SACRAL SYMPATHETIC TRUNK OF CAT 91 
It is not the writer’s purpose to present in this paper a complete 
account of the normal microscopic structure of the sacral and 
eoceygeal sympathetic trunks. Only observations which are 
essential to a correct interpretation of the experimental results 
are included. This applies particularly to fiber counts. The 
counts given below for normal specimens were not planned to 
be more than approximately correct. For the purpose of this 
paper, perfect counts would be no more useful as they would 
not alter the significance of the experimental results which were 
obtained. 
Three cats were used for normal preparations. The right 
trunks were stained by the pyridine-silver method and the left 
were fixed in osmic acid. The preparations of one of these 
specimens will be described and used as a basis for comparison 
and contrast with the experimental material. 
The ganglia. The sacral and coccygeal ganglia present the 
same general features microscopically as the ganglia of the more 
cephalad portions of the trunk. The nerve cells, however, 
appear to be more irregularly and more widely scattered through 
the internodal segments. Serial sections show that many 
internodes contain ganglion cells throughout their entire length. 
Figure 4 shows a section taken approximately midway between 
the first and second sacral ganglia and it contains five nerve 
cells. 
The intercellular plexus has been described fully and the 
literature pertaining to it considered by Ranson and Billingsley 
(18a, p. 337, et seq.). In the writer’s preparations. of the 
sacral and coccygeal ganglia this plexus is well stained and shows 
Fig. 1 A diagram of the lower part of the sympathetic trunk, the associated 
spinal nerves, and the gray rami communicantes as far caudad as they were 
dissected. From a drawing by Dr. Paul R. Billingsley. The line at A shows 
the level of division of the trunk in the first operation. The lines B1 to B7? 
indicate the points at which the spinal nerve roots were divided in the second 
operation. Gn.L7, seventh lumbar ganglion; Gn.S1 to Gn.S3, the sacral ganglia; 
Gn.C1 to Gn.C4, first to fourth sacral ganglia; Int.seg.L7 to Int.seg.C3, internodal 
segments from the seventh lumbar to the third coccygeal; Rm.S1 to Rm.C4, 
gray rami communicates, first sacral to fourth coceygeal; Sp.gn.S1, first sacral 
spinal ganglion; Sp.N.S1 to Sp.N.C4, spinal nerves, first sacral to fourth cocey- 
geal; V.R., ventral root of spinal nerve; D.R., dorsal root of spinal nerve. 
