446 S. W. RANSON AND P. R. BILLINGSLEY 
Above the level of the eleventh ganglion there was some evi- 
dence of degeneration, and this could be followed up as far as the 
tenth. The evidence of an ascending degeneration was, how- 
ever, by no means as clear as that for a descending degeneration. 
The gray rami of the eleventh, twelfth, and thirteenth thoracic 
nerves were normal, containing a few fine myelinated fibers. 
No axon stain was made. ‘The white ramus of the tenth nerve 
was not well stained, that of the eleventh nerve has already been 
described and figured. The twelfth white ramus contained a 
fair number of medium and small-sized fibers, but no large ones. 
Most of the normal fibers in the thirteenth white ramus were 
also of medium and small size. It is clear that in these rami 
of this cat the afferent fibers were for the most part of medium 
and small size. We regard the paucity of large fibers as some- 
what atypical. 
The point which stands out most clearly as a result of this 
experiment is that the majority of the fibers of the tenth and 
eleventh white rami turn downward in the trunk, forming a well- 
defined fascicle near its surface which can be traced in the trunk 
beyond the origin of. the great splanchnic nerve. At least in the 
upper part of this course the fibers from the two rami remain 
separate, those from the eleventh lying superficial to those of the 
tenth. This lamination of the fibers in the trunk in flattened 
bundles, corresponding to the white rami from which they come, 
explains why it is easy to follow these fibers by dissection through 
the trunk to the splanchnic nerve, as is claimed by Langley 
(00). 
The degeneration of the preganglionic fibers in the lower 
thoracic white rami enables us to isolate the myelinated sensory 
fibers and to see that these include fibers of all sizes. These 
can be seen not only in the rami themselves, but also in the 
degenerated fascicles representing these rami in the trunk. 
Cat XII. The sympathetic trunk was cut on the left side at 
the level of the ninth internodal segment and the roots of the left 
ninth, tenth, eleventh, twelfth, and thirteenth thoracic and first 
lumbar nerves were cut proximal to the spinal ganglia, as shown 
in figure 1. The cat was killed thirteen days after the operation. 
