ME. J. L. CLAEKE ON THE INTIMATE STETJCTUEE OE THE BEAIN. 281 
as have the longitudinal columns of cells constituting the nuclei of the hypoglossal 
nerves in the higher vertebrata. Under a magnifying-power of about 100 diameters, a 
transverse section of one of these columns has the appearance represented in fig. 34, 
Plate XI. The cells are large and multipolar, resembling those of the hypoglossal 
nucleus. Between them are numerous longitudinal fibres represented by the dots ; and 
from all parts of the nucleus a number of fibres radiate transversely toward the surface 
(see also fig. 33, 7, on left side), where they bend round and become lost, for there is no 
nerve attached to this part of the medulla. From this nucleus the anterior roots of the 
lower set of vagal nerves take their origin, and curving outward and backward in a thick 
compact bundle (8, fig. 33) join the posterior roots (9), which are somewhat more nume- 
rous, and arise from a large column of grey substance (10, 10) behind and at the side of 
the canal (6). This substance is finely granular, and contains a multitude of very small 
cells or nuclei. It sends numerous fibres into the anterior nucleus (5, see left side 
of figure), as well as others which, in company with those issuing from the nucleus, 
proceed outward to the surface at 7. On the outer side of the posterior nucleus (10) 
is the restiform body (11) containing some grey substance (12), from which numerous 
fibres converge into a large bundle (13) that runs forward and inward to decussate with 
its fellow across the raphe in front of the canal, and terminate on the opposite side in 
the anterior part of the medulla close to the group of cells (3). The correspondence of 
the anterior nucleus (5) and of the anterior vagus-roots (8) in the Fish, with the 
hypoglossal nucleus and hypoglossal nerve in the higher vertebrata, is very striking. 
The arrangement in the Fish is such that the fibres distributed to the tongue, instead of 
running forward across the medulla in the course of the dotted line x as a separate and 
special hypoglossal nerve, are thrown backward and aside at 8 to join the vagus and be 
distributed to the tongue as one of the branches of that nerve *. 
(23) Of the Olivary bodies . — In my memoir on the Medulla, I gave a detailed account 
of the general appearance and structure of the olivary bodies in Man, in the Ape, in 
many of the Mammalia, and in Birds, and I have now only a few more observations to 
make on the subject. In fishes I have never been able to discover any structures to 
which I could point as the representatives of the olivary bodies of the higher animals. 
In Birds, however, they certainly exist, although their cells are not arranged in the 
form of a lamina, but are scattered about the column in which they are contained. 
In the higher Mammalia, however, they assume the form of a lamina, which, in the 
* In reptiles, also, the vagus sends a considerable branch to the tongue, and indeed is the only nerve that 
supplies that organ. This branch must not he regarded as the glossopharyngeal, for it supplies not only the 
muscular tissue of the tongue, but the muscles which protrude and retract that organ. “ La huitieme paire,” 
says Desmoulins, “ est le seul nerf distribue aux muscles de la langue et de la glotte ” ( Systtmes Nerveux, 
tom. ii. p. 455). I have not examined the origin of the vagus in reptiles, hut probably it is similar to that 
which I have discovered in fishes. The spinal-accessory, also, in reptiles and birds is only a part of the vagus, 
which, according to Bischoff, gives one branch, or several branches, to the neck. In reptiles and fishes, both 
the hypoglossal and spinal-accessory are only branches of the vagus, or rather the three nerves form one com- 
mon system. 
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