132 NAOKI SUGITA 
taken too seriously, it may be stated that on the average the 
cell bodies and the nuclei of the pyramids attain their maximum 
size at about twenty-five days (brain weight, 1.25 grams) and 
those of the ganglion cells attain nearly the full size at about ten 
days of age (brain weight, 0.95 gram). 
The largest ganglion cells (lamina ganglionaris) in the cerebral 
cortex of the adult albino rat brain are found in the middle part 
of the sagittal section, denoted by locality III (Sugita, 717 a). 
The size of these largest cells at different ages was not syste- 
matically investigated by me, but a careful comparison of them 
with the ganglion cells at localities VII and X, tabulated in this 
study, show them to be on the average (in brains weighing more 
than 1.3 grams) 4 to 7 micra greater in the transverse diameter, 
7 to 10 micra greater in the longitudinal diameter of the cell 
body, and 3 to 5 micra greater in both diameters of the nucleus— 
all in corrected values—than the corresponding diameters of the 
ganglion cells in localities VII and X, as shown in the following 
summary : 
Average corrected diameters of the cell body and of the nucleus of the ganglion cells 
in the lamina ganglionaris (Groups XITI-XX) 
LOCALITIES VII AND X LOCALITY III 
Cells bodyaneeen cs. 28 x 37 w (average 32.4 pv) 33 x 46 uw (average 39.0 pu) 
INGICleuUstes. a5 nose | 24 x 25 uw (average 24.4 pu) 28 x 30 uw (average 29.0 p) 
The size of the cell bodies and their nuclei in the other layers 
of the Albino cortex will be considered in a later chapter in this 
paper. 
Figures 3 and 4 give the typical appearance of the pyramids 
and the ganglion cells, respectively, for each brain-weight group 
(with a few omissions), all drawn proportional in size to the un- 
corrected diameters and magnified about 950 times. 
V. MORPHOLOGICAL CHANGES IN THE CORTICAL NERVE CELLS 
DURING GROWTH 
Figures 3 and 4 illustrate the typical pyramids and the ganglion 
cells from each brain-weight group, as seen in the sections pre- 
