Drxon— On the Development of the Branches of the Fifth Cranial Nerve in Man. 48 
from it (fig. 8). The third nerve does not touch the ganglion, while the fourth, 
on the other hand, runs into it. In embryo Mr. (8th week), a large ganglion is 
present, connected above with the nasal nerve, and below with the third, ‘and 
occupying a position corresponding to that of the ciliary ganglion of the adult. 
In this embryo no ganglion was found on the frontal nerve. It seems then, as if 
the ganglion present in C. R., in connection with the fourth and frontal nerves 
has, by a migration of its cells, come in Mr, into relation with the third and nasal 
nerves. This explanation is not inconsistent with the imperfect observations 
made on F. M. (7 weeks), a stage intermediate between C. R. and Mr. (page 28). 
The structure and origin of the ciliary ganglion in different groups of animals 
has long occupied the attention of a number of observers, and most conflicting 
accounts have from time to time been published, not only regarding its origin, 
but also in regard to the cells which compose it. By some authors the ciliary 
ganglion has been described as the equivalent of a spinal ganglion, and as belong- 
ing to, the third nerve, to the ophthalmicus profundus, or to the ophthalmic itself. 
Others, again, have described the ganglion as being purely sympathetic, or as 
being composed of two distinct portions, one apparently sympathetic, the other 
equivalent to a spinal ganglion.* 
Schwalbe,} as is well known, first attempted to prove an homology between 
the collections of ganglionic cells, found in various animals, in the course of the 
third nerve, with the ciliary ganglion of the human adult. He came to the con- 
clusion that the ciliary, which he called ganglion oculomotorii, was the equivalent 
of a spinal ganglion, and that its proper connection with the brain was the third 
nerve. Schwalbe has really only proved the existence of nerve cells in the course 
of the third nerve of many animals, and his supposition that the ciliary ganglion 
represents a spinal ganglion has not been borne out. Schwalbe has, however, 
had many followers in assigning the ciliary ganglion to the third nerve. Much 
more recently on quite different grounds, and in a totally different manner the 
ganglion has been referred to the third nerve. I believe that my observations 
prove that the ciliary ganglion in man, when it is first recognisable, has no 
connection whatever with the third nerve. With regard to the connection of the 
third nerve with a ganglion, Professor His says{—‘ Es ensteht der Oculomotorius 
als ein rein motorischer Nery und als solcher hat er kein angebornes Recht auf 
* For an account of recent Papers on the ciliary ganglion, see Dohrn, ‘‘ Uber die erste Anlage und 
Entwicklung der Augenmuskelnerven bei Selachier und das Einwandern von Medullarzellen in die 
motorischen Nerven,” Mittheilungen aus der Zoologischen Station zu Neapel, 1891, Bd. x., p. 1. 
+ ‘Das Ganglion oculomotorii,” Jenaische Zeitschrift fiir Naturwissenschaft, 1879, Bd. xiii. Also 
“Lehrbuch der Neurologie,” 1881, p. 819. 
{ ‘Die Morphologische Betrachtung der Kopfnerven,” Archiv fiir Anatomie und Physiologie. Anat. 
Abtheilung, 1887, Heft. vi., p. 421, 
TRANS. ROY. DUB. SOC., N.S, VOL, VI., PART I, H 
