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THE NERVOUS SYSTEM 



ment is that in which the cortex is divided into four layers. The outermost, 

 or superficial, known as the molecular layer, contains relatively few cells. 

 It is composed of neuroglia tissue, embedded in which are a number of cells 

 of the Cajal types, which have just been described. There are also in this 

 layer many neuroglia cells. In the superficial part of the layer of some areas 



FIG. 395. The Principal Constituent Elements of the Gray Cortical Layer of the Anterior 

 Cerebrum. (After Ramon y Cajal.) 



of the cortex are many tangential fibers. The second layer is composed of 

 small pyramidal cells. In parts of the brain there are here interposed 

 what are known as the vertical fusiform cells. The third layer is composed 

 of large pyramidal cells, in which, however, one also sees many small py- 

 ramidal cells. The fourth layer is composed of the fusiform and polymorphous 

 cells, beneath which is the white substance. This arrangement is shown 



