7o8 THE HIGHER ANTHROPOIDS 



results of specialization of the hiiulcr portions of the body. In mycetes, the 

 coefficient of Coil's nucleus is greater than in all other primates, and as this 

 is xhv onl\ form of all those considered which possesses a highly developt'd 

 prehensile tail, the signilicance of sensory specialization in this region ol the 

 body becomes apparent. The decrease of |:)rehensile lunction ot the tail and 

 the final disappearance of this organ would of necessity occasion a progres- 

 sive diminution in the nucleus of Coll. Certain adaptive modifications in the 

 feet and legs making provision for one kind or another of specialized loco- 

 motion, either in tree life or upon the ground, would rellect themselves quite 

 as much upon this nucleus. In those instances in which the tail appears to 

 play no conspicuous part, the maintenance of the standard dimensions in 

 GoII's nucleus may be regarded as due to factors operati\e in connection 

 with specialization in the hindlimb and particularly the toot. 



But c|uite apart from the size of this nuclear relay station, emphasis 

 should be laid upon another feature in the dorsal sensory field. The column ol 

 Coll, comprising the ascending fibers from proprioceptors in the hind por- 

 tion of the bod> , inchiding the tail wlu-n pri'sent, shows a progressi\-e tend- 

 ency to decrease in passing from the lower to the higlu'r primates. The 

 actual volume of mechillary libers serving tor the purpose ot sensory conduc- 

 tion In the column of Coll in lemur compared with gorilla is something 

 slightly less than one-half. This indicates a distinct falling oil in the \olume 

 of afferent impulses from tlu' lower extremity and caudal portion ot the body 

 in passing from the lower to the upper end ol the primate order. 



THE NUCLEUS OF Bl RDACH 



The nucleus of Burdach likewise presiMits not a few diltieulties as evo- 

 lutional evidence in the great anthropoids. Estimated merelx u])on the 

 basis of its size, orang has the acKantage over both gorilla and chimpanzee, 

 thus indicating that the former possesses higher manual ditleri'iit iation. 1 he 



