GROWTH OF THE CEREBRAL CORTEX 147 
explained in the accompanying note and then table 5 may be con- 
sulted again.’? It is seen from table 5 that at birth the entire 
cell has almost double the volume of the nucleus, so that the 
cytoplasm and the nucleus have nearly the same volume. The 
nucleus-plasm relation changes according to the brain weight. 
In the pyramids, the total cell body comes to 1.7 times at 20 
days and to 1.8 times at 90 days, compared with the volume 
of the nucleus at the same age. This is owing to the relatively 
rapid growth of the nucleus. In the ganglion cells, on the 
other hand, the total cell body is 2.2 times at 20 days and 2.4 
times at 90 days, compared with the volume of the nucleus at 
the same stage. As the pyramids decreases in size after 30 
days, the cell size of the pyramids in old age (brain weight more 
than 2.0 grams) becomes almost equal to that at 8 days of age, 
but the nucleus-plasm relation is quite different at the two stages. 
At 8 days the nucleus is relatively large (total cell body is 1.7 
or less times the nuclear volume), but in old age the volume of 
cytoplasm has increased somewhat in relation to the nuclear 
volume (total cell body is nearly 2.0 times the nuclear volume). 
These values for comparison were taken from the data here 
used alone, but, as already noted, sections which were taken 
from material fixed in 95 per cent alcohol or in Bouin’s fluid and 
imbedded in celloidin show a nucleus which is relatively smaller. 
In series of sections which have been prepared by methods other 
than that used by me, the volume relations between the cell body 
and the nucleus (nucleus-plasm relation) would probably be dif- 
ferent from those which I have reported here, but I think it will 
be fair to assume that the growth changes in the cell body on 
7 Tf the cell body were considered as having an ellipsoidal form with diame- 
ters equal to ¢; and c, which denote respectively the transverse longitudinal diam- * 
: a 3 
eters measured on the cell body the volume, would be i(3)*(G) or agTer'C2. 
And if, on the other hand, the same cell body were considered as a circular cone, 
C 1 , 
the volume may be calculated by in(Z) 2¢5, OF omeves. As the difference between 
these two formulas is not higher than of cc, I have here compared the 
aus 
96 
volumes of the cell body and of the nucleus under the assumption that both have 
the ellipsoidal form, employing once more the figures given in table 5 as the 
basis of comparison. 
