133] 



A'. 1 1 E < )!■ REGENER. I TION—ZELEN V 



133 



TABLE 74 



Amblystoma punctatum Series 4101-4540 

 Percentage increment per day of regenerating fore-leg at different periods for 



three degrees of injury 



Discussion 



The results obtained from the present study show that with certain 

 material it is possible to control disturbing factors so as to get data of 

 a sufficiently uniform nature for an analysis of the change in rate. Such 

 material was found in the tails of the tadpoles of Rana clamitans. The 

 analysis has yielded results which should be of value in a determination 

 of the factors involved in the stimulation of growth and more particu- 

 larly those concerned in slowing it down and finally bringing it to a stop. 

 The characteristics of the change in rate have been studied by means of 

 the curves of rate, of acceleration of rate and of percentage increments. 

 The rate is slow at first, increases rapidly until it is near a maximum at 

 about eight days; then decreases, at first rapidly and then more and 

 more slowly as zero is approached. The acceleration of rate is plus only 

 between the first two periods, i. e., up to the fifth day. After that it is 

 minus, reaching its lowest point at ten days. The percentage increment 



