Influence of the Nervous System 707 
with their ax‘s at right angles to the axis of the cord. “In the 7th 
segment these have divided repeatedly to form a mass of smaller cells, 
with their axes at a sharp angle to the axis of the cord. In the 
anterior end of segment 7 and in the 6th, there is a steady diminu- 
tion in the width of the cord and an absence of large ganglion cells. 
In the 5th segment the cord increases in diameter, in the total num- 
ber of nerve cells and in the number of larger nerve cells. “These 
are not well shown in Fig. 21 nor is the greater width of the cord in 
the 4th segment shown in this figure. It appears highly probable 
that the more extensive proliferation of nerve cells and their fibers 
from the ectoderm posteriorly has met the forward grow:h of the 
cord near the posterior end of segment 5. 
IN Gye beet ratte ere eteehs ayers) ei efaieisie1=: vie ei!elela ce ein e1s/s/s\01 /a)= 91 mn 1.54 1.48 27) 
| 
reg. cord | reg. cord reg. cord 
ole 5 6 
Greatest width of cord in each segment................ | 3 2 5 
| 3 | 5 3 
old cord | old cord old cord 
Greatest width of cord in each segment...............- f | ne | ay de 
| 10 13 
\ i fe) 
No. 1.61 and 1.44 are worth mentioning. Only two and three 
ganglia respectively had been removed and subsequent regenera- 
tion of the cord took place in such a manner that the greatest width 
in each segment, beginning at the anterior end was 8, 6, 11, 12, 13, 
iqy cies units and 9; 54, 10, 10; 12; 12,:etc., units respectively. 
In other words the width decreases from the commissures poste- 
riorly. The ganglionic masses seem also to be more highly devel- 
oped at the anterior segment, less so-in the next segment. ‘This 
evidence seems to strengthen the conclusion that from the anterior 
end, the new cord had regenerated posteriorly as far as the grow- 
ing end of the posterior cord. 
The growth of the new cord posteriorly may be relatively faster 
than the forward growth from the broken end of the cord. At 
the anterior end, the nerve cord resembles more and more closely 
the typical cord, both in dimensions and differentiation of the 
