fmedt 



of the dendrites entering this superficial neuropil are impregnated. The vertical 

 superficial fibers which discharge collaterals into this neuropil probably belong 

 to the marginal optic tract (cf. fig. 5-4), though it is possible that they belong to 

 the axial optic tract or to the tractus tecto-thalamicus et hypothalamicus cru- 

 ciatus anterior after their decussation (cf. fig. 56). X 74 (cciii, 3-1-6). 



Fig. 27 Detail of a section through the ventral part of the thalamus at the 

 level of the middle of the cMasma ridge (cf. fig. 3, which is taken from about the 

 same place). Drawn from the same series as figure 25. The fibers of the lat- 

 eral forebrain bundle are not impregnated, but a part of those of the medial 

 bundle are shown (f.med.t.). At this level the chiasma ridge is filled with a dense 

 neuropil composed chiefly of contorted axons of the tractus thalamo-hypothal- 

 amicus et peduncularis cruciatus mingled with dendrites of the neurons lying 

 farther dorsally. The section is too thin to reveal the sources of all the den- 

 drites, but the indications are that they come from both the hypothalamus and 

 the pars ventralis thalami. Those from the latter source are related more 

 especially with the tractus tecto-thalamicus et hypothalamicus cruciatus. X 60 

 (cvc, 3-1-8). 



319 



