104 



THE LOWER PRIMATES 



tarsius, namely, the turning of its Iiead completely around so that it can look 

 backward as well as to the front. The animal moves its head rather than its 

 eyes in its visual pursuit of objects. This requires a highly speciahzed cervical 



FIG. 51. TARSIUS SPECTRUM. LEVEL OF THE PYRAMIDAL DECUSSATION. 



CB, Column of Burdach; cen, Central Gray Matter; CG, Column of Goll; dt, Deiterso-spinal Tract; fle, 

 Dorsal Spinocerebellar Tract; cow, Ventral Spinocerebellar Tract; nb. Nucleus of Burdach; nr. Nucleus of 

 Rolando; py. Pyramid; pyx. Pyramidal Decussation; ref, Reticular Formation; rst. Rubrospinal Tract; 

 SPT, Spinothalamic Tract; trd, Descending Trigeminal Tract; ven, Ventral Gray Matter. [Accession No. 

 210. Section 65. Actual Size 4X3 mm.] 



musculature, which no doubt determines the prominent spinal accessory 

 feature in this region of the brain stem. 



