330 
ME. J. L. CLAEKE ON THE INTIMATE STEUCTUEE OF THE BEAIN. 
ficial grey layer covered with columnar epithelium ; h! 1 , median furrow of 
ventricle ; Q", principal nucleus of facial nerve ; i, inner auditory nucleus. 
Fig. 51. A similar section a little higher up, including the grey tubercle of Rolando: — 
g'", superficial grey layer of ventricle ; T", cut end of longitudinal portion of 
loop of facial nerve ; Q", principal nucleus of facial ; q", facial nerve ; e e', grey 
tubercle ; c' o, remains of outer auditory nucleus ; i, remains of inner auditory 
nucleus, sending fibres to Q". 
Fig. 52. Transverse section of fourth ventricle of Rabbit on left side. 
Fig. 53 shows the course of the root of the facial nerve ( q ") from without inward in the 
Sheep. 
Fig. 54 shows the same in Man. 
Fig. 55 represents a longitudinal section of loop of the facial nerve in the plane of its 
course, in Man : magnified 100 diameters. 
Fig. 56 shows a transverse section of the fourth ventricle in Man, on the left side 
along the root of the facial nerve : — g", superficial grey layer ; g'", group of 
cells on its outer part ; above this are the cut-ends of three blood-vessels in 
their sheaths ; T", cut-end of longitudinal portion of loop of facial nerve ; 
A", median furrow of ventricle ; Q", principal nucleus of facial nerve ; q", facial 
nerve; q'", grey streak in its middle, behind which is a blood-vessel and 
streaks of longitudinal fibres. The under portion of the nerve is seen entering 
the nucleus (Q"); its remaining fibres decussate with those of the superficial 
portion ( l ') of the nerve ; the chief portion enter T" and become longitudinal 
along the loop ; the rest pass in front of the loop to the raphe beneath the 
median furrow ( A ") ; V', the sixth or abducens nerve, breaking up into a net- 
work of bundles enclosing longitudinal fasciculi, and becoming connected 
with the inner part of Q". 
PLATE XIV. 
Fig. 57. Horizontal and longitudinal section along the left side of floor of the fourth ven- 
tricle in Man, extending from the upper end of the hypoglossal nucleus (J) 
to the lower end of the facial nucleus (Q ") : — do is the outer auditory nucleus ; 
e', the base of the grey tubercle or caput cornu posterioris ; Q", the facial 
nucleus; T 7 , lower end of the loop of facial nerve, diverging and curving 
outward and downward round Q" ; g"\ the superficial grey layer of ventricle ; 
A", the median furrow of ventricle overlying the raphe. At the lower end of 
the figure, H is the vagus nucleus ; J, the cells of the upper and tapering end 
of the hypoglossal nucleus ; J', a longitudinal plexus of fibres running from 
the facial nucleus (Q") to the hypoglossal nucleus (J). 
Fig. 58. A similar horizontal-longitudinal section a little deeper from the surface of 
the ventricle. Figs. 59 & 60 are transverse sections of the medulla at the 
