ME. J. L. CLAEKE ON THE INTIMATE STEUCTUEE OF THE BEAIN. 
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in mammalia. 11, restiform body; 12, grey substance within it; 13, large 
band of fibres arising from it, and crossing obliquely to the anterior part of 
the opposite side of the medulla, decussating with its fellow ; 14, trunk of 
the vagus nerve. 
Fig. 34. Group of multipolar cells giving origin to the anterior root (8) of the left vagus 
nerve, as shown in preceding figure ; — 6, left wall of the canal lined with epi- 
thelium; 13, 13, decussating band of fibres; magnified 100 diameters. 
Fig. 35 represents a transverse section of the right anterior pyramid (y) and olivary body 
(W) of the Cat. The olivary body consists of three separate portions. 
Fig. 36 represents a transverse section of the right lateral half of the medulla of one of 
the higher Apes. The structure is peculiar. The highly developed and 
convoluted olivary body (W) is imbedded in the anterior pyramid, and a 
separate column ( d ) is on its outer side. 
Fig. 37. Transverse section of the right anterior pyramid and olivary body of the Orang 
Outang. The olivary body largely developed, and its lamina thrown into 
numerous folds. 
Fig. 38. Transverse section of the floor of the fourth ventricle of the left side, from the 
human medulla, on a level with the upper roots of the vagus nerve : — J, upper 
part of column of large multipolar cells constituting the hypoglossal nucleus. 
Some of the cells on its outer side are elongated outward, and send their pro- 
cesses in the direction of the vagus nucleus (t, H) and of the nerve (y). It is 
immediately overlain by the column K', which consists of smaller cells and 
numerous longitudinal fibres, and which we saw lower down, much reduced in 
size, in fig. 25. This column is in its turn overlain by the vagus nucleus, 
between which and the hypoglossal nucleus (J), it is almost entirely imbedded. 
If we suppose the lower part of the central canal ( h ) in fig. 25 to open into 
the floor of the fourth ventricle, and the parts on its left to be thrown aside 
outward, the three nuclei (J, K', H, fig. 25) will assume the position which 
they occupy in fig. 38. 
Fig. 39. Similar section a little higher up, on a level with the roots of the glossopha- 
ryngeal nerve. The hypoglossal nucleus has almost wholly disappeared, a few 
small cells only (J, J') remaining with a few nerve-roots. T, dark oval group 
of cells, increased in size from fig. 38 ; K', in the fasciculus teres , much 
increased in size; i, inner nucleus of auditory nerve; t, glossopharyngeal 
nucleus with its club-shaped group of cells. It is overlain by the junction of 
the auditory nucleus (i) with the fasciculus teres ; U, lower end of column of 
large multipolar cells constituting the nucleus of the motor root of trigeminus 
nerve. It is connected, by a plexiform system of fibres (U'), with both the 
fasciculus teres and the glossopharyngeal nucleus, especially the latter ; n, 
slender longitudinal column of fibres. 
Fig. 40. Similar section still higher up. The inner auditory nucleus (i) has become 
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