Influence of the Nervous System 667 
greater part of the neural arch has likewise been destroyed. The 
latter however has been partly replaced by an irregular mass of 
cartilage, shaded lighter in the figure. On the right side the 
ganglion and its nerves and its bony compartment are intact. 
Unfortunately in all cases where at least the three plexus ganglia 
were wholly destroyed the animals had been killed before a sufh- 
cient time had elapsed to determine whether regeneration could 
take place. All that the evidence warrants is the conclusion that 
Fig. 4 Cross-section through region of pelvic plexus. Shows complete removal of the nerve cord 
and left dorsal ganglion. Cartilage has proliferated to partly fill space formerly occupied by left half 
of vertebra. Magnified same as Fig. 2. A, remains of neural arch; Ca, proliferated cartilage; G, 
sensory ganglion; G’, space formerly occupied by ganglion; N, space previously occupied by vertebral 
canal. 
the removal of the major part of the sensory stimult, with or without 
the destruction of the motor stimuli, does not inhibit.regeneration 
of the legs. Later, however, it will be conclusively demonstrated 
that in the tail of this animal dorsal or sensory ganglia do not pro- 
vide the stimulus to morphogenesis. 
Nerves Removed from Limb 
Very little need be said concerning this series. The nerves of 
the thigh were exposed, and a rather large piece removed from 
. 
