THE RELATION OF THE AMOUNT OF TAIL RE- 
GENERATED TO THE AMOUNT REMOVED IN 
TADPOLES OF RANA CLAMITANS! 
BY 
MAX MAPES ELLIS 
Witn Turee Ficures 
INTRODUCTION 
The experiments furnishing the data employed in these obser- 
vations were made at the Zodlogical Laboratory of Indiana Uni- 
versity at Bloomington, during the years 1907-1908, on tadpoles 
of Rana clamitans (Latreille), and are a detailed study of a prob- 
lem presented in the Biological Bulletin, April, 1908. In this 
report it was stated that, “the rate of regeneration varies not only 
directly but proportionally with the distance the cut is removed 
from the tip of the tail.” This proportional relation was between 
the length of the part of the tail removed and that regenerated 
at the end of twelve days. The present experiments ascertained 
the relation between the amount removed and that regenerated 
at various intervals throughout the period of regeneration under 
several sets of conditions. The results may be stated in brief 
as follows: 
1 After a certain percentage of the amount removed had been 
regenerated, regeneration ceased entirely. (This percentage was 
always less than one hundred.) 
2 The same percentage of the part removed was regenerated 
by all tadpoles maintained under uniform conditions and of the 
same age, whether the amount removed was large or small; that 
is, the amount of regeneration at the time regeneration ceased was 
proportional to the amount removed. 
1 Contribution from the Zoélogical Laboratory of Indiana University, No. 106. 
Tue JourNAL or ExPERIMENTAL ZOOLOGY, VOL. VII, NO. 3. 
