32 Drxon—On the Development of the Branches of the Fifth Cranial Nerve in Man. 
Milnes Marshall,* in his account of the development of the cranial nerves of 
the chick, describes an early stage of the ophthalmic nerve, and although he does 
not give it the name of ‘‘nasal,” yet its course shows that it is undoubtedly that 
nerve. Hoffmannt has shown that in reptiles the naso-ciliaris, as he calls it, is 
at first larger than the frontal. We may state, then, that in birds, reptiles, and 
mammals, the nasal nerve appears before the frontal, and is the first representa- 
tive of the ophthalmic division of the fifth cranial nerve. 
In man the nasal and frontal are from the beginning branches of a common 
trunk; this is not so in the rat, as in this animal they at first rise separately 
from the Gasserian ganglion just as they do from the ‘“ ophthalmic ” ganglion in 
reptiles, according to Hoffmann. 
The marked communication between the fourth nerve and the frontal in C.R., 
and in the older stages is of interest, as it probably represents the communication 
described by Schwalbet in the adult as existing between the fourth nerve and the 
trunk of the ophthalmic. Marshall and Spencer§ describe a communication 
between the fourth and the ophthalmic division of the fifth nerve in Scyllium, and 
a very intimate connection between the ramus ophthalmicus superficialis trigemini 
and the fourth nerve is also noted by Miss Platt,|| in Acanthias, and by Dohrn, 
in other Elasmobranchs. I have found this communication well marked in rat 
embryos, but in them, as in man, the communication is rather between the fourth 
and frontal nerves, than between the fourth and ophthalmic.** 
The early development of the ciliary nerves, which are already present in 
F.M. (end of 7th week), is interesting. It is also instructive to note that not only 
is the lachrymal nerve itself present in C.R. (beginning of the 6th week), while 
the lachrymal gland is not developed until sometime in the third month, but that 
also the fine communication which exists in the adult between the superior 
maxillary division of the fifth nerve and the lachrymal nerve can already be 
traced in the embryo of seven weeks (I’.M.). 
* «The Development of the Cranial Nerves in the Chick.” Quarterly Journal of Microscopical 
Science, 1878, vol. xviii, p. 29. 
+ ‘ Weitere Untersuchungen zur Entwicklungsgeschichte der Reptilien.” Morphologisches Jahrbuch, 
1886, Bd. xi., p. 207. 
t ‘‘ Lehrbuch der Neurologie,” 1881, p. 825. 
§ ‘Observations on the Cranial Nerves of Scyllium,” Quarterly Journal of Microscopical Science, 1881, 
vol. 21, p. 472. 
|| ‘‘ A Contribution to the Morphology of the Vertebrate Head, based on a study of Acanthias 
Vulgaris,” Journal of Morphology, vol. y., 1891, p. 79. 
Cy & Uber die erste Anlage und Entwicklung der Augenmuskelnerven bei Selachien und das Einwandern 
von Medullarzellen in die motorischen Nerven,” Mittheilungen aus der Zoologischen Station zu Neapel, 
1891, Bd. 10, p. 1. 
*k Tn **Quain’s Anatomy,” Part II., vol. iii., p. 233, a communication between the fourth and frontal 
nerves is noted on the authority of Berté. 
