Vol.. 6, 1920 
ZOOLOGY: S. R. DETWILER 
97 
tween the nervous and non-nervous cells. Nevertheless, the results ob- 
tained from counting approximately eighty thousand cells, in addition 
to a comparative study of the size of the ventral roots, indicated that a 
hyperplasia of the motor centers had not taken place. 
-{ The evidence, however, of a hyperplasia of the sensory centers was very 
specific. In case AS426 the right anterior limb, which was transplanted 
the distance of four segments posterior to the normal limb level, was in- 
nervated by the fifth, sixth and seventh segments of the cord — the normal 
Fig. 1. Drawing of a reconstruction model showing the third and fourth 
left spinal ganglia (connected with the normal intact limb) . X 50 
Fig. 2. Drawing of a reconstruction model of the third and fourth spinal 
ganglia showing great reduction in size as a result of excision of the limb. X 50 
intact left limb receiving its innervation from the third, fourth and fifth 
segments.^ The right sixth and seventh spinal ganglia (connected with 
the transplanted limb) were found to be considerably larger than the 
corresponding ganglia on the left side (not connected with a limb), the 
comparative sizes being illustrated in figures 3 and 4. The results of 
counting the sensory nerve cells in the ganglia on the two sides showed 
clearly that the hypertrophy was due to a marked hyperplasia of the cells. 
The removal of the limb from its normal position, likewise, resulted in 
a marked reduction in the sizes of the third and fourth ganglia which 
normally supply it with sensory nerves (figs. 1 and 2). 
