426 S. W. RANSON AND P. R. BILLINGSLEY 
the fascicle was followed caudad from the superior cervical 
ganglion it was seen to give off very small bundles of fibers which 
left the trunk as gray branches, bringing about a gradual reduc- 
tion in the size of the fascicle. One set of serial sectioris of the 
entire cervical portion of the sympathetic trunk was prepared, 
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Fig.5 The sixth thoracic internodal segment of the sympathetic trunk in the 
cat. Two fascicles may be recognjzed, one appearing in the cross-section as a 
large oval well myelinated field, the other as a crescentic field with few myelinated 
fibers. Osmic acid. X 425. 
and in this preparation it was found that in tracing the crescent 
downward it decreased in size and finally disappeared. It is 
obvious, therefore, that in the upper cervical region a fascicle 
similar to the crescent consists of postganglionic fibers which 
accompany the trunk for a certain distance before being given off 
