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. ^Y\\t fibrae arciforjnes which consist of 

 obli(iue 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, /. e. those in the region of spinal 

 nerves, turn abrui)tly 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 \\-\ii 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 %\X.\\dXQ^ 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 abdiicens lies lateral to the knee of the facial 

 root, /. 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 acusticj/s 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 api)ears 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 



