Dixon—On the Development of the Branches of the Fifth Cranial Nerve in Man. 55 
is very large and beautifully distinct, placed as it is, to the inner side of, and 
slightly below, the trunk of the superior maxillary near its origin. Continued 
into the ganglion is a large Vidian trunk, which, coming from the geniculate 
ganglion of the facial, crosses the otic ganglion on its upper and inner aspect. 
The Vidian in its course also comes close to the outer side of the carotid artery 
just as the latter is passing in between the cartilages of the basis cranii. A fine 
nerve running on the artery communicates with the Vidian in this position ; 
also near this place a fine twig from the nerve of Jacobson joins the Vidian. 
Meckel’s ganglion gives off a number of large branches, which pass down towards 
the roof of the mouth. The longest of these is 1°3 mm. in length. 
From the upper and anterior part of Meckel’s ganglion a fine nerve, with 
which are many nuclei, was traced forwards and upwards, and then outwards, to 
join, apparently, the branch of the third nerve which goes to the ciliary ganglion, 
and also partly the ciliary ganglion itself. This connecting nerve probably 
represents the branch described by Tiedemann and Arnold, and quoted by 
Schwalbe in his text-book.* 
Meckel’s ganglion in this embryo is relatively very large, having an antero- 
posterior diameter of 0°7 mm., and a transverse one of 0°8 mm. 
The examination of the superior maxillary nerve in these five stages shows us 
that the nerve is at first unbranched, and further, that it is not connected with 
any ganglion except the Gasserian, from which it grows. 
A distinct isolated ganglion of Meckel is not present in Br;. (4 weeks), or 
Ru. (Sth week), nor indeed is one figured by Professor Hist in K. O., an embryo 
larger than Ru. Professor His, however, regards the nuclei present among the 
fibres of the maxillary nerve near its origin as the source of the cells of the 
ganglion of Meckel. 
We have seen that these nuclei are present in large numbers at the end of the 
fourth week (Br;.), while in the fifth week (Ru.) they are not so plentiful. This 
observation, together with the fact that Meckel’s ganglion, when it is first recog- 
nizable as such (C.R. beginning of 6th week), lies free from the nerve trunk, 
being only connected with it by fine branches, and is relatively of very large 
size, leads me to believe that the ganglion is not derived from the cells, seen 
among the nerve fibres of the superior maxillary, in the earlier stages. ‘These 
cells may perhaps become a part of the ganglion, but they can scarcely form the 
whole of it. I believe, however, that it is more likely that the cells present at 
the end of the tourth week in Br;. represent the ‘‘ nervenfiihrendes Gewebe” of 
* Schwalbe, ‘‘ Lehrbuch der Neurologie,” 1881, p. 821. 
} ‘‘ Geschichte des Gehirns sowie der centralen und peripherischen Nervenbahnen beim menschlichen 
Embryo,” Abhandlungen d. Konigl. Sachs. Gesellschaft der Wissensch., 1888, Bd. xiy., fig. 3, plate in. 
