HYLOBATES HOOLOCK, THE GIBBON 429 



The general size of the nucleus of Blumenau ( N B I ) is suggestive, as 

 in other levels, of the degree to which the forelimb and hand have developed. 

 Emphasis has been laid on the fact that the relatively poor development of 



FIG. 202. GIBBON. LIALl IHKOLGH THE MIDDLE OF THE INFERIOR OLI\ E. 



AMB, Nucleus Ambiguus; do. Dorsal Accessory Olive; dt, Deiterso-spinal Tract; gow. Ventral Spinocerebellar 

 Tract; icp. Inferior Cerebellar Peduncle; lO, Inferior Olive; mf. Mesial Fillet; nbl. Nucleus of Blumenau; 

 NFS, Nucleus Fasciculus Solitarius; nhv. Hypoglossal Nucleus; nr, Nucleus of Rolando; nvd. Dorsal Vagal 

 Nucleus; nig. Tenth Cranial Nerve; ni2, Twelfth or Hypoglossal Nerve; pd, Predorsal Bundle; pl, Posterior 

 Longitudinal Fasciculus; pv. Pyramid; ref, Reticular Formation; rst. Rubrospinal Tract; spt. Spinothala- 

 mic Tract; trd. Descending Trigeminal Tract; \o. Ventral Accessory Olive. [Accession No. 141. Section 131. 

 Actual Size 14 X 8 mm.] 



the hindlimb in gibbon and the high degree of proficiency attained by the 

 upper extremity and hand, especially for the purposes of its fleet locomotion, 

 give marked structural preponderance to the nucleus of Blumenau. The 

 prominence of the inferior oIi\ary nucleus compared with the other forms 

 may also be in direct relation with the Ilight-Iike locomotion ol the animal 



