526 Charles Zeleny 
after the operation. The necessary precautions employed are 
given in the general outline of the sources of error (pp. 514 to 
to 518). Ineachgroup there is an individual with the tail alone 
cut off, one with the tail plus the right fore-leg and one with the 
tail plus both fore-legs removed. The lengths of the regenerated 
tails and other measurements are given in Table 4. With the 
exception of one individual (No. 96q) it is seen that the per cent 
TABLE 4 
Amblystoma opacum 
ay = Tail alone removed 
T+r. F. L. = Tail plus right fore-leg removed 
F 
T+b. F. L. = Tail plus both fore-legs removed 
paay rte alee | [ = 
| | TOTAL | LENGTH OF | LENGTH OF | PER CENT 
CATALOGUE PARTS : | | | 
ORIGINAL | REMOVED | REGEN- REGENER- 
NUMBER REMOVED | | | 
BODY LENGTH PART OF TAIL) ERATED TAIL| ATED. 
INMMS. | INMMS. | IN MMS. | 
| | | 
967 |, Diaz | 6.2 2.6 | 42 
Group one.... 4| 968 | T+r.F. 1. 22.4 ? | Bal 5o+ 
969 pedbi sel ee 23-9 | 5-9 | 2.0 | 34 
| | | 
| +974 -T 20.1 | OF | 3.7, | 62 
Group two.... 975 Villy Seen Noy bg 20.4 | 5.8 | 3.8 66 
| 976 |T +b. 1d I De 20.0 | Gail | eG] | 73 
| | 
(| 981 fae 22eQ 6. a0 45 
Group three... 982 ([T+rF.L. 21.9 6.0 | ao | 52 
983 (De ba Be 20.9 5 3.6 heen) 
| | | 
[ 988 ae Ppa) 6.6 Doo | ag 
Group four.... 989 /T+r.F.L 22.0 6.6 [hi Maven |- | 36 
| 9go fab Se toe Jaa If DET 
535° “4s, eee 44 
of the removed length of the tail regenerated is least in the indi- 
viduals with the tail alone removed and increases with increase 
in additional injury. 
The special objection to the results of this experiment applies 
equally well to the following observations on Amblystoma. ‘These 
observations were made as parts of a larger experiment and in 
all only a few individuals are available for comparison. ‘The 
