Physiology of Regeneration 613 
to occasion regeneration,’’? or those of Morgan (’o1I-’o2) in which 
he showed that planarians in the last stages of starvation will still 
draw upon their emaciated bodies to make good a portion removed 
by an operation. 
These are, indeed, very striking cases; nevertheless it is going 
too far to maintain on the basis of these data that food usually 
has no effect whatever. 
In the present chapter we are concerned with the food-supply 
not as a factor in regeneration, but rather as a possible factor in 
determining the rate of regeneration. The following data have 
been derived from experiments which were conducted during the 
summer of 1907 and repeated in 1908. 
A number of worms were separated into three groups. In the 
first group (A,) the total number of segments removed was 171 
(or 21.4 on an average), and that of the segments left in the pieces 
experimented on was 135 (an average of 16.9). [he same num- 
bers in the second group (B,) were respectively 127 and 180 (or 
on the average 14.1 and 20 segments respectively). In the third 
group (C,) these numbers were respectively 83 and 249 (an aver- 
age of 9.2 and 27.7). 
This experiment was carried out as has been stated in 1907, 
and the data presented in Table I (p. 599) are to serve as the 
control. - I may also say that the worms used in the experiment 
and in the control belonged to the same lot, all having been col- 
lected from one place and at the same time. 
The average numbers of segments removed and of those present 
in the pieces used in the experiment (A,, B,, C,) are almost iden- 
tical with the corresponding numbers of the control (A, B, C).‘ 
The worms of the three groups were kept in separate dishes 
and were provided with the sea-weed, on which they are always 
found, taken from the Woods Holl “Eel-pond.” Thus, unlike 
the worms of the control they were constantly provided with food. 
3 It has, however, been shown recently by Kupfer (’07) that regeneration in plants is dependent 
upon an adequate supply of food; that in plants from which the reserve food has been exhausted 
no regeneration takes place and that also in white shoots of several species the same holds true. 
4It will be recalled that the worms of this experiment were kept in dishes with pure sea-water and 
were deprived of any food. 
