GROWTH OF THE CEREBRAL CORTEX 537 



V. NOTES ON THE CORTEX OF THE NEWBORN ALBINO RAT BRAIN 



In the foregoing chapter I have given a general description of 

 the lamination of the mature cerebral cortex of the albino rat. 

 But, in the case of the younger animals, especially at birth, the 

 appearance of the sections is, of course, not the same, since the 

 cortex is in an earlier stage of development. Figure 7 shows a 

 general picture of the sagittal section of the newborn rat brain 



Fig. 7 Diagram showing the cortical cell-lamination of' the newborn albino 

 rat brain, which weighs 0.2 gram. Crosses (X-X) show the location from which 

 figure 8 was taken. 



(based on Rat. No. II a, brain weight 0.2132 grams), and figure 

 8 shows an enlarged, diagrammatic picture of the cell-lamination 

 from the part marked with two crosses in figure 7, correspond- 

 ing to locality II (fig. 2). In comparison with figure 9, which 

 shows the corresponding part of the cerebral cortex in the sagittal 

 section of the mature rat brain, locality II (fig. 2), the newborn 

 cortex presents an appearance of more complexity, especially in 

 the regions adjoining to the ventricular walls. The cells which 



