156 NAOKI SUGITA 
TABLE 9 
Comparison of diameters of cortical cells in the Norway and the albino rats. The 
data used here are the averages in Groups XIII to XX and in Groups N XIII 
to N XX, taken from tables 3 and 8. Differences in diameter and in volume are 
calculated here, the data of the Albino being taken as the standard of comparison 
2 PYRAMIDS GANGLION CELLS 
AVERAGE 
BRAIN WEIGHT 
Cell body Nucleus Cell body Nucleus 
grams 7 7 i 7) Lu 
IA bInOse ee oe oak 1.691 22.9 18.8 32.4 24.9 
INOE Ways oo --2e 1.694 23.7 19.6 34.9 26.3 
Difference in diameter...... 3.5% 4.2% GIG 5.6% 
Difference in volume....... 10.9% 1B11G% 24.9% 17.8% 
This summary shows that in mature brains of like weight, the 
pyramids (cell body and nucleus) in the Norway exceed those 
in the Albino in avérage diameters by about 4 per cent and in 
volume by about 12 per cent, and the ganglion cells (cell body 
and nucleus) in the Norway exceed those in the Albino in aver- 
age diameters by about 7 per cent and in volume by about 20 
per cent, if the Albino be taken as the standard of comparison. 
It may be said, therefore, that in the Norway the ganglion cells 
in the lamina ganglionaris exceed much in size those in the Albino, 
while the pyramids in the Norway-are only somewhat greater 
than those in the Albino. 
In chart 4, which gives a comparison of the nerve-cell sizes 
between brains of presumably the same age in the two forms, it is 
shown clearly that the changes in sizes of cell body and the 
nucleus according to age are quite similar in both forms. The 
pyramids attain the maximum size at about twenty to thirty 
days (in the Albino in brains weighing 1.1 to 1.8 grams, in the 
Norway in brains weighing 1.3 to 1.5 grams, which both come to 
the same relative position in the curves), and after that they de- 
crease slowly. The ganglion cells in the Norway grow more 
rapidly than those in: the Albino, even in later life. In the 
latter the ganglion cells remain almost unchanged in size in 
brains weighing 1.0 to 1.6 grams, while those in the Norway 
increase in size rather steadily as the age advances. 
