216 



E. J. LUND. 



THE RATE OF CO 2 PRODUCTION IN THE 

 ABSENCE OF FREE OXYGEN. 



The rate of carbon dioxide elimination by Planaria was deter- 

 mined by the use of a modification of the method described 

 some time ago by Lund ('19). An important improvement in the 

 method was brought about by washing the bottles with a stream 

 of CO2-free air, after the animals were placed in the bottles, thus 

 doing away with the correction for CC>2 present in the air at the 

 beginning. Where CC>2 production was determined in the 

 absence of oxygen the bottles were washed out with hydrogen. 

 All titrations were performed without removing the stopper from 

 the bottle, by means of the simple expedient of boring two holes, 

 one on each side of the bottle. These holes were fitted with 

 stoppers and titration was carried on througTi one of these small 

 openings. This procedure simplifies the method and increases 

 its accuracy. The method has been used extensively in this 

 laboratory and has proven itself to be satisfactory, especially 

 when periods of two to three hours or more are used and com- 

 parative results are desired. 



Table VI. gives the results of an experiment where twelve lots 



TABLE VI. 



Planaria starved and kept at 20 C. 38 days before experiment. Temperature 

 during experiment 21 C. Twelve bottles with 50 animals in each. Blanks 

 run as controls are not given in the table, i c.c. N/ioo HC1 equivalent to 

 o.m c.c. CO2. 



