MAMMALIAN. 45 



portions of the medulla, and decussating behind the pyramids at the raphe, with 

 fibres derived from the opposite side. The posterior root of the auditory often con- 

 tains at its entrance into the medulla a few scattered cells, which are less conspicu- 

 ous in the sheep than they are either in the cat or in man. They may generally, 

 however, be plainly seen, and were described by Stillmg, in man, as a little ganglion, 

 similar to those found on the posterior spinal roots. In the cat, the posterior root 

 of the auditory is very large and conspicuous (Plate IX, Fig. 34) ; its pyriform 

 swelling is very evident, containing numerous ceUs and fibres, the latter winding 

 among the small cells in a somewhat spiral or serpentine course, resulting apparently 

 from the obliquely ascending course which the posterior auditory roots take as they 

 wind around the restiform body. 



As the posterior root proceeds in its course, winding in a broad band round the 

 posterior border of the restiform body, the cells which are scattered among its inner 

 fibres become more and more numerous ; they are principally oval or fusiform in 

 shape, elongated in the direction of the fibres. As the roots pass \he flocculus, Avith 

 which the medulla is here connected, the cells increase in number and size, and the 

 broad band of nearly parallel fibres soon expands, entering the posterior portion of 

 the auditory nucleus, through which many of its fibres penetrate to the anterior 

 portion. 



The anterior root ( VIII) is also quite well developed, entering close to the pos- 

 terior, which a part of its fibres accompany, the majority, hoAvever, immediately 

 diverging and passing on the inner side of the restiform body, which is thus com- 

 pletely grasped, as it were, by the two roots. In Plate IX, Figs. 33, 34, the develop- 

 ment of the anterior auditory root in the cat is well seen : the roots lie at first just 

 behind those of the glossopharyngeal, from which it is often somewhat difficult to 

 distinguish them. At the point where the anterior roots cross the external band of 

 arciform fibres, a little ganglion or group of cells is developed, in close connection 

 with the roots, the root-bundle often splitting, a part of the fibres going on each 

 side and completely inclosing this little group. 



The network constituting the outer nucleus of the auditory contains very large 

 and numerous multipolar cells, sending their processes in all directions around and 

 among the longitudinal and transverse fibres of which the network is composed. 

 The cells fill the entire network, extending from the apex at the entrance of the 

 anterior roots,, back towards the cerebellum, as far as the entrance of the posterior 

 root, and reaching forwards into the anterior portion of the nucleus, along the back 

 of which a group is formed sending out numerous fibres into the cerebellum. Both 

 nuclei of the auditory are jouied to the caput by numerous radiating fibres, some of 

 which penetrate the caput and pass outwards as internal arciform fibres. 



The fasciculus teres ( T) which becomes the nucleus of the sixth and facial nerves, 

 is first seen as a somewhat dark mass on the floor of the fourth ventricle, in that 

 part of the auditory nucleus which represents the upward extension of the hypo- 

 glossal ; it contains numerous small cells, Avhich increase in size and become more 

 numerous higher up. 



In that portion of the anterior columns of the medulla representing the upward 

 continuation of the lower olivary bodies, numerous multipolar cells are found, many 



