ANATOMY AND PHYSIOLOGY OF THE BKAIN. 415 



callosum) consisting of fibres passing between the hemi- 

 spheres. It is only about two-thirds the length of the 

 hemispheres, and approaches nearer the anterior than the 

 posterior extremity. Its function seems to be the connect- 

 ing of the two hemispheres in intellectual acts. 



If we cut off one of the hemispheres just above the level 

 of the corpus callosum, and make a downward incision to 

 one side of the latter, we open into the lateral ventricle of 

 that side. The principal objects to be seen on its floor 

 are : 1st, Toward the outer and anterior part of the 

 ventricle a pear-shaped body (corpus striatum, 4 4) formed 



Fig. 215. Transverse section of the cerebrum, showing the lateral ventricles. 1 1, Hip- 

 pocampi majores; 22, teniaa semicirculares ; 33, choroid plexus; 44, corpora striata; 

 5, portion of the fornix. 



of grey matter externally and white internally. This is 

 connected with the substance of the brain and the optic 

 thalamits. The latter is a considerable eminence at 

 the posterior and inner part of the ventricle, where it is 

 covered by the choroid plexus (3 3), an intricate network of 



