Influence of the Nervous System 661 
to permit them to move slightly. It took 117 days for all these 
changes to take place. In the meantime the new leg had grown 
24 mm. long and had differentiated all the toes. 
No. 1.13. Four days after the operation both limbs showed 
indefinite movements. ‘The sole of the foot was upturned for a 
long period even after the leg was able to move considerably. ihe 
animal was preserved 139 days after the operation. Internally 
the parts were very much like those already described in 1.25. 
The cord had been injured but not totally removed from the region 
of the plexus. Of especial interest are the nerves of the leg. 
Quite different from those in the totally paralyzed legs of the same 
stage, the motor as well as the sensory nerves have regenerated and 
have grown to and beyond the amputated end. In point of fact 
these new fibers cannot he distinguished from normal ones both as 
to structure and staining power. ‘The opposite limb amputated 
39 days before preservation stands in sharp contrast, for typical 
Wallerian degeneration has set in near the cut end. ‘The left 
hind limb had grown 5 mm. and was quite normal, the right had 
only grown 1? mm. 
No. 14.1. The legs began to move after a lapse of 159 days, the 
left with greater difficulty than the right. The animal was pre- 
served 177 days after the operation. ‘The cord had completed itself 
from injured remnants left after the operation. Such regulation 
extended from nerve II posteriorly. Just as in the preceding 
many nerve fibers, mostly sensory, have regenerated to and beyond 
the amputated end. ‘The new part of the leg was 34 mm. long, but 
quite normal with 5 distinct and typically formed toes. 
Control Series 
We may now briefly consider the nature of the changes that take 
place after amputation of the hind limbs and without injury to the 
cord, and compare them with the changes after injury or removal 
of the cord. 
The first animal to be mentioned was preserved 35 days after 
amputation (No. 10.4). The nerve fibers show near the cut end 
only the typical degeneration already described. ‘The bone pro- 
liferated a cap of cartilage and between it and the skin there was a 
mass of “embryonic” tissue. ‘The sections are not different from 
