20 NAOKI SUGITA 
TABLE 4—Continued 
CORRECTION- THICKNESS OF THE CORTEX 
COEFFICIENT (SAGITTAL SECTION) 
BRAIN WEIGHT | BRAIN 
GROUP WEIGHT | Diam. Di 
Dak 1am. Aver- 
oni ireshile ee: Loc. I | Loc. II |fLoc. III | Loc. IV | Loc. V 
brain on slide a 
grams mm. mm. mm. mm, mm. mm. mm, mm, 
N XIX b | 1.962 | 14.70 | 11.50 2.98 2.12 1.97 1.54 | 1.46 | 2.01 
a | 1.981 | 14.40 | 11.50 2.83 2.08 7s 1.54 | 1.44 | 1.93 
1.972 1.26 2.91 2.10 1.86 igh |) IAS |) Oi 
N XX c | 2.015 | 14.55 | 11.50 | 2.86 | 2.00 | 1.81 | 1.55 | 1.43 | 1.93 
a | 2.089 | 14.95 | 12.00! 2.75] 1.93] 1.671 1.341 1.30 | 1.80 
2.052 1.25: 2.81 1 97 A ELON dL Kova els ia 
N XXI g | 2.156 | 15.15 | 11.90 | 3.01 | 2.15 | 1.82) 1.58] 1.40") 199 
d| 2.187 | 15.30 | 11.50 | 2.94] 2.09] 1.85! 1.60 | 1.41 | 1.98 
mie, 1230 2.98 CPA 1.84 ANS) || lel |) 2 
N XXII ] 
N XXII a | 2.345 | 14.50 | 12.50 | 2.74| 2.07 | 1.75| 1.38 | 1.93 | 1.86 
2.3845 LUG: 2.74 2.07 US ih isxey || Il SoS) || JL SIH 
values shown in table 3. This table (table 7) serves as a stand- 
ard for discussing the actual thickness of the fresh cortex of the 
Norway rat. The average thickness in the adult Norway rat is 
2.06 mm., as obtained by averaging the thicknesses of the cortex 
in Groups N XV—-N XXIII, in which stages the cortex may be 
considered to have reached its full thickness. 
Charts 2 to 7 show graphically the data given in tables 4 to 6 
respectively, and chart 8, which is based on table 7 giving the 
average values, presents a general picture of the growth changes 
in the cortex according to brain weight. 
Charts 2, 4 and 6 show the individual determinations for the 
thickness of the cortex in the sagittal, frontal and horizontal sec- 
tions, respectively, plotted according to the brain weight. 
Chart 2 gives the individual records for locality I and locality V 
with the average for all localities from I to V in the sagittal 
sections. In a like manner, chart 4 gives the values for localities 
VJT and VIII with the DSS of localities VI to VIII for the 
