AN ANALYSIS OF THE RATE OF REGENERATION 
THROUGHOUT THE REGENERATIVE PROCESS? 
BY 
MARION L. DURBIN 
Wirtu Six Ficures 
The experiments upon which the present paper is based were 
undertaken with the object of obtaining a comparison of the rates 
of regeneration throughout the regenerative process. Spallan- 
zani,? the first to study the rate of regeneration, makes this state- 
ment concerning the legs of the aquatic salamander: “More- 
over, as natural legs take their greatest increase when they are 
still soft, and lengthen less when they begin to harden, the same 
thing happens in reproductions.” ‘It is necessary to note the 
following periods, at least when we speak of salamanders already 
come to their growth, viz: the considerable time, which passes 
after the cutting off of the leg, before the reproduction begins; 
its slowness in the first period; its quick progress afterwards; 
and lastly its tardiness when the leg begins to harden.” It is to 
be expected that the rate of regeneration of the tails of frog tad- 
poles will also show more or less regular change during the proc- 
ess. A study of this change should be of interest, (1) in compari- 
son with the curve of ordinary growth, and (2) as a help in isolat- 
ing the factors controlling the process of regeneration. ‘These 
experiments dealt with tadpoles of Rana clamitans (Latreille) 
which were more than nine months old. The principal interest 
is confined to the increase in the length of the regenerating tail 
since an attempt to study its volume was unsuccessful. ‘The rate 
1 These experiments were performed in the Zodlogical Laboratory of Indiana University during 
the school year 1907-1908. I wish to thank Dr. Charles Zeleny for his careful directions and many 
helpful suggestions which have enabled me to do this work. I am also indebted to Mr. Max M. Ellis 
for the use of the data referred to on p. 411, Fig. 5. The present paper is listed as No. 105 of the contri- 
butions from the Zodlogical Laboratory of Indiana University. 
2 Spallanzani (Lazaro) Abbé (1769). An Essay on Animal Reproductions. 
THE JourRNAL oF EXPERIMENTAL ZoOLoGY. VOL, Vii, No. 3 
