522 Charles Zeleny 
5 Larve of Amblystoma opacum. Nos. 2000-2031 
A mass of eggs with the adult coiled over them was collected on 
October 1, 1906. The hatched salamanders were put into indi- 
vidual dishes about December 15 to avoid cannibalism. Four 
kinds of operations were made on December 15 with eight indi- 
viduals for each kind. ‘The essential precautions to avoid error 
as described on pp. 514 to 518 were taken. All individuals were 
killed in Gilson’s fluid on January 8, twenty-four days after the 
operation. The four kinds of operation were: 
Right fore-leg removed at its base. 
All four legs removed. 
Tail alone removed. 
Tail plus all legs removed. 
SSA Sf 
The data are given in Tables I and II. The lengths are in 
millimeters and the tail length equals the distance from the level 
of the hind legs to the tip of the tail. 
Two kinds of comparisons may be made from the data: 
a ‘The length of the regenerated tail when it alone 1s removed 
may be compared with the same when there is an additional injury 
involving the removal of the four legs. The specific amount 
regenerated" gives the best basis for a comparison. Seven indi- 
viduals in each group are available and are arranged in order of 
their specific amounts in Table 3. Notwithstanding an over- 
lapping in individual cases it is evident that on the whole the 
faster regeneration of the tail takes place when there is an addi- 
tional injury involving all four legs. 
b The regenerated right foreleg when it alone is removed 
may be compared with the same when all four legs or the tail 
plus all four legs are removed. Unfortunately it is not possible 
on account of the various bends in the legs to make an accurate 
measurement. A general side-by-side comparison of the right 
forelegs in the sets with the three different degrees of injury 
did not reveal any differences of sufficient degree to be readily 
14 The specific amount is the regenerated length divided by the removed length. The specific rate 
is the rate per unit of removed length per day. 
