ANALYSIS OF THE SYMPATHETIC TRUNK 443 
myelin globules, though a very few of them retained a normal 
appearance. There was very little degeneration of the large 
fibers, and, since the fibers present at this pot must nearly all 
have been cut away from their cells of origin, we must interpret 
this result as showing that sufficient time had not elapsed for 
the degeneratiou of the large fibers. It has been shown by Van 
Gehuchten and Molhant (’10) that the speed of degeneration in 
myelinated fibers is inversely proportional to their size. In 
parts of the crescentic field the scattered fine myelinated fibers 
were normal, in other parts of this same field they were all 
degenerated. 
A cross-section of the trunk below the tenth ganglion showed 
most of the scattered fine myelinated fibers in the crescentic 
field to be normal in appearance, indicating that few of them took 
origin above the cut. The oval field had the same appearance 
as in the section described above. The tenth white ramus could 
be seen in longitudinal section as it entered the trunk. The 
majority of its fine myelinated fibers had their myelin broken up 
into globules, giving them a beaded appearance. Its large 
fibers and a few of the small ones were normal. 
Sections of the greater and lesser splanchnic nerves showed 
that most of the fine myelinated fibers were degenerated, while 
the large fibers were all or nearly all normal. These results were 
confirmed by a study of teased preparations of the twelfth inter- 
nodal segment of the trunk and the greater splanchnic nerve. 
In these teased preparations it was possible to see that a few 
large fibers were also in the early stages of degeneration. 
Cat VII, killed thirty-three days after section of the roots of 
the left tenth, eleventh, twelfth, and thirteenth thoracic and first 
lumbar nerves proximal to the spinal ganglia as indicated in 
figure 2. 
Sections of the trunk below the entrance of the tenth white 
ramus showed a circumscribed area of degeneration at the surface 
of the trunk. In this area there were two large and a consider- 
able number of small normal myelinated fibers. This degenerated 
area was taken to represent the tenth white ramus, although 
enough sections were lost from the series at this level to prevent 
our tracing that ramus directly into the degenerated area. 
