SACRAL SYMPATHETIC TRUNK OF CAT 89 
The writer is indebted to Dr. P. R. Billingsley for doing the 
operation on several specimens and for the dissection illustrated 
in figure 1. 
OBSERVATIONS 
Normal specimens 
As a continuation of the lumbar trunks the sacral portions 
converge rapidly and lie in close contact with the caudal blood- 
vessels. Each trunk possesses, as a rule, three ganglionic enlarge- 
ments, but internodal ganglionic swellings were frequently seen. 
The first sacral ganglion is the largest of the three and was found 
constantly present in all specimens examined. The second 
sacral ganglion is much smaller than the first and occasionally 
its cells were scattered through the internodal segments so that 
there was not present any single distinct ganglionic enlargement. 
The third pair of ganglia was present in all specimens examined 
and the ganglia were of slightly larger size than the second. The 
coceygeal trunks were followed caudad to the eighth ganglion 
and appeared to be more constant in macroscopic structure than 
the sacral. 
The internodal (or interganglionic) segments of both sacral 
and coceygeal portions of the trunk were found to be most vari- 
able as to size and number. In most cases the internodal segment 
was represented by two or three separate nerve strands and any 
number from one to five was not infrequently seen. Fusion of 
opposite ganglia and connection of opposite trunks by nerve 
strands was found in practically all specimens, and in many 
cases it was impossible to say with certainty which strands 
belonged to the right internode and which to the left. 
The coccygeal trunks diminish rapidly to mere thread-lke 
filaments, and in their dissection a binocular microscope of low 
power was a most valuable aid. Gray rami were dissected out 
as far caudad as the fourth coecygeal ganglion. 
The gray rami of the sacral and coceygeal region leave the 
trunks, as a rule, near the caudal poles of the gangla, but a 
good many were seen which followed the internodal segments 
for half their length or even more before diverging from the 
trunk. 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 33, NO. 1 
