Influence of the Nervous System 693 
nereis is not unlike the earthworm, it is highly pro>able that the 
destruction of the nerve cord from the end, 1, 2 or 3 segments 
did not suffice to remove all motor stimuli from the amputated end. 
The point I wish to emphasize is that in order to ascertain whether 
the nerve cord is essential, 1. e., whether it is necessary in morpho- 
genesis, it becomes necessary to completely remove the cord from 
more than three segments next to the cut end. This Nusbaum 
appears not to have done. His proof is not complete until it can 
be shown that the removal of the cord for more than 3 seg’ments 
either greatly retards regeneration until the fibers will have reached 
the end, or totally inhibits the growth of a new tail. 
My experiments on the earthworm were practically completed 
when Nusbaum’s paper was published. 
I found as Morgan had found that there was a very large mortal- 
ity following the operations. Furthermore, believing that the 
removal of tissues other than the nerve cord might introduce dis- 
turbing factors, I was led to devise some other method of removing 
not only the nerve cord but the bases of the lateral branches as 
well. ‘The anterior 3,40r 5 segments were amputated. ‘Thebrain 
and circumcesophageal commissures were removed with the 
anterior piece. Fine forceps were introduced into the posterior 
piece in such a manner that the points were close to the cord. At 
the desired depth the cord was seized and pulled out. It was 
rather surprising to find how readily the cord and considerable 
pieces of the lateral nerves could be removed. The piece was 
examined under the microscope and the number of ganglia counted. 
Fig. 14 is an example of a nerve cord that was extracted in this 
way. Sometimes the nephridia were extracted instead, but a 
glance through the microscope revealed the error and the particular 
worm was discarded. In every worm to be hereafter mentioned, 
Table 4, the “brain” and circumcesophageal commissure, and the 
whole of the cord for a given number of segments, together with 
the basal parts of their lateral nerves were removed. ‘The ampu- 
tated end of such worms was therefore intact except for the absence 
of the cord in from 2 to II anterior segments. 
Similar operations were made at the posterior ends of pieces cut 
near the middle or posterior levels of the worm. But the injured 
