146 NAOKI SUGITA 
simple calculation, that at birth the largest ganglion cells are 
almost 3.1 times as voluminous, at 20 days about 2.3 times, and 
at 90 days 3.0 times, as the pyramids of the same stage, and the 
nuclei of the ganglion cells are at birth 2.8 times as voluminous, 
at 20 days 1.8 times, and at 90 days, 2.2 times as the nuclei of 
the pyramids of the same stage, if both kinds of cells are assumed 
to have the similar forms throughout their enlargement.® It is 
also seen that, using the same method, the cell body of the pyra- 
mids has increased from birth 6.1 times in volume at 20 days and 
5.4 times at 90 days, and the nuclei 6.6 times at 20 days and5.6 
times at 90 days, while the cell body of the ganglion cells has 
increased only 4.6 times at 20 days, 5.2 times at 90 days and the 
nuclei of the ganglion cells 4.3 times at 20 days and 4.5 times 
at 90 days, as compared with their initial volumes at birth. 
It may therefore be concluded that, throughout the develop- 
mental stage of the nerve cells after birth, the rate of enlarge- 
ment is almost similar in the nuclei and in the cell bodies of both 
kinds of cells, though the rate is slightly higher in the pyramids 
than in the ganglion cells in both the cell body and the nucleus 
during the first twenty days after birth, because the initial 
volume of the pyramids is small at birth. 
As the shape of the cell body is different from that of the 
nucleus, it is not proper to compare directly their respective - 
volumes as determined by the foregoing use of their diameters, 
but they must be first reduced to forms which are comparable as 
6 Here the nucleus was considered as an ellipsoid, the volume of which is to be 
calculated by the formula $7a2b, when 6 is the long radius and a is the short 
radius of the body. Asthe transverse diameter (n:) of the nucleus is equal to 
2a and the longitudinal diameter (n2.) is equal to 2b the volumes of the nuclei 
may be compared among themselves simply by the factor a*b or 2m. 
On the other hand, if the volume of the cell body was considered as a circular 
cone, in which the diameter of the basic circle is equal to the transverse di- 
ameter (c;) of the cell body and the height of the cone is equal to the longitu- 
dinal diameter (c,) of the cell body, then the volume of the cell body will be 
an (G )Pes, and the values for the relative volumes of the cell bodies may be com- 
pared on the basis of the factor ¢12c:. 
As the average diameters given in table 3 are respectively the square roots 
of the products mim, and c,¢2, the cubes of the average diameters will be approxi- 
mately proportional to the values ni2n. and c,2c., respectively. 
