ME. J. L. CLARKE ON THE INTIMATE STRUCTURE OE THE BRAIN. 325 
nerve; /, column at side of median furrow constituting the hypoglossal 
nucleus. 
Fig. 13. Side view of the same: — W, olivary body; y, anterior pyramid; A, arciform 
fibres. 
Figs. 15 to 21 represent transverse sections of the medulla oblongata of the Monkey; 
fig. 15, section just below the point of the anterior pyramids. The same 
letters signify the same parts as in figs. 1 to 10 of the human medulla, Plate 
VIII. 
PLATE X. 
Fig. 22. Transverse section of the posterior part of the right lateral half of the medulla 
oblongata of the Monkey at the level of the highest roots of the vagus nerve. 
Fig. 23. Similar section of the whole right lateral half of the medulla: — i, the inner 
auditory nucleus ; d o, the outer auditory nucleus, pierced by numerous lon- 
gitudinal bundles of fibres (represented by the dark masses) ; t", nucleus of 
the lower roots of glossopharyngeal nerve ( g ). 
Fig. 24. Longitudinal and horizontal section of the left half of the posterior part of the 
human medulla oblongata : — b b', white and grey substance of the posterior 
pyramid; o, inner grey substance or nucleus of restiform body; d, its outer 
nucleus ; g, vagal nucleus ; i, inner auditory nucleus ; d o, outer auditory 
nucleus, formed by the fusion of the restiform and postpyramidal nuclei. 
Fig. 25. Transverse section of the spinal-accessory and hypoglossal nuclei of the left side, 
at the level of the lower end of the olivary body : — E, bottom of the posterior 
median fissure ; H, group of cells constituting the anterior portion of the spinal- 
accessory nucleus ; r, the spinal-accessory nerve ; the remainder of the figure 
behind this group is the posterior division of the spinal-accessory nucleus ; 
B, columns of cells and longitudinal fibres, with transverse fibres decussating 
across the middle line with those of opposite side ; below these are decussating 
fibres from the anterior division (H) of the nucleus ; h, central canal lined by 
columnar epithelium; J, hypoglossal nucleus; J", fan-shaped set of fibres 
converging to decussate across the raphe (F) ; K', small column of cells and 
longitudinal fibres, ascending and increasing as it ascends, between the hypo- 
glossal and spinal-accessory nuclei to the “ fasciculus teres ; ” x, roots of 
hypoglossal nerve. 
Fig. 26. Nerve-cells from the outer restiform nucleus of the Monkey; magnified 220 
diameters. 
Fig. 27. Oblique-longitudinal section of the medulla oblongata, carried along the line 
L t, fig. 5, and extending as high as fig. 8 : — n n' is the slender column of the 
vagus and spinal-accessory nerves ; 1 1 is vagus and spinal-accessory nucleus ; 
the dark masses at n" represent the cut-ends of the transverse bundles of fibres 
