100 NAOKI SUGITA 
TABLE 8—Continued 
C ORRECTION-COEFFICIENT 
OBSERVED CORRECTED 
GROUP BRAIN WEIGHT AREA AREA 
OF CORTEX L.F The same OF CORTEX 
on fresh brain on slide 
“ grams mm.? mm. : mm. mm.2 
N XIX b 1.962 19.9 14.70 TL 4s) 34.1. 
a 1.981 19.5 14.40 11.00 3520 
1.972 ORT ihaesike2 33.8 
N XX ¢ 2.015 20.6 14.55 11.30 34.2 
a 2.089 20.7 14.95 11.80 33.3 
2.052 20.7 1.28? 8358 
N XXI ¢g 2.156 21.1 N55 11s) 11.90 34.2 
d PR MC 20.2 15.30 | 11.50 35.7 
2.172 20 .7 1.307 35.0 
N XXII 
N XXIII a 2.345 22.4 14.50 11550 Bian 
2.3845 22.4 1.267 85.7 
N. The area of the cortex in the sagittal section. Norway rat 
compared with the Albino 
Table 11 shows the relations between the cortical area in the 
sagittal section and the longitudinal diameter of the cerebrum 
(L. Ff). Column B gives the average brain weight by groups, 
column C the average area of the cortex in the sagittal section, 
column D the average cortical thickness in the sagittal section 
(7), column F the longitudinal diameter of the cerebrum (L. F), 
all of these being the corrected values. In column FE the value 
C'/D or relative length of the long side, when the cortical area 
-was reduced to a rectangle with the short side equal to the cor- 
tical thickness, appears. As shown in column G as E/F. these 
computed lengths show similar ratios when divided by the actual 
diameters L.F (column F), that is, 1.16 to 1.24 or on the average 
1.20 for Groups N XI-N XXIII, but 1.19 for Groups N XIII- 
N XX. If necessary, therefore, the cortical area in the sagittal 
