20 Drxon—On the Development of the Branches of the Fifth Cranial Nerve in Man. 
no detailed account of the development of the branches of the fifth nerve in 
man has been published. 
In animals lower in the scale, however, a large number of observers have 
given accounts of the condition of the fifth nerve in the earlier stages of 
development, and also in the adult forms. Among these may be mentioned 
Ahlborn, Scott, Shipley, and Kupffer in Marsipobranchii; Marshall and Spencer, 
Béard, Ewart, Miss Platt, Dohrn, and many others in Elasmobranchii; Strong, 
Wiedersheim, and Plessen and Rabinovicz in Amphibia; Hoffmann and Béraneck 
in Reptiles; His, Marshall, Béraneck, and Goronowitsch in Birds; and recently 
Chiarugi in the Guinea-pig. 
From the observations of these authors it is certain that in Marsipobranchii, 
Elasmobranchii, and Reptilia, at all events, the fifth nerve in the earlier stages, 
and even in the adult of some forms, possesses two distinct ganglia.* From 
the anterior of these two ganglia the ophthalmic division of the fifth, or a part 
of it, takes origin; from the posterior ganglion arise the superior and inferior 
maxillary divisions. In birds and reptiles the superior maxillary nerve is a 
later formation than the inferior maxillary, and is developed as a branch of this 
latter. In man and other mammals, on the other hand, a special ganglion for 
the ophthalmic nerve, in the sense of a ganglion on a posterior nerve-root, is 
not present, although attempts have been made to prove its existence. Further, 
in man the three main divisions of the fifth appear to rise independently from 
the Gasserian ganglion. 
The description given by Professor His of the fifth nerve, in the paper 
above referred to, deals with the origin and early stages in the development 
of the three great divisions of the nerve, as well as with the development of 
the fifth nerve roots. In the present investigations, on the other hand, following 
Professor His’s suggestion, an attempt is made to trace the development of 
the different branches of the fifth, starting with an embryo of four weeks, at 
which time the three main trunks are alone represented. Further, special 
attention has been paid to the development of those nerves, which in the adult 
connect the fifth with other cranial nerves, as the often assumed transmission 
of taste impulses by these connecting nerves adds great interest to their mode 
of origin and earliest attachments. The connections of the accessory ganglia of 
the fifth nerve, and as far as possible the date of their appearance in the embryo, 
* Béraneck also describes two ganglia as present in connection with the Trigeminal in the early 
embryo. ‘Etude sur les Replis médullaires du Poulet.’? Recueil Zoologique Suisse, 1888, vol. iv. p. 337. 
+ This does not seem to be the case in the Guinea-pig ; further, in this animal, at the time of origin 
of the fibrous ophthalmic nerve, a small ganglion is present, which later fuses with the Gasserian. 
Chiarugi. ‘Lo sviluppo dei nervi oculomotore e trigemello,” nota preliminare. Monitore Zool. Ital. y. 
1894), p. 275. 
