50 M. L. Shorey 
said that the smaller the muscle, the greater is the proportionate 
size of the nerve. 
4. Muscle fibers in abnormal positions without any apparent 
attachment to the skeleton, always receive innervation. 
5 Except in the early stages of development no nerve fibers 
are ever found wandering free in the mesenchyme, but they follow 
a definite path leading to a muscle or other end organ. 
6 Decrease in the number of the peripheral motor nerve fibers 
is always accompanied by a decrease in the size of the ventral 
root. In some cases, an extensive destruction of musculature 
leads to the union of two ventral roots, and a consequent decrease 
in the number of nerve trunks. 
7 Defects in the size of the motor nerves are always accom- 
panied by a corresponding defect in the ventral horn of the spinal 
cord, but in no case is the latter entirely lacking, even when the 
musculature of the somite in which it is located has been completely 
extirpated. 
8 In some specimens the distance from the central canal 
of the spinal cord to the inner edge of the ventral horn is greater 
on the operated than on the unoperated side, and the line of demar- 
cation between the ventral horn and the surrounding cells is less 
definite. 
g [Extirpation of sensory areas has the same effect on the 
spinal ganglia and dorsal roots that the extirpation of motor organs 
has on the ventral roots and motor nucleus. In case the ventral 
roots are united the ganglia and sensory roots are also united. 
10 A decrease in the size of the ganglia is accompanied by a 
decrease in the size of the dorsal horn, but this effect 1s not observ- 
able until a somewhat later period. 
11 In regions where the ganglia and nerve roots of two succes- 
sive somites unite, the entire half of the spinal cord is slightly 
decreased in size, but there is no definitely localized area of loss. 
12 Effect on the spinal cord is mostly confined to the region 
from which the nerves innervating the extirpated parts arise, but 
slight defects both anterior and posterior to this level are usually 
observable. 
13 The first defect in the nervous system is demonstrable about 
