82 PROFESSOR A. MILNES MARSHALL. 
branchs, Amphibia, and some other forms, as the Crocodile, the 
ciliary ganglion is in the adw/d situated in the trunk of the 
third nerve, and has brought forward very strong arguments 
for regarding this as the primitive position of this ganglion. 
In Scyllium, as is evident from comparing Schwalbe’s figures 
and descriptions of the adult! with the figures and descriptions 
here given of embryos, there is practically no change in the 
adult from the embryonic condition; in the adult, as in the 
embryo, the ganglion is situated in the trunk of the third nerve ; 
it is also situated in the adult in the very same position occupied 
by the ganglion (c.g.) in the embryo, 7.¢. opposite the point 
where the communicating branch from the fifth joins the third, 
and where the third divides into the two branches (111 @ and 
111 4). 
Very strong evidence in support of the view advocated by 
Professor Schwalbe is afforded by the development of the ciliary 
ganglion in the chick. In the adult fowl the ciliary ganglion is 
not situated, as it is in the dogfish, on the trunk of the third 
nerve, but at the base of a short ciliary nerve arising from the 
third nerve. In the embryo chick, at the end of the fourth day 
of incubation, I have already figured? a ganglionic swelling on 
the third nerve, exactly corresponding in position, relations, and 
appearance with the ganglion (c.g.) of the Scy/diwm embryo. Pro- 
fessor Schwalbe, in referring to my paper, has suggested® that this 
ganglion, the existence of which has been somewhat gratuitously 
called in question by Professor Kolliker,* is the rudiment of the 
ciliary ganglion. I fully accept this suggestion of Professor 
Schwalbe’s ; I had, indeed, arrived at the same conclusion pre- 
vious to receiving his paper, and since then I have directed my 
attention specially to the point, and have satisfied myself that 
this ganglion, which in the embryo chick is situated in the trunk 
of the third nerve (in the same position held by the ciliary 
ganglion in both the embryo and the adult Scy//iwm) , becomes the 
ciliary ganglion of the adult, which is no longer situated im the 
trunk of the third but on one of its branches. 
I think that this fact, that the ciliary ganglion of the chick 
embryo occupies the position that it retains throughout life in 
the Elasmobranchs and Amphibia, supplies the embryological 
Naturwissenschaft,’ 15 November, 1878, and “ Das Ganglion Oculomo- 
torii,”’ ‘Jenaische Zeitschrift fiir Naturwissenschaft,’ Bd. xiii. It is to 
the latter paper, which is much the more complete, that I shall refer in 
future. 
1 Loe. cit., Taf. xiii, fig. 10. 
2 Loc. cit., plate ii, fig. 22. 
3 Loe. cit., p. 60. 
4 « Entwicklungsgeschichte des Menschen u. der Hoheren Thiere,’ 1879, 
622. 
p- 
