424 Max Mapes Ellis 
tail cephalad. The piece removed was immediately measured 
under a microscope with an ocular micrometer and the exact 
amount removed ascertained. The measurements of the regener- 
ated parts were also made with an ocular micrometer, the living 
tadpole being placed upon a glass slide. The body length and 
tail length were taken with dividers and a steel rule. 
The significance of certain terms used is as follows: 
“Amount removed” is the length, in millimeters, of the part of 
the tail removed. | 
“Amount regenerated” is the length, in millimeters, of the 
part regenerated. 
“Per cent regenerated” is the per cent of the amount removed. 
DESCRIPTION OF EXPERIMENTS 
« Preliminary Experiment? 
The results of this experiment were mentioned inthe introduction 
of this paper as pointing out the present problem. ‘The table of 
averages is repeated here. “The term “rate of regeneration’”’ refers 
to the amount regenerated in millimeters, divided by the number of 
days during which the regeneration occurred. ‘This rate of regen- 
eration divided by the amount, in millimeters, removed gives the 
quantity termed “proportional rate.” 
TABLE 1 
AMOUNT RATE OF PROPORTIONAL 
REMOVED REGENERATION ’ RATE 
mm. mm. mm. 
7 0.24 0.034 
Io 0.34 0.034 
13 0.43 0.033 
7 0.19 0.027 
Io 0.26 0.026 
13 0.34 0.026 
This table shows that the absolute rate varied with the amount 
removed, and that this variation was proportional to the amount 
removed. ‘Two sets of tadpoles were used; hence the two divi- 
2 Biological Bulletin, April, 1908. 
