18 NAOKI SUGITA 
as directly observed, and without correction and also the average 
values for the sagittal, frontal and horizontal sections, according 
to the increase of the brain weight. 
V. CORRECTED DATA PRESENTED IN TABLES AND CHARTS 
Using the detailed observed values which were all carefully 
tabulated, although they have not been published, a series of 
mm. 
24; ———- 
il | 
= al 
| 
| 
dle hel 
|_| i | 
| eee 
| 
| 
19 20 21 22 23 gs 
ore 
| 
| 
| 
| 
| 
| 
fo i 12 43 14 15 16 IT 18 
Chart 1 Giving the average thickness of the cortex on slide (not corrected)’ 
’ . in the sagittal, frontal and horizontal sections and the general average thickness 
on brain weight group in the Norway rat. Based on table 3. -—--—S Average 
thickness of the cortex in sagittal section. Measuredon slide. —-——-F Average 
thickness of the cortex in frontal section. Measured onslide. - - - - - H Average 
thickness of the cortex in horizontal section. Measured onslide. *———*A Gen- 
eral average thickness of the cortex of three kinds of sections. Measured on slide. 
correction-coefficients, obtained in exactly the same manner as 
for the albino rat, were found and applied to the observations 
on the Norway cortex. The corrected values are those entered 
in tables 4,5 and 6. The tables also contain in each case the 
measurements from which the correction-coefficient was obtained 
and for each brain weight group the average value of the cor- 
rection-coefficient for that group. 
Table 7 shows the corrected values for the average thickness of 
the cortex, obtained in the same way as were the uncorrected 
