102 NAOKI SUGITA 
TABLE 9—Continued 
CORRECTION- PERCENT- 
OBSERVED c TED 
COEFFICIENT | DIS AGE OF 
AIN 
GROUP | erat ; ; | ek 
Areniat Area of | W.D The Agoavot Area of DA, 
cortex total in fresh same on cortex total nanos 
i section brain slide ; section = 
grams mm. mm 2 mm. mm. mm.2 mm .2 per cent 
IN PXGVA CH S25) | or Os| i S2eon |e leeA Dae lORSON i =e2956 63.7 47 
BY || dbase || EON, S.74 less) || ALL AAD ADS 61.0 49 
1.829 | 17.0 | 35.8 1.32? 29.6 62.4 48 
N XIX b)| 1.962) 166) 36.6) 14:60 11.20) 2873 62.3 44 
a| 1.981 15.3 | 32.9 | 18.95 10.30 | 28.1 60.5 47 
LOTSA Pe LOLOR S48 Uk 33)" 28.2 61.4 46 
NXXe| 2.015 | 14.6] 38.1 14.30} 10.20) 28.7 65.2 44 
a |) 2.089 |" 1527 | 35-5) || 14250" 10595) 2726 62.3 44 
2.052 | 15.2| 34.3 1.36? 28.2 63.8 44 
Ni XOX gi) 022156) oie 35.2 1A Coy) LOE AON 28.0 67.0 43 
ds| 2-187, |) 15c3F | 3460 15.05 | 10.70 | 30.3 67 .4 45 
2.172 | 15.2 | 34.6 il Gh 29.5 67.2 44 
\ 
section may be calculated by the following formula, in which 
T., denotes the average cortical thickness in the sagittal section. 
Ee EEX TS 20 (L. F and 7’, in millimeters) 
The corresponding coefficient was found to be 1.22 in the 
Albino brains weighing more than 0.5 gram (table 4), but 1.20 
for brains weighing more than 1.3 grams (Groups XIII-XX). 
The coefficients in the two forms may therefore be considered 
similar, that for the Albino being a trifle the larger. 
If comparison is made between the absolute values of the cor- 
tical areas in the sagittal sections of the Norway and the Albino 
brains of like weight, no great difference appears (table 12). In 
the pair of Groups N XI and XI, the Norway is 10 per cent 
smaller in the area. This may be explained by the fact that the 
Norway brain weighing 1.16 grams is in a younger stage of cor- 
tical development, as compared with the Albino brain of like 
weight, the cortex of which is already provided with nearly all 
its nerve elements. But, in the pairs of Groups N XIII-XIII 
