110 



ILLINOIS BIOLOGICAL MONOGRAPHS 



[110 



rate is reached during the period between four and six days at three 

 of the levels and between six and eight days at the other three. The 

 rise in rate is very rapid and the decline also rapid. 



As discussed in the preceding section on the effect of the level of 

 the cut, the rate of regeneration increases with depth of the level and 

 the increase is such that in general the specific length or length regener- 

 ated per unit of removed length is approximately a constant. A reduc- 

 tion of the rates to specific rates therefore gives an opportunity for 

 averaging the different levels together. The resultant average is based 

 upon a sufficiently large number of individuals to give a considerable 

 degree of smoothness in the curve of rate. The data for specific rate 



2 nd 



5 7 9 11% 15% 



— >■ Days after the operation 

 Figure 53. Specific rates of first and second regenerations at different times 

 after the operation Rana clamitans Tail regeneration Upper figure, 

 second regenerations; lower, first regenerations. 



are given in Table 56. The average specific rates for all six levels to- 

 gether are 0.019 mm. during the to 4 day period, 0.066 during the 

 4 to 6 day period, 0.051 for 6 to 8 days, 0.033 for 8 to 10 days, 0.017 for 

 10 to 12i/ 2 days, 0.001 for 12y 2 to 18 days and —0.001 for 18 to 56 

 days. This change in rate is represented graphically in the upper part 

 of Figure 53. For the four deepest levels the averages are given in a 

 separate column of Table 56. They exclude the two lowest levels which 



