26 Drxon—On the Development of the Branches of the Fifth Cranial Nerve in Man. 
The frontal nerve, near its origin, communicates with the fourth nerve by a 
stout branch. At the point where this communication takes place, the fourth nerve 
has just crossed the upper pole of the Gasserian ganglion, and hes to the inner side 
of the frontal nerve (fig. 8, Plate I.). 
In connection with the frontal nerve is a collection of nuclei, which seems 
to represent a “ciliary” ganglion. The nuclei surround the frontal nerve, but 
more of them are placed to the inner than to the outer side of the nerve. The nuclei, 
which seem to be somewhat smaller than those of the cells of the Gasserian 
ganglion, are not very closely packed together in places, and at certain points the 
outline of the ganglion is not well defined. In the sections the ganglion has an 
oval shape, and encloses a section of the frontal nerve. The long axis of the 
ganglion extends from before backwards. The length of ganglion is 0-4 mm., 
width is 0:2 mm., and depth is 0:3. 
The fourth nerve, at first lying to the inner side of the frontal nerve, also 
passes into this ganglion, but its fibres cannot be traced the whole way through it. 
Within the ganglion the fourth nerve is still observed to lie to the imner side of 
the frontal nerve.* 
Although the frontal nerve in this way passes through the ganglion, none of 
its fibres wander out among the ganglionic cells. ‘The nerve remains as a solid 
and distinct bundle as it traverses the ganglion. 
The third nerve runs in much the same direction as the fourth nerve, but 
internal to it, and on a lower plane, and does not touch or communicate with this 
ganglion, but ends near the termination of the sixth below the optic stalk. 
In this embryo, as in Ru, no upper division of the third nerve is present. 
C.R.-. Ophthalmic nerve = 0:24 mm. 
Nasal branch =>) mm: 
Frontal branch = 10) iit, 
Lachrymal nerve =06 mm. 
Supraorbital nerve =0°8 mm. 
Supratrochlear nerve = 0°5 mm. 
Infratrochlear nerve = 0°2 mm. 
Empryo F. M. (seven weeks, 17°5 mm.). Figures 9 and 10, Plate I. 
The ophthalmic nerve is a short trunk arising from the Gasserian ganglion 
just in front of, and below, its upper pole. The direction of this trunk is upwards, 
forwards, and a little inwards, and it crosses the sixth nerve which turns obliquely 
* [ was at first inclined to believe that this aggregation of nuclei, from its relation to the fourth nerve, 
represented a very early stage in the development of the superior oblique muscle of the eyeball. 
