 

 volumes of water of high oxygen content with oxygen-free water. 



At the end of the second period of three hours, each lot of 

 worms was again immediately transferred to a bottle containing 

 air-saturated water and left for a third period of three hours. 

 The rate of oxidation per gram per hour during this third period 

 was again determined. 1 



The only results from this experiment with which we are con- 

 cerned at this time are the rates of oxygen consumption per gram 

 per hour during the second period in different concentrations of 

 oxygen. These amounts of oxygen corresponding to the fourteen 

 different concentrations of oxygen are represented by the points 

 on the curve in Fig. 2. Each point is an average of the deter- 



.14 



f 



s 



J2 



w 

 w 



CL, .10 



Q 



W .0 8 



S, 



S3 

 en 



2. 

 O 



o, 



O 



.0.2 



.2 .4 A '8 .0 1.4 1.8 U.2 



CONCENTRATION, CC. Q PER 136 CC. WATER. 

 V 2 "2 



FIG. 2. 



minations on two lots of worms. From the curve in Fig. 2 it 

 will be seen that the oxygen concentration which begins definitely 



1 Many precautions and details of technique must be observed in such a rela- 

 tively complex experiment so that the three-hour period was selected as most 

 suitable. The writer is indebted to Miss Edna Wolf for valuable help in many of 

 the experiments reported in this paper. 



