246 NAOKI SUGITA 
TABLE 2 
A comparison of the thicknesses Of the cerebral cortex at several corresponding 
localities in the albino rat and in the mouse. The data for the albino rat were taken 
from table 11 in my previous paper (Sugita, ’17 a, p. 578) and the data for the 
mouse were taken from a paper by Isenschmid (11). The order of increasing 
thickness is the same in both animals 
ALBINO RAT MOUSE 
Average Average 
Locality _| thickness of ICorresponding locality | Thigkness of cortes at | thickness of 
locality locality 
mm. mm. mm. 
V and XIII 24. c 0.50 0.50 
IV 1.42 d 0.53 0.53 
XIT and VIII 1.67 e and i 0.65 and 0.44 0.55 
III and XI 1.91 aande 0.73 and 0.65 0.69 
VI 2.01 1 (corner) 0.78 0.78 
II and X 2.03 k and b 0.81 and 0.86 0.84 
VII 2.29 b 0.86 0.86 
I and IX 2.99 frontal pole 1.00 1.00 
IAVELAP Cs se la 1.94 IANET AR Cb acm Ree eT eee 0.72 
for the Albino are so entered that the cortical thicknesses at the 
corresponding localities in the two forms may be compared. 
The order of the localities is arranged according to the increasing 
thickness in the Albino (taken from table 11, Sugita, 717 a, p. 
578). The average value of the cortical thickness in the mouse 
is, on the slide, 0.72 mm., and if corrected to the fresh condition 
would probably be somewhat thinner than one-half the average 
thickness of the Albino cortex. The order of the thickness ac- 
cording to localities is quite the same, so that in both forms the 
cortical thickness decreases from the frontal to the occipital 
pole and from the dorsal to the ventral aspect. Moreover, the 
cortex at the frontal pole is the thickest and has double the thick- 
ness of that at the occipital pole. 
As seen in figure 1, the cerebral hemisphere is divided by Isen- 
schmid into three main regions—the dorsolateral, frontomedial 
and suboccipital regions—separated by the double line in figure 1. 
The average cortical thickness in the dorsolateral region 
(fig. 1 a) is 0.56 mm. at its hinder-medial part and 0.90 mm. 
