TROGLODYTES GORILLA 



683 



LE\EL OF THE OPTIC CHIASM (EIG. 3IO) 



At this level a marked ehan<i;i' in the outline of the section is determined 

 by the appearance of tlie third ventricle i \' 3 ) and the two optic thalami. 



r-TG. 310. GOKILI.A. LEVEL OF THE OPTIC CHIASM. 



ciN, Internal Capsule; cph, Corpus Hypothaiamicuni; rni", Desci-ndin({ Pillars iif tin- Fornix; i ok, Fornix: 

 GLP, Globus Palliclus; nca, Caudate Nucleus; nl. Lateral Nucleus of the Thalamus; nld, m.i. Internal Liiteral 

 Nucleus of the Thalamus; nm, Middle Nucleus of the Thalamus; oi'X, Optic Chiasm; PtT, Putamen; vq. 

 Fasciculus of Vicq D'Azyr; vj, Third Wntricle. [Accession No. J. D. Section toiq. Actual Size 4, X 24 mm.! 



In llu' \entriciilar lloor an- the decussating fibers in the optic |xith\va\ form- 

 ing the optic chiasm (0])\). Superposed abo^•e the optic fibers is a small 

 specialized bundle of libers constituting tlie narrow sujjia-optic commis- 

 sure of Meynert. The two optic thalami are separated from the corjius 

 striatum GIpi by the interposition of the dense mass of myelinated 

 libers forming the internal capsule (Cin). This secti<jn illustrates the 



