58o THE HIGHER ANTHROPOIDS 



nu-clullar\- substance constit iitinij; the eoluiiin ol doll (CG). Neither at 

 tliis level nor at an\ lower le\tl Is there evidence of the unpaned median 

 nucleus of" Bischoll. This fact adds substantiation to the theory already 

 acKanced that the nut'lcus of Bischoll is a functional response to the de\elo])- 

 nient of a tail, jxuticulailx in such forms as specialize this caudal appendage 

 as a prehensile, support mg or locomotor organ. In general, the nucleus ol Goll 

 presents a more disseminated and scattered appearance than is the case with 

 the lower or intermediate primates. In tact the solidarity ol Goll's mick'us 

 in most of these lower forms is one of its distinguishing characteristics. 

 The nucleus of Burdach (NB) has not attained its full dimensions, it 

 does, however, appear as a more compact nucleus than that ol Goll and is 

 surrounded bv a dense lield of mxclinizcd libers torming the column ol 

 Burdach (CB). Lateral to the column of Burdach is a large nuck-us of 

 Rolando, or sul)stantia gelatinosa trigemini ( N R ), whose outer margin 

 is in contact with a well-marked descending trigeminal tract (Trd). The 

 substantia gelatinosa trigemini is in continuit\' whh the rc-mnant ol the Neu- 

 tral gra\- column which now |)rcsents an indelinite outline and appears to 

 be merging with the reticular lormation ( Re I ). 



Dorsal to the pxramid ( Py ), situated along the median ra[:)he, arc the 

 collected axons arising from the internal arcuate libers ( Fai ) which torm the 

 mesial fillet. The a])parent increase in densit\ of this lasciculus implies a 

 certain degree of increment in this central pathway lor the coiucyance ol 

 impulses of discriminative sensibility. 



LEVEL THROIGH THE MIDDLE OF THL IM-EKIOK 01,l\ E (FIG. 258) 



At this le\el the most ijronounced change is ck'tcrmiiuci 1)\ the appear- 

 ance of a large convoluted structure constituting the inU'rior oli\ary nucleus 

 (10). This structure, situated dorsolateral to the p\ramid iP\ ), has in 

 association with it the mesial and dorsal accessory oli\es (,D0, \0). 



