Io8 STRONG. [Vol. X. 



of its fibres are rather small, but with a number of medium- 

 sized fibres among them, and a still smaller number of large 

 fibres. The ascending tract of the V contains a few scattered 

 large fibres, and the ventral root of the V (V minor) is coarse 

 fibred. 



After proceeding cephalad .7 mm. it becomes ganglionated, 

 .36 mm. further on its Gasserian ganglion begins to divide into 

 a dorsal and a ventral part, the ventral part at the same time 

 passing through the floor of the cranial cavity and conse- 

 quently lying in the roof of the mouth. Here this ventral por- 

 tion has lost its ganglion cells and becomes the Ramus ophthal- 

 micus trigemini. This partial division of the anterior extremity 

 of the Gasserian ganglion is the only sign of separation 

 between the ganglia of the Rr. ophthalmicus and maxillo- 

 mandibularis trigemini respectively. The R. ophthalmicus con- 

 tinues cephalad and gradually dorsad, thus entering the orbital 

 cavity. .3 mm. cephalad of its separation from the rest of the 

 V, it comes into connection with the III nerve, which divides 

 on its inner side, one part of the III passing up around it, and 

 the other bending forwards beneath it. 



During the remainder of its course the R. ophthalmicus gives 

 off several branches to the skin, which need not be described 

 more in detail here. When it breaks up in the anterior ex- 

 tremity of the head one branch is given off (170), which bends 

 down, pierces a layer of fibrous cartilage which separates the 

 skin from the oral subepithelial layers and divides. One divi- 

 sion, proceeding caudad, is continuous with a branch of the 

 R. palatinus VII. The significance of this connection will be 

 discussed in the description of the latter. The other division 

 of the R. ophthalmicus, possibly together with some fibres from 

 the R. palatinus VII, proceeds cephalad a short distance, and 

 breaks up into a rich plexus, terminating in the epithelium 

 of the roof of the anterior extremity of the oral cavity. This 

 plexus and its terminations are figured in PL VII, Fig. 3, 

 where the plane of the section enables one to obtain a view 

 of its mode of branching and termination. 



The fibres of the R. ophthalmicus V are rather small, but of 

 variable size, and with, perhaps, a dozen and a half coarse 



