Chapter XX 



RECONSTRUCTION OF THE GRAY MATTER IN THE 

 BRAIN STEM OF TROGLODYTES NIGER 



IN the rfconstriution ol the high ceTNical lexcl of the spinal eorcl, the 

 ventral gray column has ahxady het'ii .se])aratecl Irnin the ei'ntral gray 

 matter h\ the (leeussatmn ol the p\raniiclal traet. The eentral gray 

 mattt'r itselt is c|uadrilateral in sha])i' with a \'entroinedian prolongation. It 

 is situated ni its usual eentral position. 



The \eiitral gra\ eolunin is irregularly triangular in outline with its 

 base directed ventronH'siall> , its apex xcntrolatcrally. The dorsal horns are 

 long, compressed laterallx and situated almost m tlu' transverse meridional 

 line ol the cross section. Their perijihcral expansion lorming the substantia 

 gelatinosa trigemini is bulk\, roughly o\al and presents the tendency 

 towards the rather llame-like conliguration which has been tound to be 

 characteristic ol this nucK-ar mass. 



The sensory nucleus ol Goll has already mack' its appearance, being 

 elongated from before backward and lying as a more or less laterally 

 compressed strand of gray matter within the libers of the column of 

 Goll. It IS surrounded on all sides, except at the base, where it is con- 

 llueiit with the central gray matter, by the eiu'clopiiig libers of the column 

 of Goll. 



In general, the high le\el of tlu' eer\ical spinal cord is identical in 

 arrangement with cross sections ol the human brain stem. It becomes appar- 

 ent m the studu's ol these simian sections that the human pattern is being 

 more closel\- approached, both in extent and in complexitxof organization. 

 Many ol the lewis of tlu' chimpanzee and of gorilla are indistinguishable 



irom similar sections of the human neuraxis. 



6o(j 



