THE STRUCTURE OF THE SPINAL GANGLIA 165 
activity in the neurone. Cajal (07) accepts this interpretation 
and Bielschowsky (’08) extends it to the fenestrated cells and to 
the cells whose axons have plexuses intercalated in their course. 
On this hypothesis one would expect to see an increase in the 
number of such cells after the division of the associated nerve. 
With this in mind the left sciatic nerve was cut in four dogs and 
after one month the associated spinal ganglia were prepared by 
the pyridine silver technique. The results of these experiments 
were entirely negative. There was no increase in the number of 
fine fibers ending in end bulbs nor were any other of the peculiar 
cell types seen in the normal ganglia increased in number. 
Since the division of the axons might be expected to be as efficient 
as any stimulus in producing regenerative changes in the neurone, 
these experiments, so far as they go, speak against the interpre- 
tation of these new cell types as the expression of a slow regen- 
eration constantly going on in the normal ganglia. Other 
experiments are in progress with the purpose of making a more 
complete test of the hypothesis of Nageotte. 
The axons of the small cells 
In concluding his section on the cerebro-spinal ganglia in 
‘Plasma und Zelle,’ Heidenhain (’11) says: 
Es wirde gewiss fiir die Physiologie von grosser Bedeutung sein 
wenn wir behaupten kénnten, das wir mit der Anatomie der cerebrospin- 
alen Ganglien im reinen sind. Dies ist jedoch nicht der Fall. Erstlich 
ist der Ursprung der erwaihnten afferenten sympathischen Fasern leider 
nicht néher bekannt .. . Und zweitens befindet sich nach 
den Zihlungen von Gaule und Lewin, ebenso von Biihler in den Gan- 
glien eine ausserordentliche Ueberzahl von Zellen deren Fortsitze wir 
noch nicht kennen. 
It is with this second problem that we wish now to deal. The 
numerical excess of spinal ganglion cells over medullated afferent 
fibers is well established as table 1 shows, although in most cases 
it is not so great as that found by Gaule and Lewin in the 32d 
spinal nerve of the rabbit. 
Hatai (02) by a separate enumeration of the large and small 
cells of the (tv C, rv T and 11 L) spinal ganglia of the white rat, 
