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included in the autonomic nervous system as proposed by Langley. As 
a ganglion receiving preganglionic and giving off postganglionic fibers, 
i. e., interposing a second set of neurones in the course of a motor path 
from the central nervous system, it conforms to the general description 
given by Langley (:08°) for the autonomic ganglia. This author separates 
the autonomic system into four subdivisions, viz., the mid-brain auto- 
nomic, the bulbar autonomic, the sympathetic, and the sacral autonomic. 
He shows that the various members of the system have certain cha- 
racteristics In common, but points out that, phylogenetically, they may 
have arisen independently. He thus prepares us for such variations in 
structural details as we find in the ciliary ganglion of birds when we 
compare it with a sympathetic ganglion of the truuk region. 
Ontogenetically the ciliary and sympathetic ganglia in the group of 
birds seem closely related. In a former paper, previously quoted, the 
writer has described the development of the ciliary ganglion in the 
chick from cells which migrate from the mid-brain along the oculomotor 
nerve, and from the Gasserian ganglion along the ophthalmicus and 
ramus communicans. Recently Kuntz (:10) has found evidence in chick 
embryos that the sympathetic gangha develop in a similar way, receiv- 
ing part of their cells from the neural tube by migration along the 
ventral roots of spinal nerves, and part from spinal ganglia via the 
dorsal roots. 
It is not improbable that all parts of the autonomic system have 
arisen in phylogenesis in somewhat the same manner, through a peri- 
pheral migration of cells from more central structures. Varying de- 
mands in different regions of the body have called forth the appropriate 
autonomic nervous mechanisms, and it is not surprising that the unlike 
conditions under which these have arisen find their expression in dissi- 
milarities in structural details. 
In spite, then, of certain differences in internal structure and 
topographical relations, the ciliary ganglion of birds falls into the same 
general system with the sympathetic ganglia. It is the most anterior of 
the autonomic series, and, by virtue of its oculomotor and trigeminal 
connections, belongs to the mid-brain and bulbar subdivisions of this system. 
Summary. This summary is based largely on results obtained from 
the study of the ciliary ganglion in the hen. 
1. The ciliary ganglion of birds is closely related to the oculomotor 
nerve. In the hen, pigeon, and duck the ganglion is situated directly on 
the trunk of the nerve, i. e., no short root normally exists. 
2. The ganglion gives off from its distal end one large nerve and 
a variable number of smaller ones. These together constitute the nervi 
ciliares breves. 
