696 
ZOOLOGY: S. R. DETWILER 
Proc. N. a. S. 
of the cord, are capable of adaptive movements led to the inference above 
given, namely, that the defective motility is due to a corresponding in- 
adequacy of central connections and not to any rigid specific relation be- 
tween certain nerves and a given group of muscles. Further, the general 
failure of the motor centres to undergo hyperplastic regulation such as 
occurred in the sensory centres under the conditions of increased func- 
tional demands at the periphery, led to the view that factors other than the 
peripheral requirements must be sought for in the solution of motor read- 
justment. 
In the light of these considerations, the experiments which are herewith 
Explanation of Figures 
(1) Reconstruction model showing the sensory (sr) and motor (mr) roots of the right 
eighth spinal nerve, the spinal ganglion (sg), and the corresponding level of the spinal 
cord (sc) X 180. Nerve not connected with limb. Case TrSc 137. 
(2) Reconstruction model showing the enlarged senso-motor apparatus of the right 
fourth spinal nerve (originally eighth of another animal and transplanted into the limb 
level of the host) X 80. Nerve connected with limb. Case TrSc 137. 
briefly reported were carried out. They consisted in removing that 
portion of the spinal cord from which the normal brachial plexus is derived 
(third, fourth and fifth segmental nerves) and transplanting into the ex- 
cised area a more posterior portion of the spinal cord of another embryo 
that normally gives origin to the seventh, eighth and ninth segment a. 
nerves. These latter nerves, in their normal position, are capable of pro- 
ducing but very limited movements when innervating transplanted 
limbs. 2 The limb rudiments were left intact. 
