ii6 



THE LOWER PRIMATES 



longitudinal fasciculus (PL) has been augmented by the addition of 

 fibers from Deiters' nucleus, whose course may be traced inward and back- 

 ward from this nucleus. Some of the caudal fibers of the vestibular division 



FIG. j6. TARSIUS SPECTRUM. LEVEL OF CAUDAL EXTREMITY OF 

 TRAPEZOID BODY. 



COCH, Cochlear Fibers; ctr, Trapezoid Body; ctt, Central Tegmental Tract; dt, Deiterso-spinal Tract; 

 cow. Ventral Spinocerebellar Tract; icp. Inferior Cerebellar Peduncle; mf, Mesial Fillet; nd, Deitersal Area; 

 n8. Auditory Nerve; nfs. Genu of Facial Nerve; nr, Nucleus of Rolando; nsc, Nucleus of Schwalbe; pd, 

 Predorsal Bundle; PL, Posterior Longitudinal Fasciculus; py, Pyramid; ref. Reticular Formation; rst. 

 Rubrospinal Tract; so, Superior Olive; spt, Spinothalamic Tract; trd. Descending Trigeminal Tract; tub, 

 Tuberculum Acusticum. [Accession No. 210. Section 153. Actual Size 7X3 mm.] 



of the eighth nerve pass through the descending trigeminal tract and the 

 substantia gelatinosa to enter Deiters' nucleus. A large nuclear structure on 

 the periphery of the reticular formation gives rise to the first portion of the 

 facial nerve. This is the nucleus facialis (Nf). The fibers arising in it 

 pass backward and inward to\\ard the lloor of the fourth ventricle in the 

 form of a heavy spray. This nucleus in tarsius is nearer the periphery of 

 the section than in any of the other primates and the fibers constituting the 

 first portion of the facial nerve are coarser than observed in other species. 



