706 | A. F. Goldfarb 
like those described in the first section. But instead of ending 
blindly as the latter do, they swerve dorsally, near the amputated 
end, become filled with nerve cells to the almost complete oblitera- 
tion of the fibrous layer, and end in the cerebral ganglia. 
In No. 1.59 for example, the greatest width of the cord measured 
in the middle of each segment is as follows: 
SEGMENT Unirts® 
sth 5 
6th 5 
7th 5 
regenerated cord. 
8th 5 
gth 5 
roth 5 
zee oo \ old cord. 
12th II 
etc. 
At this last level the cord widens a trifle and merges into the “‘ brain.” — 
No. 1.31 is practically the same. 
SEGMENT Units 
4th 5 
sth 
éth regenerated cord. 
7th 5 
an + \ old cord. 
gth oe 
In the following three worms posterior growth seems to have 
taken place with great vigor, so that the nerve cord immediately 
behind the cerebral ganglia, and ventral to it, is crowded with 
nerve cells in all stages of different ation. The cord tapers about 
midway between the old cord and the new “brain,” widening 
towards the brain on the one hand and towards the old cord on 
the other. 
In 1.54 the cerebral ganglia have not yet separated from the 
ectoderm from which they take their origin. In 1.48 and 1.27 the 
separation is completed. Fig. 21 is a longitudinal section of 1.27 
showing the ventral and anterior end of the worm. In the 8th 
segment the cord is quite typical containing large ganglion cells 
8 Measured with eye-piece micrometer, with the same magnification in each case. These relative 
measurements suffice for the present purpose. 
