Degree of Injury and Rate of Regeneration 529 
17, thirty-seven days after the operation. ‘Three sets of compari- 
sons similar to those of Experiment 8 may be made. 
a ‘The regeneration of the right fore-leg when it alone was 
removed was compared with the regeneration of the same organ: 
(1) when the other three legs were removed at the same time and 
(2) when the other three legs plus the tail were removed. ‘Two 
individuals are valid for comparison in each case. 
The two groups with the greater injury were alike in size of 
the legs and stage of development of the toes. When compared 
with the one individual in which the right fore-leg alone was 
removed all four individuals with additional organs removed 
have a larger right foreleg but there is no difference in the stage 
of developemnt of the toes. Difference when present is here in 
favor of the greater injury, though this comparison by itself would 
have but little weight. 
b The regenerated right hind-leg (No. 1051) and the regen- 
erated left hind-leg (No. 1057), one leg alone being removed in 
each case, were compared with the regenerated right or left hind- 
legs in cases with an additional injury involving 
1 All four legs (Nos. 1048 and 1054). 
2 Tail plus all four legs (Nos. 1049 and 1055). 
In stage of development of the toes these six individuals can 
be arranged as follows beginning with the one having the greatest 
development: 
1049, 1048, 1055 = 1054 = 1051, 1057. Individuals with an 
additional injury are evidently ahead of those with no additional 
injury. On the whole also the ones with the greater additional 
injury have an advantage over those with a lesser additional injury. 
c One individual with the tail alone removed had regenerated 
2.8 mm. of its tail, while of the two individuals with an addi- 
tional removal of the four legs, one had regenerated an equal 
amount (2.8 mm.) and the other only 2.3 mm. While insufficient 
for a definite conclusion the data favor the lesser degree of injury. 
Taking the five sets of experiments on salamander larve 
together the results on the whole evidently favor the individuals 
with additional injury. 
