GROWTH OF THE CEREBRAL CORTEX 209 
TABLE 10—Continued 
Connie. ||| NUMBEE OF CELLS IN 0.001 mm.# 
SERIES, LITTER AND TEST AVERAGE serra TION 
GROUP CONTROL AGE far coBFFiI- | Lamina | Lamina | Ganglion 
VsGRRRCEE Mt CIENT pyrami- | ganglio- cells in 
dalis naris jlam.gangl 
days grams 
Series [II 
G a-g [eAuT, 11+ 0.844 1.24 149 94 24 
h-j 40S ML 22— 1.154 1.26 108 80 20 
Average APs 11— 0.753 1.21 185 |, 114 3 
(Ser. I-III) AP, JO 20— 1.107 1.29 113 79 20 
Average C.I 8— ORL00R | tots 215 134 42 
(Ser. I) Coit 19+ 1.226 1.24 110 77 22 
sum of the cell numbers in the lamina pyramidalis and the lamina 
ganglionaris, which may be regarded as representing the average 
cell density in the cerebral cortex, are also given in table 11, as 
N, and compared with the corresponding standard values for the 
brains of the same age, taken from a former paper (Sugita, 18 b). 
When compared in this way, it is seen that the observed cell 
number in a unit volume is generally higher than the standard in 
brains which weigh less than 1.0 gram (T. I groups). The excess 
in cell number in underfed brains weighing less than 1.0 gram 
(T. I groups) is on the average 17 per cent, and that of the con- 
trol brains weighing less than 1.0 gram (C. I groups) is on the 
average about 7 per cent. On the other hand, the average cell 
number of the underfed brains weighing more than 1.0 gram 
(T. II groups) is almost equal to, while that of the control brains 
weighing more than 1.0 gram (C. II groups) is less by 4 per cent 
than, the standard for the same age. The underfed brains are 
underdeveloped in weight and the brains weighing less than 1.0 
gram (T. I groups) contain those of ages up to sixteen days. 
These relations lead me to conclude that, in the underfed brains 
weighing less than 1.0 gram or under sixteen days in age, the cell 
density denoted by N (the average cell number in two unit 
volumes) is distinctly high, when compared with the normal 
brains of the same age, probably because the brain size or weight 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 29, NO. 3 
