BASE OF BEAIN, OPTIC NEBVE, AND CORPOBA QUADEIGEMINA. 391 



The crura of the fornix are now no longer seen, but there lies under the corpus 

 callosum the broad plate of the psalterium, on the edges of which lie the fimbriae. 

 Through an interchange of fibers in this territory arise the true fornix columns. Far 

 below is to be noted the origin of the fimbria from the medullary substance of the 

 hippocampal cortex, and its relation to the inferior horn of the ventricle. 



We will now at once trace the optic radiation farther backward until 

 within the apex of the occipital lobe, so that a clear idea may be gained of 



Gyrus fuai- 

 formis 



Fig. 187. 



it as a whole, for this reason I here demonstrate a section in Fig. 186 that 

 is located about three-fourths of a centimeter behind that of Pig. 179. 



The anterior corpora quadrigemina are exactly halved. Away from the cut 

 surface of the crus cerebri, the pulvinar and the corpora geniculata are seen in the 

 interior of the section on the right. The development of the pes pedunculi from the 

 capsula interna becomes especially clear upon comparison of this section with those 

 made farther anteriorly, because the egress of the peduncles from the base of the 

 brain is so plainly visible here. 



