CO 2 IN RELATION TO REGENERATION IN PLANARIA. 115 



the same time the pieces are cut. This stock merely undergoes 

 a slight degree of starvation, while the pieces undergo starvation 

 for the same period and in addition the regulatory changes. 

 This is the procedure in experiments 1-5 and 8 in Table II., 

 but in experiments 6 and 7 the stock from which both pieces 

 and whole animals were obtained was starved seven days before 

 the pieces were cut. 



Each experiment in Table II., includes one lot of worms about 

 5 mm. in length which have developed from pieces cut ten to 

 fourteen days earlier ("regen." in table), and one lot of as nearly 

 as possible the same weight of worms 16-18 mm. in length, the 

 same size and from the same general stock as the worms from 

 which the pieces were cut, and kept without food for the same 

 length of time ("large" in table). In all cases the pH deter- 

 minations are made before feeding is resumed. 



Examination of the last column of the table shows that the 

 rate of CC>2 production is much higher in the small regenerated, 

 than in the large old animals, i.e., the regulatory processes have 

 been accompanied by an increase in rate of CC>2 production. 

 Moreover the rate is in general higher in the regenerated animals 



TABLE III. 



A COMPARISON OF SMALL ANIMALS REGENERATED FROM PIECES WITH LARGE 



ANIMALS OF THE SAME SIZE AS THOSE FROM WHICH THE PIECES WERE TAKEN. 



Fed three times. Determinations of pH at 18 C. 



than in the pieces of Table I. although the period without food 

 is in most cases longer in the latter than in the former and CO^ 

 production decreases during the early stages of starvation. 



Table III. records experiments similar to those of Table II. 



