44 
BULLETIN OF THE LABORATORIES 
ventral bundle lies ventrad from the median nucleus and is bounded 
laterally by the hypoglossal fibres. Along the anterior surface the 
pyramids are very obvious. Numerous concentric fibres crossing in 
the raphe are also mentioned. ' The jihrae arcifo^nnes which consist of 
oblique fibres springing from the lateral aspect of the pyramids, curve 
dorsally and cephalad to the corpus restiforme, collecting there to a 
considerable bundle, passing cephalad, and disappearing under the 
tuberculum laterale. 
The hypoglossus has two sorts of roots, some resembling in 
origin the roots of the anterior spinal nerves, and a bundle which 
springs from the nucleus above described near the sides of the fourth 
ventricle. There is no doubt that the nerve receives crossed fibres 
from the opposite side and from the longitudinal bundle. 
The accessory. The caudal roots, i. e. those in the region of spinal 
nerves, turn abruptly to enter longitudinal bundles lying in the gray 
and probably arising from the anterior (ventral) cornua. The roots of 
the cephalad division of the accessory with those of the glossopharyn- 
geal and vagus enter the tuberculum Rollandii, pass toward the median 
nuclei, but suddenly turn to form longitudinal bundles not traceable 
to definite nuclei. The fibres from the ventrally situated facialis nu- 
clei converge dorsally, forming a considerable longitudinal bundle on 
either side the canalis centralis, and, turning laterally, pass, without 
crossing, to their exit through the longitudinal fibres of the trape- 
zoideum. 
The nucleus of the abducens lies lateral to the knee of the facial 
root, i. e. in its concavity. The cells of the abducens are of the same 
size and appearance as those of the facialis. The fibres pass ventrally 
and then laterally without crossing. The acusticus consists of the two 
roots, the dorsal root sends fibres to the tuberculum laterale, but a part 
pass beyond to the gray matter of the wall of the ventricle, where they 
possibly terminate in small cells. The ventral root-fibres form numer- 
ous small bundles which, after perforating the lower part of the tuber- 
lum laterale, diverge in several directions. A small part turn abruptly 
dorsally to unite with the dorsal root, the remainder follow the longi- 
tudinal course of the fibrae arciformes to a position within the crus 
cerebelli, where there appears a large nucleus composed of large mul- 
tipolar cells and which may be regarded as the nucleus of the acus- 
ticus. 
The trigeminus has two roots, the larger of which is composed of 
