RECONSTRICTION OF HUMAN 



839 



compIc\it\ and si/.c of the nUw has paralleled tlu' emergence of tlu' hand as 

 an lnd(.'|)t'ndent nuMiiIxT lor the exploration of the cmironnu'iit. 1 his ini|)rove- 

 nu'iit in nianual de\terit\ in eon jiinet ion with the perleetmn ol hmoeular 



ftETlCUL* 



FK;. 358. LATERAL SURFACE OF CM \\ \L\TTER OF BRAIN STEM, HOMO SAPIENS. 

 Key to Diagram, arc. nlc, Arcifoim Nuckus; (eis. gbav matter, Cintrnl Gmy Mattir; <;ociil. com. 

 Cochlear Compli-x; inf. coll.. Interior Colliculus; inferior olivary nuc, Inferior Olivary Nucleus; ret. 

 FORM., Reticular Formation; sub. nigra. Substantia Nigra; sup. coll., Superior (!c>lliciilus; vest, comf.. 

 Vestibular C~ompIex; 3rd nerve M'C., Nucleus of the Oculomotor Nerve. 



vision mav he explained b\- the critical exercise of the visual Junction in the 

 guidaiux' of the hand and arm. One other feature w hich deser\i's mention is 

 the marked increase in the clearness and delmition exinced l)\ the \ari(nis 

 channels, w hich the lon^^ w hiti' lihi'r tracts ha\x' ])roduccd throui^h tlu' reticu- 

 lar formation and tln' otlu'r i^iortions of the gray matter ol tlu' stem. These 

 channels presc-nt a greater sharpness and (U'linition of outline than that seen 

 in the preceding members ol this group. 



The Dorsal Medlllari' Nuclei 

 In the lowfst |)art of the rc-construction the dorsal medullary nuclei 

 appear alrcad\ fairly wi-ll diA ciopi'd. l"lu' nucli'us ot the column ol Coll, 



