5-8 THE HIGHER ANTHROPOIDS 



is tlu' loniiula tor all ol the great anthropoids incliKling man, in all ol w hich 

 the column of Burdach is greater than the column of Goll. The tormula 

 representing this relation in some lower prmiates shows the coUimn ot Goll 

 to be greater than that of Burdach. The signilicance ot this in\i'rsion ot 

 sensory rehttion arises from the growing prominence ot manual ditlerentiation 

 seen in the greater anthropoids as well as from the decline ot the sensory 

 representation in the caudal portion of the animal, more particularl\ tlu' tail. 

 The circumferential zotie in the chimpanzee has a considerafjle depth and 

 contains the two ascending spinocerebellar tracts ( Fie, Go\v ). The inter- 

 mediate zone contains the rubrospinal and spinothalamic tracts ( Rst, Spt ) 

 and merges insensibly with the reticular loiniation w hose appearance at this 

 le\-el is somewhat ditfuse. Neither the central gra\ matter (Gen) nor the 

 ventral gray column (Ven) presents any marked specialization, although 

 tht' latter stands out conspicuouslx because of its detachment in consequence 

 of the hca\ydecussationsof pyramidal libers [ Py x ). 



LEVEL OF CAUDAL EXTRE^1IT^ OF INFERIOR OLI\ E (FIG. 2,-7) 



I iere the appearance of tiie section has undergone some change princi- 

 pall\ becaust- of a considerable increase in all ot its diameters. This is occa- 

 sioned both b\ the e\[xinsion of the dorsal st'nsor\ nuclei (NG, NB) and 

 the appearance of a new gray element, tlu' mtt'iior oli\ar\ nuck'us (10) 

 whose caudal tip lit's immcdiatcl.x lateral to tin- p\ramid ( Py ). The central 

 gray matter (Gen) is more conspicuous because ot its dorsal migration 

 into the [josition which it will occup\ in the lloor ot the tourth \entncle. 

 Gontained in its center is a small central canal. It dillers in its appt-ar- 

 ance from all of tlu' lower le\c'ls because ot its complete detachment, 

 due to the interposition of internal arcuate tibeis arising in the nucleus of 

 Goll (NG). These libers also detach the central gra\- matti'r from the 

 nucleus of Burdach (NB) and the substantia gelatinosa trigemini (NR). 



