300 S. W. RANSON AND P. R. BILLINGSLEY 
there are no sensory fibers in the cervical sympathetic trunk, 
since stimulation of this trunk produces no reflex effect through 
the spinal cord. Since no one has ever claimed that this ganglion 
contained sensory elements, it is not necessary to discuss this 
question in detail here. The question of the presence of sensory 
neurones in the sympathetic ganglia was discussed at some 
length in the section of this paper dealing with the dendrites. 
The negative evidence (the absence of fine branching axons in the 
ganglion after degeneration of the preganglionic fibers) which 
indicated the absence of connections between the sympathetic 
ganglion cells would also speak against the existence of sensory- 
motor synapses. 
Synapses between pre-and postganglionic neurones are the only 
ones of which physiological experiments have given evidence. 
These are also the only ones that have been demonstrated 
histologically. The clearest demonstration has been given by 
Huber (’99) on the frog (fig. 13 and 14). In preparations stained 
with methylene blue he was able to trace the fibers of the white 
rami into the trunk ganglia and see them divide repeatedly. 
Some of these branches he was able to follow to their termination 
as subeapsular pericellular baskets. In a well stained ganglion 
it could be seen that the cell body of each neurone was enclosed 
in such a pericellular plexus. As a rule, the fibrillae of the plexus 
form a closed network, but now and then fibrillae were found end- 
ing free. Similar pericellular plexuses were observed by him in 
the trunk ganglia of mammals and here again the evidence pointed 
to their being the endings of fibers from the white rami. These 
pericellular plexuses have been seen by others, including Ehrlich 
(96), Retzius (’89), Arnstein (’87), Aronson (’86), Sala (93), 
Van Gehuchten (’92), v. Lenhossék (’94), Dogiel (’95), and 
Kolliker (96). 
Dogiel (95) and Huber (713) could not determine whether all 
or only a part of the cells of a sympathetic ganglion were sur- 
rounded by pericellular plexuses. I take these statements to 
refer to the mammalian ganglia since Huber (’99) has himself 
shown that all these cells are so surrounded in the frog. For a 
full account of this form of synapse the reader is referred to 
