GROWTH OF THE CEREBRAL CORTEX 239 
2. The underfed and the controls were killed at different ages 
(between three and forty days) and the body measurements and 
the brain weights recorded. The brain was fixed, sectioned, 
stained, and examined according to the standard procedure pre- 
viously adopted for these studies (Sugita, 717, 717 a, 718 b, ’18 ¢) 
and the size of the cerebrum, the thickness of the cerebral cortex, 
the area of the cortex in the sections, the number of nerve cells in 
a unit volume of the cortex, and the size of the pyramidal and the 
ganglion cells, were all determined and then corrected to the 
values for the fresh condition of the material, by the use of the 
correction-coefficients devised for these purposes. 
Using these data, the relative volume of the cerebral cortex 
and the number of nerve cells in the entire cerebral cortex were 
computed, employing the formulas already devised by me 
(Sugita, 718 b). All the observed and computed data were com- 
pared with the corresponding respective standard values for the 
normal Albino brain of the same weight or of the same age, as 
given in my previous papers (tables 3, 4, 5, 6, 8, 11 and 13). 
3. In Series I the underfed rats were found to be 29 per cent 
less in the body weight and 8 per cent less in the brain weight, than 
the standards for the same ages (between three and forty days). 
In Series II and III the underfed rats were 39 per cent less in the 
body weight while 8 per cent less in the brain weight. It appears ~ 
from this that starvation without removal from the nest, and the 
corresponding disturbance to the young, retards the growth of 
the brain relatively less, despite the greater arrest in the body 
growth. 
The underfed brain weight was found on the average 24 per 
cent higher than the standard for the same body weight. ‘The 
brain weights in the underfed have values between the standards 
for the same age and those for the same body weight, but generally 
fall nearer to the former. 
The brain weight is a function of the body weight: a rat which 
is more reduced in body weight by starvation has a more reduced 
brain weight. The brain weight—body weight ratio is always 
higher in the underfed than in the standard for the same age, and 
the difference between the ratios roughly indicates the severity of 
