520 Cc. A. STEWART 
In the stunted rats kept at birth weight for various periods, 
and also in those weighing approximately 10 and 12 grams at 
three and eight weeks, respectively, the weight of the cerebrum 
(table 2) considerably exceeds that of the normal younger con- 
trols of corresponding body weight. For the first group (sexes 
combined) there is an increase from an average of 0.1358 gram 
in the controls to 0.3144 gram in the test rats, an increase of more 
than 131 per cent. In the test rats at three weeks (22 days) 
the increase in the cerebrum is relatively less, amounting to 
approximately 29 per cent, and at eight weeks it has decreased 
to about 19 per cent. 
As to relative proportions, the percentage weight of the cere- 
brum is slightly higher in the test rats kept at birth weight var- 
ious periods than in the controls, the apparent increase being 
from an average of approximately 64 per cent of the combined 
weight of the separate parts in the latter to 67 per cent in the 
stunted individuals. The range in the test rats is from about 
63 per cent to 69 per cent, increasing in general with the length 
of the experiment. If we now compare the corresponding change 
in relative proportion of the cerebrum during normal growth, it 
is evident that with the increase in brain weight from birth 
there is normally an increase in the percentage that the cerebrum 
forms of the entire brain, similar and practically equal to that 
noted in the brain of equal size in the stunted rats. 
In the test rats weighing about 10 grams at three weeks, how- 
ever, there is apparently a slight decrease (71 to 69 per cent) in 
the relative size of the cerebrum as compared with the controls 
of the same body. weight. Likewise during normal growth there 
is a similar decrease in the percentage weight of the cerebrum 
while the brain weight is increasing from about 0.6500 gram to 
0.8700 gram. At eight weeks of age the cerebrum in the test 
rats, though absolutely larger, is relatively smaller than in the 
control. This change likewise is probably associated with the 
usual tendency toward declining relative size of the cerebrum in 
normal brains of corresponding weight, although the difference 
in this case is greater than would be expected from the apparent 
change during normal growth. 
