CAEPENTER: DEVELOPMENT OF THE OCULOMOTOR NERVE. 147 



raxons may enter the third nerve in the cavernous sinus, where it comes 

 into close relation with the cephalic extension of the cervical sympathetic 

 system. 



The only description of a sympathetic root of the avian ciliary ganglion 

 to be found in the literature is that of Eochas ('85), who detected in the 

 goose several fine fibres extending to the ciliary ganglion from the sym- 

 pathetic plexus about the ophthalmic artery (Weber's plexus). 



Ciliary Nerves. There is much variation in the number of ciliary 

 nerves given off by the ciliary ganglia of different species of birds. Va- 

 riations may also occur among individuals of the same species. Schwalbe 

 ('79) states that the number may vary from one in many birds, includ- 

 ing the hen, owl and goose, to seven in parrots. 



Schwalbe figures for the goose a ciliary nerve (ramus ciliaris trigemini) 

 emerging from the ophthalmic branch of the trigemimis distal to the ori- 

 gin of the communicating branch passing to the ramus ciliaris ooulomo- 

 torii. Holtzmann ('96) shows that in the hen the communicating 

 branch gives off an independent ciliary nerve to the eyeball. 



b. Histology. 

 1. Oculomotor Nerve. 



In birds, as well as in man (Barratt, :0l) and in teleosts (Herriclt, '99), 

 both large and small meduUated neuraxons are present in the oculo- 

 motor nerve. This has been shown to be the case in the pigeon by 

 Langendorff (:00), who found the main portion of the nerve composed 

 of neuraxons of large calibre, while smaller ones occurred near the 

 periphery. In all forms the majority of the small neuraxons pass into 

 the ciliary ganglion. 



2. Abducent Nerve. 



I have not been able to find any description of the finer structure of 

 the abducent nerve in birds. In man it is made up of large and small 

 meduUated neuraxons (Barratt :0l). 



3. Ciliary Ganglion and Short Ciliary Nerves. 



Anatomical Evidence. The character and connections of the cells of 

 the ciliary ganglion of vertebrates have long been favorite topics of inves- 

 tigation among neurologists. 



Before the silver impregnation process of Golgi had come into general 

 use, Eetzius ('81) had already demonstrated by other methods the multi- 



