Influence of the Nervous System Tus 
sure the eye spot of operated arms appeared several days later. 
The development of new ambulacral feet and the skeleton of the 
new arm took place in both the control and nerveless arms. ‘The 
rate was about the same although some of the operated ones 
lagged behind. Further development was approximately the same 
in both. 
REGENERATION IN PLANARIA IN RELATION TO THE NERVOUS 
SYSTEM 
The investigations of T. H. Morgan, Child, Lillie, Stevens, 
L. V. Morgan, Shultze and others have shown that different species 
and genera of planaria differ radically in the power to replace lost 
parts. To cite but a few examples. Planaria maculata is able 
to regenerate a whole worm from a piece taken from almost any 
level; Dendroccelum lacteum like P. maculata can regenerate 
posteriorly at all levels but anterior restoratidn takes place only in 
that third of the animal nearest the head; in Leptoplana anterior 
regeneration is still further restricted to the region immediately 
back of the cephalic ganglia. “These facts suggested some connec- 
tion between the reduced power of regeneration and the increased 
cephalizat on of the animal. Lillie advocated this view after an 
examination of the nervous systems in three different planarians. 
L. V. Morgan and Bardeen believed that whenever the anterior 
and of the nerve cord was exposed a head regenerated at that place. 
Child made the interesting discovery that the formation of a head 
could be prevented by removal of the “brain,” and that the extent 
of the regeneration was in proportion to the amount so removed. 
More recently Child has inclined to the view that “the relation 
between the nervous systemand morphogenesis is of a very proble- 
matic character, though the existence of a relation of some sort can 
scarcely be denied in many cases. This relation may be either 
direct or indirect.”” He states his position as follows: “A change 
in kind or degree of functional activity is of course accompanied 
by changes in the complex of functional conditions to which the 
partis subjected. If these conditions play any part in the morpho- 
genesis or form maintenance a relation between the nervous system 
