324 
ME. J. L. CLAEKE ON THE INTIMATE STEUCTHEE OE THE BEAIN. 
the postpyramidal nucleus (b') to the opposite anterior pyramid (y'), those from 
the opposite side decussating each other in front of the canal. The anterior 
pyramids have now ceased to derive their fibres from the lateral columns of the 
cord. 
Tig. 6. Similar section just above the decussation of the pyramids. The restiform 
nucleus ( o ), the postpyramidal nucleus (£>'), and the grey tubercle of Rolando, e 
(caput cornu posterioris), are still further enlarged. The decussating fibres 
from b o, the postpyramidal and restiform nuclei, instead of entering the 
anterior pyramids y y, now proceed to the lower ends of the olivary bodies 
(W, W). The spinal-accessory nucleus (t) and the hypoglossal nucleus (t') 
are still further developed, r is the spinal-accessory nerve. 
Fig. 7. A similar section of the medulla nearer the point of the calamus scriptorius. 
The inner and outer restiform nuclei ( o and d) are much enlarged, and the 
white substance (c) of the restiform body is overlain by the posterior pyramid 
( b ) and its contained nucleus ( V\ also increased in size. The hypoglossal nerve 
(w) is seen to enter its nucleus (l 1 ), which, like the spinal-accessory nucleus (t) is 
further developed. The olivary bodies (W) increase in size ; s is the antero- 
lateral nucleus.. 
Fig. 8 is a similar section just below the calamus scriptorius. The posterior median 
fissure has just begun to open into the fourth ventricle. The grey nuclei of 
the posterior pyramids and restiform bodies nearly coalesce, the dotted line, 
b 11 (on the right side), defining the limits of each. The olivary bodies are 
much increased in size. 
Fig. 9. A similar section through the fourth ventricle, a little above the calamus scrip- 
torius. The grey nuclei of the posterior pyramids and of the restiform bodies 
on each side have entirely coalesced. The spinal-accessory nucleus has now 
become the vagal nucleus (g), und is more distinctly separated from the 
hypoglossal nucleus (t 1 ). At U is seen a small group of cells forming the 
lowest end of the nucleus of the motor root of the trigeminus. 
Fig. 10. Similar section of the medulla on a level with the upper roots of the vagus 
nerve. The hypoglossal nucleus (t 1 ) is brought to the surface of the ventricle, 
while the vagal nucleus (g) is partly sunk between it and the rudiment of the 
inner auditory nucleus (i) which is developed out .of the posterior part of the 
vagal nucleus (g) and the inner part of the posterior pyramid (b, fig. 9). The 
convolutions of the olivary bodies are more numerous than in fig. 9. 
PLATE IX. 
Fig. 11. Posterior view of human medulla oblongata: — a, its lower end; bb\ the poste- 
rior pyramid of right side ; c, right restiform body ; d, lateral column ; e, grey 
tubercle of Rolando, or caput cornu posterioris ; g , pyriform nucleus of vagus 
