THE CORTICAL GRAY MATTER. 



203 



in the adult human brain. The cortex of this whole region is 

 so rudimentary or vestigial as to require but brief description. 

 The plexiform layer may be identified. The whole gray substance 

 beneath that is occupied by scattered pyramids of medium size, 

 separated by strands of fibers belonging to the olfactory tract and, 

 perhaps, to the cingulum. 



Central core of 

 ependymal cells 



Fibers to C: 

 tract. 



5. S. granulosum 



4. S. cellulare 

 3. S. reticulare 



2. S. glomeru- 

 losurn 



i. S. nervosum 



Nasal mucous 

 membrane 



Olfactory cell- 

 bodies 



Fig. 63. Chief elements of the olfactory bulb. (Gordinier after Van Gehuchten.} 



The cortex of the gyrus cinguli (Fig. 28) is characterized by 

 an entire absence of large fibers and large cells, by an oblique 

 and irregular direction of the pyramids and by a most remarkable 

 color affinity possessed by the deep cells. There are only four 

 cell layers, (i) The plexiform presents a faint stratum zonale, 

 but nothing characteristic. (2) The layer of small pyramids 



