SACRAL SYMPATHETIC TRUNK OF CAT’ 101 
of the small fibers have completely degenerated, and that only 
an insignificant number of the smallest medullated fibers found 
in the trunk remain. The few small medullated fibers which 
do remain appear to be practically limited to the gray rami and 
the lower poles of the ganglia. In only one instance (the second 
coccygeal internode) were any of these fibers found in the inter- 
nodal segment distal to its related gray ramus. 
In a second specimen the operation was modified to include 
only the spinal nerve roots on the right side in addition to intra- 
abdominal division of both sympathetic trunks as previously 
described. Both trunks were stained, and in the right the results 
are identical to those described above, in the left, to the results 
obtained in the singly operated specimens, there appearing the 
usual number of variously sized medullated fibers. 
It is hardly necessary to say that in the few ganglia of these 
specimens which were stained by the pyridine-silver method no 
trace of the intercellular plexus could be found. 
SUMMARY AND CONCLUSIONS 
The sacral trunk presents many variations in macroscopic 
structure. Asa rule, it consists of three small ganglionic enlarge- 
ments, each ganglion connected with an adjacent one by one 
nerve strand termed by Ranson and Billingsley (18a) the 
internodal segment. The number of ganglia, however, may be 
reduced or increased or the ganglion cells may be scattered 
throughout the length of the trunk. Adjacent ganglia are often 
Fig. 7 A diagrammatic sketch to illustrate the relations and paths of degen- 
erated fibers in the sympathetic trunks of cats which have been operated upon 
as described in the text. The broken lines indicate degenerated fibers. A, level 
of division of the sympathetic trunks; Ant.rt.N.L.4, anterior root of fourth lum- 
bar nerve; B1 to B3, points at which spinal nerve fibers were interrupted by the 
second operation; G.rm.L.4 to G.rm.S.2, gray ramicommunicantes, fourth lumbar 
to second sacral; Gn.L.4 to Gn.S.2, sympathetic ganglia, fourth lumbar to second 
sacral; Int.seg.L.4 to Int.seg.S.1, internodal segments, fourth lumbar to first 
sacral; N.L.4 to N.L.7, fourth to seventh lumbar nerves; N.S.1-N.S.2, first and 
second sacral nerves; Sp.gn.L.4, fourth lumbar spinal ganglion; W.rm.L.4, white 
ramus communicans of the fourth lumbar nerve. Note that no undegenerated 
fibers of central origin can reach the sympathetic trunk caudad to the seventh 
lumbar internodal segment. 
