204 NAOKI SUGITA 
Cortical area (mm.’) in sagittal section 
Cortical thickness (mm.) in the same 
Cortical area (mm.”) in frontal section 
Cortical thickness (mm.) in the same 
And the computed volume of the cortex should be obtained 
simply by the following formula: 
L.F x W.D X T (all in millimeters), (3) 
where T gives the general average thickness of the cerebral cortex 
of the same brain. 
As shown in table 9, which has been condensed from table 9 a 
(unpublished) for each individual, the constant ratios obtained 
by the above formulas (1) and (2) fall between 1.10 and 1.29 for 
the sagittal sections and between 0.80 and 0.95 for the frontal 
sections, throughout both the underfed and the control groups. 
The averages of the ratios for the sagittal and frontal sections of 
the underfed are, respectively, 1.18 and 0.88, and those of the 
controls are, respectively, 1.20 and 0.88. I have previously 
given the figures 1.22 and 0.91, respectively, as these ratios of the 
standard albino rat brains weighing more than 0.5 gram. So 
it may be assumed that the ratios are nearly the same in both the 
underfed and the controls; slight differences in the underfed 
from the standard may be regarded as due to the facts that the 
cerebrum of the underfed is sightly more elongated and the cor- 
tical thickness is somewhat greater than in the standard. As 
the product of the coefficients in the underfed (1.18 x 0.88) falls 
somewhat lower than that in the standard (1.22 x 0.91), the 
results of L.F x W.D x T should be about 5 per cent higher in 
the underfed than in the standard. 
The relative volumes of the cortex, obtained by the formula (3), 
are computed and given in table 11 (without any special cor- 
rection), compared with the corresponding standard values for 
brains of the same age, instead of for brains of the same weight. 
The relative volume of the cortex in the underfed brains, which 
are considerably retarded in total weight development, is greater 
than for the standard brains of the same weight, which are neces- 
sarily younger and less developed as regards the cortical elements 
than the underfed brains of like weight. 
+ L.F (mm.) = constant (1) 
+W.D(mm.) =constant (2) 
