GROWTH OF THE CEREBRAL CORTEX 189 
2. The underfed rats have brain weights somewhat less than the 
standard values for the same age. 
3. The underfed rats have brain weights mar edly higher than 
the standard values for their observed body weight. 
It was already noted in the introduction that the central 
nervous system as represented by the brain suffers little or no 
loss of initial weight even in the case of severe starvation. In 
my series—-underfeeding of the albino rat at an early age—the 
body weight of the rats stunted by starvation, as compared with 
the standards for the same age, were deficient (on the average by 
litters, table 4) by from 19 to 44 per cent. On the other hand, 
the brain weights were less than the standards for the same age 
by from 4 to 12 per cent (for litters, table 4, but by from 3 to 17 
per cent for individuals, table 4 a), while for the same body weights 
they were from 15 to 29 per cent (for litters, table 4, but up to 65 
per cent for individuals, table 4 a) above the standard values. 
Considering together all the five litters (A to E) of Series I, 
in which the young were starved by separating them at an early 
age from the mother daily, it appears that the underfed rats at 
the end of the first twenty days after birth (during the suckling 
period) are about 29 per cent (average of A, T. I and II, B, T. 
handlinG 7k. la Iland hand; Ts T.and. il) behind 
the standards in body weight, while they are only 8 per cent 
(averge of the above-cited cases) behind in the brain weight. 
In Series IT and III, in both of which the young were subjected to 
early and continuous underfeeding, increasing in intensity, by 
the method of reducing the ration of milk, but without removal 
from the nest, the underfed young have shown a slightly better 
development in brain weight (in relation to body weight), the 
average being also 8 per cent (average of F, T. I and II, G, T. 
I and IJ, and H, T. I and IJ) less than the standard for the same 
age, while the body weight is on the average as much as 39 per 
cent (average of the above-cited cases) below the standard value. 
Whether removing the young from the nest increases the relative 
effect of underfeeding on the brain, as these results suggest, can 
be determined only by experiments with that question as the. 
main point in view. 
