486 Charles Zeleny 
In Series Ia and Ib the removed part was fully regenerated in 
the twenty-four days before the second operation was made. In 
Series Ila, IIb, IIIa, and IIIb between five and six-tenths of the 
length was regenerated in the corresponding period of fifteen 
days. 
On the day when the third operation was made on a half of 
the members of Series Ia and Ib, the first operation at the same 
level was made on the other half. In Series Ila, IIb, Illa and 
IIIb, correspondingly the fourth and first operations were made 
together. 
In Series Ia none of the individuals with a third regeneration 
survived the vicissitudes of the experiment. ‘The data for the other 
five series are given in Tables 3, 4, 5, 6, 7 and 8. Lengths are in 
millimeters. The length of the removed part of the tail was 
obtained by subtracting the length of old tissue in the tail from the 
average length of the uninjured tail in a control series of sala- 
manders. ‘The individuals are arranged in order of length of the 
removed part of the tail. ‘The specific amount equals the amount 
of regeneration per unit of removed tail length. ‘The specific rate 
equals the amount of regeneration per unit of removed tail length 
per day. 
TABLE 3a—AmBLysToMA JEFFERSONIANUM. Series Ib. (Individual Data) 
Approximately four-fifths of tail removed. Regeneration period equals fourteen days 
FIRST REGENERATION THIRD REGENERATION 
Length of removed tail | First regeneration | Length of removed tail| Third regeneration 
} = 
17-4 | 4.2 17.7 4.5 
17.9 ane 19.1 Bas 
19.6 5.0 19.6 | 3-9 
19-7 | (Fol! 19.6 5.0 
20.0 | 3.6 | 
Average......... 18.92 | 4.22 | 19.00 | 4.67 
