SUMMAR\ OF STRUCTURES 



709 



apparent mcniisistciK'irs ol such a xicw arc cnicIciU at oncx'. In maintain 

 that the orang-outang- has a niori' highl\ ch'Hrrrntlatrd IkuuI tlian citlirr the 

 gorilla or the ehnii|janzt'e seems untenable by the criteria of our present 

 knowledge. Ne\ertheless, the dillerences obtauied by actual measurenu'nts 

 are sufliciently striking to make this supposition a strong probabilit\. I-Orthc 

 time, at least, it may be w iser to accept the conclusion forced b\ this relati\'e 

 mensuration ol the nucleus ol Burdach and seek further light which mav 

 uphold or disprove it. The planimetric and longitudinal coellicients ol' the 

 nucleus ol Burdach in the great anthropoids are gi\'en in tlu' following 

 tabukition : 



\\ hen compared with the mtcrmediatt' primates, the nucleus of Burdach 

 in the great apes again shows a somewhat surprising ec[uality. In fact, the 

 size of this nucleus in macacus closely approaches that ol the orang, and 

 actually exceeds the dimensions ol the nucleus in the chim|)anzct' and the 

 gorilla. The signillcancc to be attached to this comparati\e mensuration 

 points to the fact that in at least one ol tlu' intermediate primates, inlhu'iices 

 are ojjerative in the dillerentiation ol tht' upper extremity which iec|uire a 

 high degree ol |)roprioci-pt i\ t- re|)rescntation in tlu' nucleus ol Burdach. 

 The |)rincipal mlluence underlying this (k'\ elopmi'iit is tlu' specialization of 

 the hand. Extreme degrees ol such specialization ma\ oct'ur along sc\eral 

 divergent !iiu-s. The e\i(k'nct', thcrclore, allordcd by the nucleus of Burdach 

 as bearing upon manual dillerentiation must be weighed most critically. 



