354 S. W. RANSON AND P. R. BILLINGSLEY 
arrangement cannot be entirely accidental; and the most obvious 
functional significance of the dendritic nest would be that the 
two neurones are thereby in position to be activated by the same 
preganglionic fiber. This is now Cajal’s interpretation of the 
pericellular dendritic baskets. Such baskets must not be con- 
fused with the basket-like appearances produced by dendrites 
winding their way between the cells without encircling them as 
has been done by Van Gehuchten and Sala. Functionally similar 
structures are the plate-like endings of dendrites outside the cap- 
sule of another cell as in Michailow’s cells of Type III (fig. 8, 5) 
and the smaller egg-shaped endings of the terminal branches of 
the dendrites of Michailow’s Type IV cells which are also applied 
to the outer surface of the capsule of another cell (fig. 8, c). We 
believe that all of these formations are designed to place two 
neurones under the influence of the same preganglionic fiber as 
illustrated in figure 15, c. 
3. Another arrangement of dendrites which seems designed to 
favor the simultaneous activation of two or more neurones by 
one preganglionic fiber is found in the bi-, tri-, and multicellular 
glomeruli in the human superior cervical ganglion. This is 
illustrated diagrammatically in figure 15, a. Such glomerulae, 
formed by the dendrites of two or more cells, are numerous in the 
human ganglion, and one is illustrated in figure 6. A single 
axon ramifying within such a glomerulus would be in position to 
activate each neurone contributing dendrites to the glomerulus. 
SUMMARY AND CONCLUSIONS 
Although attention is directed in this paper particularly to the 
cephalic end of the sympathetic trunk and the superior cervical 
ganglion, the comments drawn from the literature are for the 
most part applicable to the entire trunk. 
A study of the literature based on the evidence obtained by the 
nicotine and degeneration methods shows that the cephalic end 
of the sympathetic trunk consists of preganglionic fibers arising 
in the upper segments of the spinal cord and terminating in the 
superior cervical ganglion, and that the cells located in this gan- 
glion give rise to fibers which run to terminate in the glands and 
smooth muscle of the head. 
