NUMBER OF PRE- AND POSTGANGLIONIC NEURONES 365 
vary gland, and blood-vessels of the head from the first five, 
those for the hairs of the face and neck from the first seven. The 
fibers to the middle cervical and stellate ganglia for the accelera- 
tion of the heart arise from the second to the fifth thoracic nerves, 
inclusive. The origin of the fibers terminating in the stellate 
ganglion has been determined as follows: pilomotor fibers from 
the fourth to the ninth thoracic nerve, secretory and vasomotor 
fibers as determined by reactions of the fore-foot from the fourth 
to the ninth thoracic nerves. 
Since there is no cardiac branch from the superior cervical 
ganglion in the eat it is unlikely that the cardiac accelerator 
fibers from the second to the fifth thoracic nerves send any 
branches beyond the middle cervical ganglion. With the ex- 
ception of the accelerator fibers, those from the first three cervi- 
cal nerves appear to run exclusively to the superior cervical 
ganglion. So far as we can tell, then, there are no fibers running 
from the first three cervical nerves which give off collaterals in 
the stellate or the middle cervical ganglion and pass on to end in 
the superior cervical ganglion. 
But the fourth and fifth thoracic nerves send many fibers to 
both the superior cervical and stellate ganglia while the sixth and 
seventh send a few to the superior cervical ganglion. To what 
extent single fibers from these nerves may be connected with 
cells in both of these ganglia is uncertain. But there are certain 
points worth considering in this connection. Most of the func- 
tions controlled through the superior cervical ganglion are highly 
specialized, such as dilation of the pupil, movement of the nictita- 
ting membrane, salivation and lacrimation; and it is not probable 
that preganglionic fibers controlling these functions give off 
collaterals in a ganglion of quite different functions like the 
stellate. On the other hand, it is quite possible that vasomotor 
preganglionic fibers from the fourth and fifth, and pilomotor 
fibers from the fourth to the ninth thoracic nerve send branches 
to both the stellate and superior cervical ganglia. 
The inference to be drawn from this discussion is that while a 
. majority of the fibers ascending to the superior cervical ganglion 
in the truncus sympathicus pass by the other ganglia in their 
