142 



P. B. SIVICKIS. 



in others, than immediately after section, and increase is more 

 frequent in the pieces than in headless animals. Pieces of P. 

 dorotocephala also show a similar increase in oxygen consumption 



Table IV. 



Oxygen Consumption of P. lata: Whole Animals, Headless, and Sixth 



and Eighth Pieces Immediately and Twenty-four Hours after 



Section. Calculated in Cubic Centimeters of Oxygen 



Consumed per Gram in Four Hours. 



Calculations at 20 C. 



in some cases (Hyman, '22). In this respect the data on oxygen 

 consumption apparently disagree in part with those on C0 2 pro- 

 duction and susceptibility. The reasons for this apparent dis- 

 agreement are not as yet certainly known, but it seems probable 

 that nutritive condition and growth at the cut surfaces which is 

 appreciable within twenty-four hours are the factors chiefly con- 

 cerned. 



Time of Head Determination. 



It has been shown that in P. dorotocephala the head frequency 

 characteristic of a certain length of piece at a certain level is deter- 

 mined within a few hours after section to such an extent that it is 

 only slightly or not at all altered by decreasing the length of piece 

 after that time (Child, '14c?). The experiment to test this point 

 gives essentially the same results in P. lata, except that the differ- 

 ences in head frequency in long and short pieces are less than in 

 P. dorotocephala. Fig. 25 shows the pieces used in the experi- 

 ment. A large number of long pieces are cut with anterior ends 



