Literary Notices. xxxv 



tion with the mid-brain by means of a narrow mass of cells, the ante- 

 rior root. The posterior and stronger root has meanwhile become at- 

 tached to the medulla. The anterior root now suffers regressive devel- 

 opment until at 26 days nothing remains but a group of cells in the 

 wall of the mid-brain. The discussion of the Trigeminus group is 

 summarized as follows : 



1). The general proton divides proximally into two roots, of which 

 the posterior has the more complicated and important development. 



2). The posterior root produces mandibular and ophthalmic pro- 

 jections, from the former of which develop the ramus mandibulars 

 and later the ramus maxillaris from the latter the ramus ophthalmicus 

 profundus. 



(g|&¥ 3). In the central part and in more intimate connection with the 

 mandibular projection the Gasserian ganglion develops, and in the per- 

 ipheral part of the ophthalmic projection there develops the ciliary gan- 

 glion (Mesencephalic). 



4) . The anterior root undergoes a regressive alteration ; its dis- 

 tal part produces, in connection with the central part of the proton the 

 ramus ophthalmicus superficialis portio trigemini ; its proximal end, be- 

 coming detached from the distal part, remains some time as a transit- 

 ory ganglion, which, according to Froriep, takes part in the formation 

 of the nervus trochlearis, although the latter may be genetically related 

 to the ramus ophthalmicus superficialis, portio trigemini, as stated by 

 Miss J. Piatt. 



5). From the ciliary ganglion there separates a ganglionic mass 

 which may be considered as the ganglion oculomotorii and which pro- 

 duces the primitive nervus oculomotorius . 



These last points are sufficiently striking; and if the fact be final- 

 ly corroborated that the oculomotor and trochlearis nerves are centri- 

 petal in origin, it is certainly true, as the author states, that these 

 nerves must hereafter be studied from an entirely new point of view. 

 Over ten years ago VanWihje insisted that the mixed cranial nerves 

 have no elements analogous to the motor roots of the spinal nerves ; 

 but that the pure motor nerves passing to the eye-muscles are the only 

 cranial nerves passing to the muscles of the somites, and therefore the 

 only ones homodynamous with motor spinal roots. If the facts here 

 adduced are true it would seem that even this comparison is inadmiss- 

 ible and the difficulty of comparing cranial and spinal nerves is still 

 more increased. 



(3). The Facialis group. 



From this proton arise, besides the facial and auditory nerves, the 



