328 CHESTER A. STEWART 
was compensated for by an increase in the skeleton and muscula- 
ture. The marked decrease of the ‘remainder’ in these very 
young rats may possibly be due to a decrease in body fluids, the 
percentage of which is very high in young rats (Jackson and 
Lowrey 712), (Lowrey ’13). 
In the later periods the data show considerable variability in 
the ‘remainder,’ but in most instances the weight of the ‘remain- 
der’ is higher in the later periods. 
Jackson (715 b) found considerable variability in the ‘remain- 
der’ of young rats held at maintenance beginning at three weeks or 
later, but considered it doubtful whether there is any definite 
change in the test rats, as compared with the normal. In adult 
rats subjected to acute or chronic inanition, however, Jackson 
(15 a) found a definite decrease in the weight of the ‘remainder,’ 
probably due to loss of fat. 
BRAIN 
The weight of the brain (table 2) in the test rats underfed from 
birth to three weeks of age greatly exceeds that in either the 
corresponding controls or the Wistar norm for rats of the same 
body length as the controls. There is an increase from an aver- 
age (sexes combined) of 0.616 gram for my controls to 0.985 gram 
in the test rats. This is an absolute increase of 0.369 gram, or a 
relative increase of about 60 per cent (uncorrected for slight dif- 
ferences in body weight). The average relative weight (9.80 
per cent) of the brain in this group of test rats greatly exceeds 
the normal maximum of about 6.7 per cent of the body weight 
observed by Jackson (’13) for rats weighing approximately 15 
grams. 
In the rats underfed for longer periods the weight of the brain ° 
is more nearly equal in test rats and controls. As shown in table 
2, however, even in these groups the test rats (excepting the fe- 
males at 42 days) slightly exceed the controls in absolute brain 
weight. The maximum apparent increase amounts to 13.3 per 
cent in the female at 316 days, and the average increase is about 
5.8 per cent. This is subject to a small correction on account of 
slight differences in body weight. It may also be noted that the 
