GROWTH OF THE CEREBRAL CORTEX 63 
The diameter L. F in fresh cerebrum 
The diameter L. F' on the slide 
the correction-coefficient was determined. The value for the 
area obtained by the (first) direct measurement from the slide 
was then corrected to the corresponding value for the fresh 
condition of the material, by multiplying by the square of the 
correction-coefficient. The corrected values thus obtained are 
given in the last column of table 1. 
The values for the cortical areas in the respective sagittal 
sections of each individual were then grouped according to the 
Correction-coefficient = 
Fig. 1 Showing, by shading, the cortical area measured on the sagittal sec- 
tion of the albino rat brain. The anterior borderline ((a—a’) is formed by a pro- 
longation of the line bounding the dorsal surface of the olfactory bulb. The 
posterior borderline (p—p’) is drawn at the point where the ganglionic layer goes 
over abruptly to the ganglion cell band in the cornu Ammonis. 
brain weight, into twenty groups, as in the other studies of this 
series, and the average value for each group wasfound. The aver- 
age areas of the cortex in the sagittal section for each group 
(table 1) were plotted in chart 1 (graph s), which shows the in- 
crease in area according to the increase in brain weight. 
B. Area of the cortex in the frontal section 
The frontal section (fig. 2) was cut in the plane passing through 
approximately the middle point of the mesial surface of the 
