PLATE III 



Fig. I. — The left hemisphere of the brain of a chronic lunatic who has become grossly 



demented. 



Observe the broad deep fissures caused by the wasting of the grey matter of the cortex, particularly of the 

 frontal lobes. The convolutions are shrivelled, and a microscopic examination of them would show 

 chiefly a destruction of the cells and fibres constituting their microscopic architecture. 



Fig 2.— Diagrammatic illustration after Brodmann of the cell and fibre architecture of 



the cerebral cortex. 



There are six layers of cells and six layers of fibres. To the left are exhibited the different types of cells 

 in the successive layers stained by the silver method, which only picks out a few cells. In the next 

 column all the cells are stained by the Nisol method. Number IV layer consists of small granules, and 

 above this are three layers of pyramids. Below the granules are larger pyramids in the layer V. 

 Beneath this in the sixth layer are multiform cells. In the next column is represented the fibre 

 structure; the vertical fibres are projection' fibres carrying impulses afferent and efferent to and from 

 the brain cortex. The layer of pyramids above the granules is especially connected with the function 

 of associative memory. The horizontal systems of fibres are association systems. 



300] 



