442 S. W. RANSON AND P, R. BILLINGSLEY 
preganglionic efferent fibers coming from the spinal cord (page 
421). The white rami of these three nerves showed marked 
changes. Most of the small myelinated fibers were undergoing 
degeneration, but there were a few which in cross-section appeared 
as sharply contoured black rings. These were apparently normal 
as were also all of the large myelinated fibers. In the trunk 
Fig. 1 Diagram of the thoracic sympathetic trunk with the corresponding 
spinal nerves and rami communicantes to illustrate lesions produced in cats IX 
and XII. The course of the degenerated fibers is indicated in black. N.S.M. = 
N. splanchnicus major. 
Fig. 2 Diagram of the thoracic sympathetic trunk with the corresponding 
spinal nerves and rami communicantes to illustrate the lesions produced in cat 
VII. The course of the degenerated fibers is indicated in black. N.S.M. = N. 
splanchnicus major. 
above the level of the tenth ganglion, i.e., between the lesion 
and the next lower ganglion, the oval field described in the 
preceding paper (fig. 5, page 426), was largely degenerated. 
Nearly all of the fine myelinated fibers were represented by 
