■82 THE HIGHER ANTHROPOIDS 



by expansion of its funckis which (.'ontuins a greater \-oKiiiu- ot ni\ clini/ecl 

 (il)ers than in the low it or intermediate primates. The most cons|)ieu()us 

 features of the olixe in the ehinifxinzee are its cleeisi\e hoLindar\ hne and 

 definition, to<i;ether with a marked degree of eoinokition into which its 

 retaining wall of gra\ matter is thrown. These particulars correspond closely 

 to those of the structure in tlu' human brain, and are in accord with the lunc- 

 tional interpretation gi\en of the inferior olive in this discussion. The 

 advances in oli\ary organization signily a dehnitt' increase m the coordina- 

 tion of simultaneous movements ol hands, head and eyes, in the interest ol 

 the better perlormanee of skilled acts. The chimpanzee is capable ol a remark- 

 able range of performances of this kind, notable because ot their great 

 ra|)idity, precision and force. Animal trainers and scientific ol)servers ha\e 

 alike been impressed b\' the proficicncx and adaptabilit\- which this animal 

 manifests in its manual dexterity. 



The central gra\' matter, which has nearl\ completed its dorsal migra- 

 tion, is about to take up its position m the lloor of the fourth ventricle. In 

 its more ventral portion is a large, w cll-(k'lincd niieU'ar aggregation, the 

 nucleus hypoglossus ( N ii \' ) from which tlu' emergent fibers of the twelfth 

 nerve (N12 ) pass toward the inferior oli\t'. The definition of this nucleus is 

 more prominent than that observed in thclowerand intt'rmcdiate primates. 

 Lateral to the hxpoglossal nucleus in the central gray matter is another 

 nuclear collection of lighter color, with less w cll-derined boundaries, the 

 dorsal nucleus of the \agus ( N\cl ), connet'ted with which are some I'liter- 

 ing root libers ol t lu' piu-iimogastric ner\ e. i.ateral to the central gra\ mattir 

 are the three great nuclei of tlie dorsal sensory field, first the nucleus ol 

 Goll (NG), second, the nucleus of Burdach (NB) and third, the nucleus 

 of Rolando (NR). The nucleus of Goll ( N G 1 is considerably smalUr than 

 the nucleus of Burdach ( N B ), w Inch is at least tw ice the size ol cither ol its 

 sensorv neiulibors. The nucleus of |-5tirdach shows the t\|)ical accessorv 



