ME. J. L. CLAEKE ON THE INTIMATE STETICTITEE OF THE BEAIN. 
305 
radiating backward from do are well seen, but not so those in question, which run 
inward from do along the dotted line. In this figure, however, numerous fibres from di 
are seen to sweep through and round the great nucleus ( Q "), and in fig. 50 the same are 
seen at eV". In fig. 57, Plate XIV. many of the horizontal fibres radiating from the 
outer auditory nucleus (do to d) evidently consist of the processes of its large multipolar 
cells. At the lower end of this nucleus or column (d o) there are numerous longitudinal 
streaks of grey substance formed from the post-pyramidal and restiform ganglia, as shown 
in fig. 25, Plate X. The superficial grey layer (</", fig. 57, Plate XIV.) of the ventricle, 
at the side of the median furrow (h!'), as it passes downward becomes reduced to the 
epithelium of the ventricle on the posterior surface of the raphe ; on its outer side some 
longitudinal fibres descend from the longitudinal portion (T") of the loop of the facial 
nerve. This band of fibres inclines somewhat forward as it descends, diminishes in size, 
and becomes continuous with the surface of the column which runs beneath the front 
of the hypoglossal nucleus, between the hypoglossal nerve and the raphe (V, fig. 8, 
Plate VIII. & fig. 32, Plate XI.). At the lower end of fig. 57, Plate XIV., the upper 
tapering end of the hypoglossal nucleus is represented at J, and beneath its inner side, 
the longitudinal band of fibres just mentioned is gradually lost to view. On its outer 
side some plexiform bundles of the white column (J') ascend to the nucleus (Q! 1 ). Still 
further out is the vagal nucleus (H), and beyond this the lower end of the outer auditory 
column do The raphe contains numerous cells of considerable size, and a system of 
antero-posterior fibres. These are crossed nearly at right angles by another set of hori- 
zontal decussating fibres, which are continued upward beneath the superficial grey layer 
that lines the median furrow of the fourth ventricle. The decussating fibres cross the 
longitudinal band on each side of the raphe somewhat obliquely from above downward 
and from within outward. Some of them are certainly connected with cells in the 
raphe, and through these they probably communicate with antero-posterior fibres of the 
raphe, and thus establish a complicated commissural connexion between distant parts, 
or levels, of the medulla. Others are continuous with fibres of the lateral bands, and 
appear also to proceed from the raphe, and not from the opposite side of the medulla. 
The rest of the decussating fibres cross the raphe and the lateral bands from one side 
of the medulla to the other. The upper set extend obliquely downwards and outwards 
to the base (dd) of the grey tubercle (see also d, fig. 51, Plate XIII.). The lower set 
traverse the anterior portion of the vagal nucleus (H). Many of these proceed from 
the cells of the hypoglossal nucleus, as shown in fig. 31, Plate X. 
(64) Fig. 58, Plate XIV. represents a similar horizontal-longitudinal section a little 
deeper from the surface of the fourth ventricle. Figs. 59 & 60, Plate XIV. are transverse 
sections of the left lateral half of the medulla at the upper and lower ends of this longi- 
tudinal section. In figs. 58 & 59 the upper lines of section correspond. F is the raphe 
immediately below the median furrow of the ventricle. V is the white column between 
the raphe and the entrance of the abducens nerve (V') into the nucleus (Q"). d is the 
base of the grey tubercle, d o the outer auditory nucleus. The lower line of fig. 58 
2 u 2 
