184 THE CEREBRUM. 



and olfactory regions (Fig. 58). Though Dr. Campbell's division 

 of the cortex into seven layers of cells is complicated, it is similar 

 to CajaPs description and I think it entirely worthy of general 

 adoption and shall follow it in this work. It is to be regretted 

 that the fiber and the cell layers have not been more satisfactorily 

 correlated, as this would assist in determining function. Dr. 

 Arthur W. Campbell gives the layers as follows: 



First, the layers of cells : 



1. The plexiform or molecular layer. 



2. The layer of small pyramids. 



3. The layer of medium-sized pyramids. 



4. The external layer of large pyramids. 



5. The layer of stellate or polymorphous cells. 



6. The internal layer of large pyramids. 



7. The layer of fusiform cells. 



Second, the fiber zones : 



1. The fiberless layer, or neuroglia zone. 



2. The zonal layer, stratum zonale. 



3. The supraradiary zone. 



4. The baillargic zone, line of baillarger. 



5. The radiary zone. 



6. The felt- work of Kaes. 



i. The plexiform layer has next the surface a fiberless zone of 

 neuroglia, on account of which it is often called the neuroglia- 

 layer. Underneath the neuroglia is a more or less dense plexus 

 of nerve fibers, constituting the stratum zonale; and then an area 

 of sparsely scattered fibers that belongs to the supraradiary zone. 

 Scattered here and there in the zonal and supraradiary regions 

 of the plexiform layer are small stellate cell-bodies, four or six 

 microns in diameter, belonging to the types of Golgi and Cajal, 

 whose dendrites and whose double or triple axones ramify hi the 

 stratum zonale, some near the cell-body and others at a consider- 

 able distance from it. The stratum zonale also contains dendritic 

 processes from subjacent laminae, the T-branched axones of 

 Martinotti's cells, and, perhaps, the end-tufts of incoming fibers 



