710 THE HIGHER ANTHROPOIDS 



Such testimony as it docs produce may he particularlx fortunate il it empha- 

 sizes the need for careful scrutiny and (^reat caution in accepting the evidence 

 of evolutional structures concerning which there ma\' be any doubts 

 whatsoever. 



When the great apes are contrasted w ith the lower primates, a striking 

 fact comes to light. Mycetes exceeds in the size of its nucleus of Burdach not 

 only all of the great anthropoids, but all other primates as well. This feature 

 has been discussed in the relation of the lower to the intermediate forms. 

 Emphasis has already been laid upon the probable bearing of the high degree 

 of manual specialization consecpient upon tlu' animal's jwssession oi an 

 active prehensile tail. 



Conclusions to Be Drawn from .\ Study of the Dorsal Sensory Field 



If the conclusions to be drawn trom the relative' proportions of Burdach's 

 nucleus to the differentiation of the hand in primates are somewhat indeci- 

 sive, if they leave the tjuestion still in need of further iiuestigation, the 

 dorsal sensory field as a whole bears witness a\ hich is satisfactory and posi- 

 tive. It makes clear that in passing from the lower to the higher members 

 of the primate order there is a delinite increase m the inlliix ol sensory 

 imjjulses received Irom the proprioceptors ol the upper extremity. In other 

 words, whatever the size of the receiving nucleus in the column of Burdach, 

 the impulses which reach it trom the hand and upper extremity progressnely 

 increase in xolume. \ his progressive expansion m Burdach's column is so 

 obvious as to leax'c no room tor doubt. A dmieiisional comparison ol the 

 conduction columns m the dorsal sensor\- lield sutlices to establish this ])oint. 

 I n the lowt'r prima tt's the column ot (joII is larger than the column ot Burdach. 

 Gradually' the column ol Goll becomes less than tlu- column ol Burdach, 

 which may be understood to indicate a lallmg oil in the relatni' importance 

 of the sensory conduction system Irom tlu' hinder j>ortions ol the body as 



