Analysis of Rate of Regeneration 413 
It is to be noted that, although the length of the four intervals 
of change in rate of regeneration represented by the data, vary 
somewhat in the four experiments recorded, and although the 
rate is subject to variations occasioned by such factors as food, 
temperature, age and condition of the water; the four kinds of rate 
changes are plainly evident in each experiment, they follow each 
other in the same order, and each interval of change has the 
same relative duration in each experiment. ‘Thus the first interval 
of low rate is short, it is followed by a longer interval of rapidly 
increasing rate. ‘The third interval is not so long as the second, 
but longer than the first, it always has a rapidly decreasing rate. 
The fourth interval is longer than all of the others and has a 
gradually decreasing rate. 
VOLUME 
It was thought very desirable to find the rates at which volume 
was added to the regenerating tail. Several methods were tried 
with indifferent success. When the tail was weighed in air evap- 
oration caused the weight to change faster-than the scales could 
be read. ‘The weighing of the tails in water was entirely inaccu- 
rate because the tail was too frail to be dried before it was weighed, 
and in the younger stages of regeneration the water adhering to 
it weighed as much as the tail. An examination of Table VI 
TABLE VI 
TEs ERAS a0 eying A re | 3 | 5 | 7 | 10 | 2. ||) ire | 17 
| 0.29 | 0.55 | 1.04 | 4.40 | 2.94 | 3.06 | 2.78 
| | | | 
Volumes of tails ateach stageincu.mm.......... 0.38 0.88 2.82 | 4.87 | 5.23 | 3.70 | 6.73 
(| | 2.84 | 4.36 | 4.22 | 
will make this statement more comprehensible. The results given 
in this table were obtained in the following way. The tails pre- 
pared for the histological study (Experiment IV) were all care- 
fully dehydrated at the same time, and then imbedded in paraffin 
likewise at the same time to insure similarity in the treatment 
with each reagent. Each tail was mounted in serial sections of 
