616 Sergius Morgulis 
urements of the regenerating tails by means of the eye-piece 
micrometer it was found that at the end of sixteen days the tails 
of the fed lot had grown to almost twice the length of the tails 
of the control worms, which had been deprived of food. 
Should we, now, compare the rates of regeneration from the 
three different levels in worms that were fed and in those that 
were not (compare Fig. 6), we shall not fail to be impressed with 
the fact that in both cases the rates of regeneration from the 
different levels form a descending series; but what is still more 
interesting and important is that in well-fed and in starved ani- 
mals, 1. e., when there is a higher or a lower rate of regeneration, 
the ratios between the rates of regeneration from different levels 
remain practically the same. 
The problem of the relation between food-supply and the rate 
of regeneration from different levels was taken up by certain 
investigators with special reference to Zeleny’s tentative hypothesis, 
viz: that the differences in the rates of regeneration of arms in 
the brittle-star Ophioglypha lacertosa might perhaps be due to 
the different amounts of food available for the regenerating part 
in animals with one, two, three or four arms cut off. It has 
since been shown, however, by Morgan (’06) and by myself (’07) 
that even in starved animals there is a difference in the rates of 
regeneration from various levels, thus rendering food-supply at 
least a secondary factor, if indeed it has any influence in deter- 
mining the rates of regeneration from different levels. 
The evidence previously adduced may be considered as merely 
negative. ‘hat which the present experiments offer is, I believe, 
of a more positive kind. Though food is a factor determining 
to a certain extent the rate of regeneration of an organism, it is 
not the factor which determines the difference in rates of regen- 
eration from different levels. JI desire, therefore, to call special 
attention to this distinction in the influence which is attributed 
to the factor of food in regenerative processes. 
