Influence of the Nervous System 719 
brates, for in other forms as well, differing widely in organization 
such as the earthworm, the starfish and the planarian, the same 
result was obtained. 
The earthworm affords a clear case. Study of serial sections 
established beyond all doubt that the whole of the ventral nerve 
cord and the cellular part of the lateral nerves had been removed 
from the region comprising from 2 to 9 segments nearest the ampu- 
tated anterior end. Out of 200 operated worms approximately 
one-half regenerated a functional and typical head. On exami- 
nation it was found that a new nerve cord had regenerated between 
the old cord and the new “brain;’ and it appeared that this regener- 
ated cord grew rapidly from the old cord anteriorly and partly 
from the anterior end in a posterior direction. In three worms at 
least, the regeneration of the cord had proceeded so slowly that 
the “brain” of the regenerated head and the anterior end of the 
old cord was separated by a space of three to eight segments, 
entirely devoid of any trace of the nerve cord or of connecting 
motor fibers. ‘This distance is far too great to permit any sec- 
ondary nerve connections. We are thus led to conclude that the 
head of the earthworm may regenerate entirely independently 
of the nerve cord. 
On account of the diffuse character of the nervous system in the 
starfish and in the planarian, the absolute removal of all nerve cells 
from the amputated region is rendered next to impossible. The 
experimental evidence, however, showed that even after removal 
of the principal nerve tracts of both starfish and planarian, regen- 
eration takes place quite readily. 
These results are in full harmony with the recent investigations 
of Schaper, Rubin, Barfurth, Harrison and others, viz: that larval 
development is independent of a nervous control. ‘They are also 
in entire accord with the more recent results according to which 
functions formerly attributed to the central nervous system are now 
relegated to other agencies. 
We reach, therefore, the general conclusion that regeneration 
of typical organs in adult as well as in larval animals can take place 
in the entire and permanent absence of any influences exerted by 
or through the central nervous system. 
Zodlogical Laboratory, 
Columbia University. 
