TeLEN'CEPHALOX — ^XON-OLFACTORY PORTIOXS 113 



The appearance of the layers in a typical region of the 

 cortex of the rat may be summed up as follows. The super- 

 ficial layer, the lamina zonalis (I.), contains only a few 

 scattered glia cells. The lamina pyramidalis (III.) below 

 it is made up of typical, deeply-staining, pyramidal cells, 

 rather closely packed together. Under this layer, the lamina 

 granularis interna (IV.) appears as a band of crowded, deeply- 

 staining, small granules, somew^hat resembling glia cells. 

 Beneath this again Is the lamina gangllonarls (\'.), which 

 contains somewhat scattered, large-sized, deeply-staining py- 

 ramids. Finally, the deepest layer consists of a broad zone 

 of polymorphous cells, the lamina multiformis (VI.). These 

 are represented on the left side of PI. XXVII. 



The laminae differ considerably in details of their structure 

 and relative development in different regions of the cerebral 

 cortex, one sometimes even appearing distinctly subdivided, 

 or again one disappearing entirely at certain points. Thus 

 It has been found possible to map out a considerable number 

 of areas In the neocortex, each with a distinct histological 

 structure and, presumably, with a more or less distinct 

 functional significance. Homologous areas can, moreover, 

 be recognized In the various groups of mammals. Further, 

 the principal areas have been shown to have definite differences 



Fig. 10. Cortical localization in the wild Norway rat. Diagrams of 

 the lateral, medial and dorsal surfaces, from Fortuyn. 



Fortuyns area. Brodmanns term. 



f, f Regio praecentralis. 



j, n Regio parietalis. 



w Regio occipitalis. 



k Regio insularis. 



p, X -. Regio temporalis. 



c Regio cingularis. 



z, z", z'" Regio retrosplenialis. 



r', s Regio hippocampica. 



h, h" Regio olfactoria. 



Regio postcentralis is represented in the anterior part of area j. 



