RESPIRATORY METABOLISM OF PLANARIA AGILIS. 213 



1.86, 1.41, 1.50 and 1.37 for bottles I, 2, 3 and 4 respectively. 

 It might seem that the previous life in low oxygen did have an 

 effect which resulted in slightly decreasing the acceleration in 

 aerated water. This therefore, so far as it goes, confirms the 

 inference from the comparison of the curves in Figs. I and 2 

 above in respect to the difference in the limiting concentrations 

 of oxygen in the two methods of experiment used in obtaining 

 the two curves. 



A second question upon which the experiment given in Table 

 III. was intended to throw light is: What effect does the state 

 of nutrition have upon the magnitude of the increase of oxygen 

 consumption during the third period? The animals of lot B 

 were treated exactly like those in lot C except that those in lot 

 C were fed liver about forty-two hours before the beginning of 

 the first test period. The expected marked rise in oxygen con- 

 sumption occurs in lot C during the first period. This rise 

 persists during the third period but it will be noted that the 

 increase in rate during the third period over that in the first 

 period is only 0.87 c.c. per gram per 24 hours in the fed lot C 

 as compared to 1.54 c.c. per gram per 24 hours in the starving 

 lot B. The average increase in lot C is 17 per cent, while in lot 

 B it is 51 per cent. This question was tested further by com- 

 paring fed and starved animals. Table IV. is self-explanatory. 

 The animals in bottles numbered 5 to 8 were fed beef liver 

 twenty-four hours previous to the experiment. The results again 

 show a greater increase of oxygen consumption by the starved 

 than by the fed animals, during the third period. 



It was suspected that the increased rate of oxygen consumption 

 during the third period might be due to increased motor activity 

 by the animals during the third period. Accordingly in an 

 experiment, the results of which are given in Table V., the heads 

 of both starved and fed animals were cut off after feeding, 

 that is, about 24 hours before the beginning of the experiment. 

 All the data are calculated on the basis of the weights of the 

 animals before feeding after subtracting the weight of the heads 

 which were removed after feeding. The results on such decap- 

 itated fed and starved animals show the same relations in respect 



