THE NERVOUS SYSTEM AND CONSCIOUSNESS. 735 



tion and enlargement of the spinal-cord ; above this we see the pons 

 Varolii, and to right and left the lobes of the cerebellum which lie 

 under the posterior portions of the cerebrum. At the upper part of 

 the pons we see two stems or crura passing to the cerebrum, and serv- 

 ing to join that larger organ with the nerve-matter below. 



A little above the crura, and near the center of the mass, we see 

 what is called the op- 

 tic commissure. This 

 is simply the crossing 

 of the optic nerves 

 on their way to the 

 eyes. Directly below 

 this commissure are 

 two small rounded 

 eminences called the 

 corpora albicantia, 

 while above, on a 

 stem, is the pituitary 

 body. Beyond the 

 optic commissure lie 

 the olfactory bulbs, 

 one on each hemis- 

 phere, placed in a 

 slight depression of 

 the surface. If we 

 turn the brain over, 

 its numerous convo- 

 lutions are seen ex- 

 tending from end to 

 end, from side to side, 

 and also following 

 the lateral surfaces 

 right and left of the 

 great longitudinal 

 fissure. 



On removing a 

 horizontal piece from 

 the upper portion of 

 each hemisphere, the 

 cell - matter of the 

 surface will be found 

 to follow the differ- 

 ent windings, while the center of each convolution will be seen to be 

 made up of fibers continuous with fiber-matter in the interior of the 

 hemisphere. Should we cut deeper, we would come upon the corpus 

 callosum, the band of connection between the hemispheres ; this body is 



