150 NAOKI SUGITA 
4. The cell body and the nucleus of the ganglion cells attain 
nearly their full size at ten days (0.95 gram in brain weight), 
when they still show the fetal appearance. After this stage, 
the size of the cell body increases slowly but steadily as the age 
advances, while the nucleus remains nearly unchanged in size 
throughout life. 
5. Both the pyramids and the ganglion cells retain clearly 
the fetal character of form until the brain weighs 0.6 gram or 
more. The differentiation of the cytoplasm and the Nissl bodies 
begins to appear in my preparations first in a brain weighing 
something more than 0.9 gram, the latter showing first as the 
‘Kernkappe’ at the apex of the nucleus. The cells exhibit the 
mature appearance in a brain weighing more than 1.4 grams. 
6. As for the maturation of the several layers, in general, dis- 
regarding the maturation of the individual cells in them, the 
lamina ganglionaris is completed earliest, so that in a brain weigh- 
ing 1.3 grams (thirty days in age) all the ganglion cells in this 
layer are apparently mature, while at the same age the lamina 
pyramidalis is less mature as it contains relatively many imma- 
ture cells mingled with the others. The full maturity of the 
lamina pyramidalis is attained, probably, in a brain weighing 
1.6 grams (more than fifty days in age). 
7. Throughout the developmental stage of the nerve cells, the 
rate of enlargement is almost similar in the nucleus and in the cell 
body in both the pyramids and the ganglion cells; but when the 
pyramids are compared with the ganglion cells it appears that the 
rate is more rapid in the pyramids than in the ganglion cells in 
both the cell body and the nucleus during the first ten days 
after birth. 
8. The lamina granularis interna is first differentiated in brains 
Weighing more than 0.6 gram. In younger brains it is confused 
with the pyramidal layer and cannot be clearly discriminated. 
The granules attain their maximum size in brains weighing 1.0 
to 1.8 grams and then diminish slightly. The final size ( or- 
rected) of the granules in Groups XVI and above, is cell body 
15 x 20 ww and nucleus 14x 16 u. 
