610 Sergius Morgulis 
IV RATE OF REGENERATION AFTER SUCCESSIVE OPERATIONS 
Does an organism regenerate faster or slower after it has been 
operated upon for a second or a third time? This seems to be 
an important point in the study of regeneration at the present 
time. Inan earlier publication (Morgulis ’07) I demonstrated that 
in the case of Lumbriculus the rate of regeneration decreases 
approximately geometrically after successive operations from the 
same Pieces of worms, the time element (14 days) remaining the 
same in all three cases. The indices of the rate of regeneration 
from pieces of three different levels were respectively 3.1, 2.6 
and 1.8 after the first operation; 1.8, 1.5 and 1 after the second 
operation; and 0.8, 0.6 and 0.5 after the third operation. 
In a paper, which appeared somewhat later, Zeleny (’08) states 
that in the scyphomedusan Cassiopea xamachana the reverse 1s 
true, the rate of regeneration there being greater after a second. 
operation. 
In some recent experiments (’08) on regeneration in the scarlet- 
runner bean, I performed an experiment for the purpose of deter- 
mining the rate of regeneration after a second operation, and 
there, again, I found that not only is the interval of time inter- 
vening between the operation and the first appearance of regen- 
erating stems greatly prolonged, but also the regenerating stems 
themselves are considerably smaller than those regenerated after 
the first operation, the weight of the regenerated stems and the 
index of transpiration being also most decidedly lower after the 
second operation. 
During last summer (1908) I studied again the rate of regen- 
eration after successive operations in Podarke. ‘The worms were 
divided into two groups. In one group the number of segments 
regenerated during six days was ascertained and the regenerated 
tails then cut off. In the other set the regenerated tails were cut 
off at the end of twelve days from the time of the operation. In 
the first set of worms there had regenerated in six days 4 to 5 
segments (4.4 on the average). These new tails were then severed 
from the body, and the worms were again examined at the close 
of six days. ‘The unfavorable effect of the second operation upon, 
a 
