Degree of Injury and Rate of Regeneration 535 
eration with the length of the molting period. A study of the 
problem has revealed a very complicated interrelation of age 
molting time, degree of injury, rate of growth and rate of regen- 
eration. On the whole the specific amount of regeneration per 
molting period as a unit is more constant than the amount per 
day, other factors being alike. For this reason in the majority 
of the experiments the molting period is used as the unit." 
Notwithstanding their molting habit Crustacea have some very 
distinct advantages in a study of the problem in hand which 
partly offsets the disadvantages. The presence of a definite 
breaking joint in the chele makes it possible to be sure of the 
constancy of the level of regeneration. Furthermore Crustacea 
can be readily preserved after the completion of an experiment 
without danger of shrinkage and measurements can be more 
accurately made on them than on living animals. 
1 The Fiddler-crab, Gelasimus pugilator™ 
In the male fiddler-crab one of the two chelz is much larger 
than the other. In the female both are small and of equal size. 
The following plan of experiment was followed: ’ 
A Experiments on Males 
Set a Large chela alone removed. ‘Twenty individuals were 
kept for sixty-two days. 
Set b Small chela alone removed. ‘Ten individuals were kept 
for sixty-two days. 
Set c Both chelea removed. ‘Ten individuals were kept for 
sixty-two days and eighteen others for forty-two days. 
B Experiments on Females 
Set a One chela was removed in six individuals. 
Set b Both chelze were removed in three individuals. 
2 
16 See paper on Successive Regeneration. This journal, vol. vii, no. 3. 
17 Journal of Exp. Zodl., vol. ii, no. 1, p. 81. 
