NERVOUS SYSTEM 



83 



weight of 1.154 grams, equivalent to 20 days of age — or the time 

 of weaning. 



Number of cells in two layers of the cerebral cortex {computed). 

 Using two layers, the lamina pyramidalis and the lamina 

 ganglionaris, in a selected locality VII Figure 9 (Sugita, '18 b) 

 determined the number of cejls in a unit volume of the cortex 

 (one-thousandth of a cubic millimeter). 



Fig. 8 Diagram of the horizontal section, from the albino rat brain weighing 

 1.5 grams, indicating the position of the localities measured on the section and 

 the cortical cell-lamination. //' and ss' show respectively the levels from which 

 the frontal and the sagittal sections were taken. The lines PP', QQ', RR', 

 SS', TT', UU', WW, X' and YY' indicate the borders of areas which show dif- 

 ferences of cell-lamination and V indicates the rhinal fissure. 



