596 Sergius Morgults 
factors involved in bringing about a certain reaction, the signifi- 
cance of each may be judged by the modification of the reaction 
occasioned by either changing or completely eliminating one of 
these factors. “This method could not be resorted to, to decide 
the question whether the whole injured organism or the injured 
surface alone is concerned with proliferation and growth of tissue 
for the reason that we can neither eliminate the organism and 
retain the cut surface, nor retain the organism without the cut 
surface. A definite solution of this problem is, nevertheless, 
quite important for the proper understanding of the process of 
regeneration. 
We might, of course, point to the fact that regeneration 1s 
accompanied by changes in the equilibrium of the injured animal 
form, as was brought out by Przibram (’07), and that the regen- 
eration from the cut surface is sometimes concomitant with phe- 
nomena of reduction or compensation affecting non-injured and 
distant parts of the body (Kammerer ’07). 
It is true that the histogenetic phenomena are specially pro- 
nounced near the cut end, but, as was shown in the regenerating 
hydra—*‘new cells are not found at the cut surface alone. 
Divisions were found to occur as well at the sides as at the ends 
of the regenerating piece.” (Rowley, p. 582.) 
Furthermore, if regeneration is a function of the organism, it 
should be open to modifications contingent upon changing the 
physiological condition of the organism; and a part of the present 
paper deals with this problem. Additional evidence, derived 
from the study of the regeneration in Lumbriculus, will be pre- 
sented in the second paper of this series. 
Acknowledging the pertinence of objections that may be raised 
and admitting the great difficulty of establishing by circuitous 
ways beyond further dispute the view which was put forth at 
the beginning, it seems none the less a cogent argument that an 
accumulation of facts which indirectly bear out this hypothesis 
may swing the balance strongly in favor of the view, which from 
the physiological standpoint is the more probable. 
