1895.] Brandies of the Fifth Cranial Nerve in Man. 489 



1. Before the ophthalmic nerve is present in the embryo, a cellular 

 cord stretches upwards and forwards from the Gasserian ganglion, 

 and occupies the place of the future nerve. This is easily demon- 

 strated in the rat, and a similar condition appears to prevail in the 

 human embryo. 



2. Axis-cylinder processes grow out from the cells of the Gasserian 

 ganglion into this cellular cord, and in this manner the ophthalmic 

 nerve is formed. 



3. The axis-cylinder processes increase in number, while the cells 

 of the original cord become fewer and at the same time become 

 disposed around the developing nerve. 



4. The first formed ophthalmic trunk corresponds to the nasal 

 nerve of the adult. 



5. The frontal nerve is formed later, and the proximal part in man 

 is united in a common trunk with the proximal part of the nasal 

 nerve; in the rat, however, the nerves in the first instance take 

 separate origin from the Gasserian ganglion. 



6. In mammals no outlying part of the Gasserian ganglion is 

 present as a ganglion, either for the ophthalmic or nasal nerve, in the 

 sense of a ganglion of a posterior nerve-root. 



7. A single undivided Gasserian ganglion gives rise to all three 

 divisions of the fifth nerve. 



8. In the beginning of the sixth week all the important branches of 

 the ophthalmic nerve of the adult are represented in the embryo. 



9. The fourth and frontal nerves are from an early period closely 

 connected. 



10. The ciliary ganglion is first recognisable as a distinct cellular 

 mass at the beginning of the sixth week. 



11. The ciliary ganglion appears, in the first instance, to be more 

 closely connected with the frontal and fourth nerves than with the 

 nasal and third nerves. 



12. Later this ganglion shifts its position, and in the eighth week 

 it has established the connections and assumed the situation that 

 obtains in the adult. 



] 3. The ciliary ganglion can in no sense be the homologue of a 

 spinal ganglion. 



14. The superior maxillary nerve appears as an independent 

 branch of the Gasserian ganglion in the embryo of four weeks. 



15. Soon -the fibres of the superior maxillary nerve spread out 

 horizontally, and are not collected so compactly into a single bundle 

 as are the fibres of the other two divisions of the fifth nerve. 



16. All the important branches of the superior maxillary are 

 present in an embryo of seven weeks. 



17. Meckel's ganglion is present as a distinct cellular mass at the 

 beginning of the sixth week. 



