58 BULLETIN OF THE LABORATORIES. 



not SO largely charged with cells, the cuneate and clavate nuclei have 

 disapi)eared, the lateral nucleus is still present, while the cells of the 

 formatio reticularis are much more abundant and indicate the begin- 

 ning of a large median nucleus which is quite conspicuous in the next 

 section, (Plate XVI, Fig. 2, e.) This section is taken still farther cepha- 

 lad and is chosen at the entrance of a few fibres of the ninth nerve root, 

 (Fig-. 2, Plate IX ) Most of the fibres of this nerve turn soon after 

 entering the medulla and pass into the longitudinal fasciculi ; some, 

 however, seem to lead directly into a small nucleus, a, which we term 

 a nucleus of the ninth nerve. At this level we find the cells of the 

 lateral nucleus increasing in number and size and forming quite a large 

 aggregate which can easily be traced as the caudad extension of the 

 seventh nerve nucleus. We have in this section also the first few 

 fibres of the eighth nerve passing in above the restiform body to a 

 large mass of gray matter densely packed with small cells, which we 

 shall term the internal nucleus of the eighth nerve. 



The next section is taken at about the level of the middle of the 

 entrance of the eighth nerve and at the union of the cerebellum with 

 the medulla by the pedunciilus cerebeili, (Plate XVI, Fig. 3.) The 

 eighth nerve enters as a large bundle, /, and just within the border of 

 the medulla is located the nucleus of the root of the eighth nerve, c, 

 composed mostly of rather small cells. 



Following the fibres as they pass into the medulla we find that 

 some of them pass dorsad to the restiform body, f, and enter Deiter's 

 nucleus, b, in the peduncle of the cerebellum and some turn directly 

 into the cerebellum. Of those fibres which pass ventrad to the resti- 

 form body, part turn dorsad and enter Deiter's nucleus from below and 

 perhaps pass through the nucleus into the cerebellum. 



The remaining fibres pass through a reticular formation and enter 

 the internal eighth nucleus which is on the floor of the fourth ventricle 

 at d, Fig. 3, Plate XVI The cells of Deiter's nucleus are of the or- 

 dinary multipolar type, measuring about .05 mm. in length. The en- 

 trance of the eighth root is also shown on Plate XVI, Fig. 6, as is 

 seen in a longitudinal section taken parallel to the base of the medulla. 

 As most of the fibres pass dorsad upon entering the medulla the only 

 nucleus of the eighth shown at the level of the entrance is the nucleus' 

 of the root, b, of the figure. 



Besides the nucleus of the raphe and adjacent formatio reticularis, 

 e, of the section, (Plate XVI, Fig. i,) the only other group of cells 



