Influence of the Nervous System 677 
cord was destroyed instead of 2$ mm.; (2) the time was greater, 
namely, 78 days; (3) there was greater injury to the neural arch and 
a corresponding greater proliferation of the cartilage. 
No. 1.4. The needle destroyed but 2 mm. of the cord. For the 
next millimeter, the cord had been removed on one side only. 
The subsequent changes were the same as those already described. 
Four millimeters of the tail had regenerated in 66. days. 
No. 1.9. Destroyed 34 mm. of the cord. After 124 days the 
new tail was not quite 3mm. long. Degeneration of the fibers of 
the cord had extended as far as 8 mm. from the amputated level. 
No medullated fibers were present in the distal 11 mm. of the 
tail. 
Fig. 7 Cross-section. Later stage of regenerated nerve cord, showing multiplication of cells and 
their migration laterally to constitute the ganglia, and the layer of embryonic fibers. Figs. 5 to 7 incl. 
same magnification. 
No. 1.3. Destroyed 5 mm. ofthe cord. Regenerated tail6 mm. 
Time, 142 days. 
No. 1.8. Destroyed 4 mm. of the cord. Regenerated tail 
64 mm. ‘Time, 170 days. It was rather surprising to find that 
even as late as 170 days after the operation there were no medul- 
lated fibers near the amputated end nor in the 34 mm. anterior to 
it. This of course is not surprising when taken in connection with 
what was learned concerning the slow rate of regeneration of the 
cord and fibers of the leg. Further progress consisted in increased 
length of the tail and increased differentiation of the different 
tissues. 
