* 
686 A. Ff. Goldfarb 
without interfering with the innervation. ‘The operation was per- 
formed in several ways so as to offset the possibility of the result 
being due to faulty technique. In every animal so operated, regen- 
eration of the tail was absolutely stopped, at least during the 204 
days of observation. 
‘That the sensory ganglia exercised no stimulating or retarding 
influence was readily proved first, by completely destroying the 
sensory ganglia of the plexus nerves of the leg as well as the ganglia 
of the tail. ‘The organs were invariably replaced. Regeneration 
could not be prevented. Secondly, by leaving these ganglia intact 
but preventing regeneration of the organ by other means. Under 
these circumstances the ganglia were unable to induce regenera- 
tion. | 
From these experiments it is clear that we no longer have any 
justification for referring to “morphogenic” or “trophic” or_ 
“formative” stimuli exerted by the nervous tissues in the regenera- 
tion of this adult animal, any more than the use of such expressions 
with reference to bony or cartilaginous tissues. Inother words the 
adult D. viridescens replaces its tail and hind limbs without the 
aid of a nervous stimuli, either motor or sensory. 
REGENERATION OF THE TAIL OF THE FROG TADPOLE IN RELA- 
TION TO THE NERVE CORD AND NOTOCHORD 
Many experiments have been made upon amphibian larve for 
the purpose of ascertaining whether the central nerve system 
exercises a morphogenetic influence in development and regenera- 
tion. With few exceptions these experiments were made upon 
tadpoles in their earliest stages of development. Schaper, Rubin, 
Barfurth, Goldstein, Harrison, Braus and other investigators were 
led to conclude that development and regeneration of embryos 
take place independently of a central nerve system. Morgan and 
Davis ’o02, used older tadpoles. When they removed the nerve 
cord from the tail, regeneration proceeded as in normal individuals, 
but when a piece of the notochord was removed regeneraton was 
effectually prevented. In other words the nerve cord was incom- 
petent alone to induce the formation of a new tail. It is condi- 
