_ SACRAL SYMPATHETIC TRUNK OF CAT 103 
are axones of postganglfonic cells which are in the process of 
myelinization. 
The sacral and coccygeal ganglia possess a rich intercellular 
plexus which, so far as comparison has been made, does not 
differ in any essential detail of structure from the intercellular 
plexus in the cervical and thoracic ganglia. It completely 
disappears following descending degeneration of preganglionic 
axones in the lower lumbar and sacral trunk. It must therefore 
be formed by the terminations of preganglionic efferent axones 
which run to the trunk through the lower white rami. 
Regarding the occurrence of commissural neurons in the sacral 
and coccygeal ganglia, it is hardly necessary to add that no evi- 
dence of the presence of such structures has been found. On 
the contrary, all nervous elements stained by the methods em- 
ployed have been traced to some other source or otherwise 
accounted for. While it may be argued reasonably that possibly 
there are nerve elements present which do not stain by the 
methods employed for these experiments, it is to be remembered 
that such structures have never been satisfactorily demonstrated 
to exist by any other method. Further, the extensive observa- 
tions of J. N. Langley have shown that not only are commissural 
fibers not necessary to explain the physiology of the sympathetic 
- system, but that their presence, in the case of certain limited 
reactions, would introduce real difficulties for explanation. 
