PHYSIOLOGY OF RECONSTITUTION OF PLANARIA LATA. 141 



higher than that of the entire headless animals. In Table III. the 

 length of time required for change from pH 7.9 to pH 7.3 is given 

 in hours and minutes for ten milligrams of headless animals and 

 pieces, as calculated from the actual weights and times. This 

 method of presentation is open to certain objections, but has the 

 advantage of brevity and clearness. Of the nine experiments in 

 Table III. five were with headless animals and eighths immediately 

 after section, four with headless and eighths twenty-four hours 



Table III. 



Time in Hours and Minutes Required for Change from pH 7.9 to 7.3 

 Calculated for 10 mg. from Actual Weight and Time. 



Headless. Eighths. 



Immediately after Section. 24 Hours a. s. 



10:36 4:10 



8:49 4:57 



10:30 4:10 



12:20 3:42 



12:40 9:20 



6:12 5:12 



10:40 4:53 



8:30 6:34 



7:22 4:44 



Mean, 9:48 4:51 5:51 



after section. In every case the time is much less for the pieces, 

 but is somewhat greater after twenty- four hours than immediately 

 after section. These data confirm the susceptibility data in show- 

 ing that rate of respiration in eighths immediately after section is 

 greatly increased over that of headless controls, and that after 

 twenty-four hours it is somewhat lower, but still far above that of 

 the controls. 



Changes in Oxygen Consumption Following Section. — Table IV. 

 gives the results of determinations of oxygen consumption made 

 by Dr. Hyman. In the first experiment wholes, headless, and 

 pieces are compared, in the others only headless and pieces, the 

 headless animals being used because they show less motor activity 

 than wholes. The pieces include both sixths and eighths from all 

 levels posterior to the head. Table IV. shows that oxygen con- 

 sumption is greatly increased in pieces immediately after section, 

 as compared with headless animals, and in the first experiment in 

 headless animals as compared with wholes. Twenty- four hours 

 after section the oxygen consumption is lower in some cases, higher 



