22 NAOKI SUGITA 
TABLE 5—Concluded 
THICKNESS OF THE CORTEX 
COEFFICIENT 
c (FRONTAL SECTION) 
BRAIN WEIGHT BRAIN 
J WEIG : ; 
GROUP EIGHT | Diam.W.D eee 
on | Gavelida Loc Wii Loc. VII | Loc. VIII | Average 
fresh brain 
grams mm. mm. mm. mm. mm. mm. 
N XIX b} 1.962 14.60 11.60 2.08 2.28 1.68 2.01 
Bele 981 13.95 10.80 2.04 2.21 AZ, 1.99 
1.972 1.26 2.06 2.95 1.70 | 2.00 
NXXe]/ 2.015 14.30 10.50 2.14 2.32 173 2.06 
a| 2.089 14.50 11.20 1.80 2.08 1.66 1.85 
2.052 WSS 129% 2.20 1.70 1.96 
NXXIg| 2.156 14.75 11.10 2.03 2 94 1.69 1.99 
ail) 2187 15.05 10.80 2.19 2.54 1377) Ae oatz 
2.172 1.36 2.11 2.39 1.73 | 2.08 
N XXII 
N XXIII 
frontal sections. Chart 6 does the same for localities IX and XIII 
with the average of localities [X to XIII in the horizontal sec- 
tions. Charts 3, 5 and 7 show the average values of the cortical 
thickness in the sagittal, frontal and horizontal sections, for each 
brain weight group. Further, on each chart is shown the change 
in thickness at each one of the localities measured in that 
section. 
Chart 8 is based on table 7 and shows the general average (cor- 
rected) thickness of the cerebral cortex of the Norway rat accord- 
ing to the brain weight and also the average thickness in each of 
the sections. 
VI. DISCUSSION 
The relations existing between each of the several localities 
measured in this study of the Norway are quite similar to the 
relations found in the cerebral cortex of the albino rat. Individual 
variations appear, but these are no higher than +6 per cent, 
compared with the average values of the group. No sex differ- 
