THE CERVICAL SYMPATHETIC TRUNK 319 
Waller and Budge showed long ago that the sympathetic trunk 
after section in the neck degenerated toward the superior cervical 
ganglion. Their results have been confirmed by Langley (’96, 
700). This author used the rather unsatisfactory method of 
examining the degenerated nerve in teased preparations stained 
with osmic acid. He found, however, just as we, in sections 
stained with osmic acid, that some fine branches of the superior 
cervical ganglion may accompany the nerve for a certain distance. 
He also found that occasionally a branch from the vagus might 
run to the superior cervical ganglion and accompany the nerve 
for a way. This may have been the depressor nerve (p. 374). 
After the sympathetic trunk below the stellate ganglion and the 
rami communicantes to the first and second thoracic nerves were 
cut and time allowed for degeneration, he found no sound myelin- 
ated fibers in the cervical portion of the nerve, aside from the 
bundles just mentioned which may happen to be included in the 
same sheath with it. He concluded that no myelinated fibers 
run from ganglion to ganglion through this nerve and none join it 
from the cervical rami communicantes. 
We have pyridine silver preparations of the degenerated nerve 
in both cat and dog. In each case the structure is the same. 
Take, for example, Cat XII which was killed fifteen days after 
the division of the sympathetic trunk in the neck. In that part 
of the nerve just below the superior cervical ganglion the sections 
stained with silver showed two fascicles of fine undegenerated 
axons mostly unmyelinated at the periphery of the trunk. Fol- 
lowing the sections caudally through the series, one of these 
fascicles can be seen to leave the trunk, but the other remains 
with it as far as our series goes, although it would no doubt 
separate off a little farther down. 
Aside from these two peripheral fascicles, which, properly 
speaking, do not belong to the nerve, almost all of the axons 
have degenerated. Here and there throughout the section there 
seems to be an isolated unmyelinated axon of normal appearance. 
These normal unmyelinated fibers are not numerous. In fact, 
since we have never seen such isolated unmyelinated axons 
