FUNCTIONS OF THE BRAIN 



925 



cells (internal granular or 

 stellate layer); (5) a ' gang- 

 lionic ' layer, containing the 

 largest pyramidal cells (deep 

 large -pyramids] ; (6) a layer 

 (lamina multiformis) of 

 spindle-shaped or polymor- 

 phous cells. These layers 

 vary in their structural de- 

 tails, and especially in their 

 relative development in 

 animals of different rank in 

 the mammalian scale, in one 

 and the same animal at 

 different periods in its em- 

 bryonic and extra - uterine 

 growth, and also in different 

 parts of the cortex in an adult 

 animal of given species. The 

 region in front of the central 

 sulcus (fissure of Rolando), 

 e.g., is characterized by the 

 presence of the giant pyra- 

 mids of Betz, which give 

 origin to the pyramidal fibres 

 going to the trunk and limbs 

 (Fig. 373)- 



1 



Fig. 372. Cell-Lamination of Gyrus Postcen- 

 tralis (Campbell). A, just behind upper end 

 of fissure of Rolando; B, from the posterior 

 edge of the gyrus (intermediate postcentral 

 area of Campbell). 



Fig. 373- Cell-Lamination of Gyrus Pre- 

 centralis (Campbell). From the portion 

 of the gyrus immediately in front of the 

 central sulcus (Campbell's precentral 

 area in Figs. 375, 376). 



Fig. 374. Cell-Larnination of Gyrus 

 Precentralis (Campbell). From an- 

 terior part of the gyrus (Campbell's 

 intermediate precentral area in 

 Figs. 375. 376). 



Although the results are less definite, the work of Flechsig on the 

 time of development of the medullary sheath of the fibres in the various 

 cerebral convolutions has also contributed to our knowledge of localiza- 



