158 



BRAINS OF RATS AND MEN 



relatively and absolutely, of the neopallium and its 

 more complex structure. The rat's cortex, however, is 

 also of very primitive type; it is far less differentiated 

 than that of the rabbit and some other rodents. Fig- 

 ure 39 is a diagram of the typical arrangement of the 







I. Lamina zonalis. 



III. Lamina pyramidalis. 



IV. Lamina granulans interna. 



V. Lamina ganglionaris. 



Ectal sublayer 

 "1 Ental sublayer. 



Lamina multiformis. 



Fig. 39. — Diagram of the typical cell lamination of the cerebral 

 cortex of the albino rat. After Sugita (1917). 



cellular layers of this cortex. This arrangement dif- 

 fers in various parts of the cortex in the thickness of 

 the layers and the sizes, shapes, and grouping of the 

 nerve cells within them. 



Microscopical examination of the cortex of the rat, 

 mouse, and other small rodents has been made by a 

 number of our most competent neurological workers. 

 The greater part of Ramon y Cajal's monumental re- 



