THE CERVICAL SYMPATHETIC TRUNK 355 
In fact, the cephalic end of the sympathetic trunk consists 
almost exclusively of fine medullated fibers, most of which vary 
in size from 1.54 to 3.5u. These fibers degenerate in an ascending 
direction after section of the nerve. In pyridine silver prepara- 
tions no unmyelinated fibers can be distinguished in the normal 
sympathetic trunk at this level except for some fine branches of 
distribution from the superior cervical ganglion which happen to 
be included for a short distance in the same sheath with that 
nerve. Our observations along with those of Langley show that 
the superior cervical and stellate ganglia are not connected by 
myelinated commissural fibers and that unmyelinated commis- 
sural fibers if present are very few in number. Physiological 
experiments conducted by Langley failed to show any evidence 
of commissural fibers joining these two ganglia. Physiological 
and histological evidence is also against the presence of afferent 
fibers in the cervical portion of the trunk. 
The nervus caroticus internus in the cat contains, in addition 
to great numbers of unmyelinated fibers, a very considerable 
number of fine myelinated fibers, mostly from 1.54 to 5.54 in 
diameter. The fibers in this nerve do not degenerate after sec- 
tion of the sympathetic trunk in the neck; all or nearly all of them 
are postganglionic fibers with their cells located in the superior 
cervical ganglion. 
The dendrites of the cells in the superior cervical ganglion are 
of two kinds, intracapsular and extracapsular. The intra- 
capsular dendrites are rare in the sympathetic ganglia of mammals 
but abundant in the human superior ganglion. Here they give 
rise to the complicated subcapsular formations that have been 
designated as dendritic crowns and glomeruli. A glomerulus 
may be formed from the dendrites of a single cell or from those 
of two or more cells and is designated accordingly as an uni- 
cellular, bicellular, tricellular, or multicellular glomerulus. 
The extracapsular dendrites are long branched processes which 
run in every direction among the ganglion cells. In pyridine 
silver preparations it is not possible to follow them to their true 
terminations. We have summarized Michailow’s account of the 
termination of these dendrites in preparations stained with 
methylene blue and illustrated them in figure 8. The dendrites 
