1881.] Comparative Neurology. 103 
COMPARATIVE NEUROLOGY. 
BY S. V. CLEVENGER, M.D. 
[ Continued. | 
T this stage the so-called afferent commissure alone is estab- 
lished, but the same law of unification of segments in the 
construction of an individual from its component colonial mem- 
bers will also confer upon it an efferent commissural system. 
While this is intended to represent the visceral nervous system 
of Invertebrata, the same rule will apply in the union of vertebral 
ganglia segments in higher forms, beginning in such Invertebrata 
as possess more than one secondary system ganglia (some 
Arthropoda). 
Ganglionary fusions occur in parasitic insects and other forms, 
but this is secondary and does not interfere with the general 
application. By omitting the afferent part of the fibers that form 
the commissures, the segmental union may be expressed thus, 
and confusion avoided : 
Pe ee 
O—O0—O0—O0—O0 
pe ee 
These may be schematically expressed in diagrams which show 
the higher ganglionic series to be commissurally connected with 
the lower. Each higher segment presiding over a lower system 
series and the commissures between forming apparently, direct 
projection systems. 
This scheme would explain why the splanchnics have no inhibi- 
tory control over the intestines (Ludwig and Haffter), such control 
really pertaining to higher projections (Ott). 
Perfect 3d System. 
Imperfect 3d System. Restiform Columns. 
Spinal Segments, 
Splanchnics, etc. 
Vaso Motors. 
Intestinal. 
