TrtTh 



changed. The tractus bulbo-tectalis (tr.b.f.) is spreading out and ending by 

 free arborizations in the nucleus posterior tecti (nuc.p.t.). Descending from 

 the nucleus posterior toward the cerebral peduncle is a compact fascicle be- 

 longing to the superficial tecto-peduncular system, the tractus tecto-peduncu- 

 laris posterior (tr.t.pcd.post.). At the boundary between thalamus and mid- 

 brain are fibers of the tractus thalamo-peduncularis dorsal is superficialis (tr. 

 th.p.d.s.) which descend from the pars intercalaris diencephali to the cerebral 

 peduncle in the vicinity of the area lateralis tegmenti (cf. fig. 53). The marginal 

 optic tract (tr.op.) is seen crossing the thalamus, and farther ventrally the so- 

 called basal optic bundle {fr.op.b.) traverses the extreme lateral border of the 

 hypothalamus. X 30 (U, 25). 



Fig. 53 From the same series two sections farther medialward. The mar- 

 ginal optic tract {tr.op). is heavily impregnated; mingled with these fibers may 

 be some of the tractus tecto-thalamicus et hypothalamicus cruciatus anterior. 

 Terminals of the tractus bulbo-tectalis ilr.h.t.) are still seen in ihe nucleus pos- 

 terior tecti {nuc.p.i.). The acoustico-lateral lemniscus (Zm.) reaches the remain- 

 der of the tectum. X 30 (U, 27). 



339 



