2I 4 



E. J. LUND. 



TABLE IV. 



All Planaria starved 26 days before experiment. Temp. 20 C. 7 days before and 

 during experiment. 18 animals in each bottle. 



to the increased rate of oxygen consumption during the third 

 period, as that found in the whole animals used in Tables III. 

 and IV. The absolute increase during the third period, among 

 the different experiments, is not accounted for by any difference 

 in the length of the starvation periods of the animals previous 

 to the experiments, for these were the same. On the other hand, 

 any differences in motor activity which may have occurred in 

 the different experiments do not seem to me to give any adequate 

 physiological explanation of the effect. The magnitude of the 

 effect of movement on the respiratory exchange may be inferred 

 from certain observations on Planaria agilis made by Allen ('19, 

 I.). There remains the alternative explanation, that the increase 

 in oxygen consumption after living in low oxygen concentration 

 is due to the oxidation of lower fatty acids or other by-products 



