PARTS OF BRAIN IN NORMAL AND UNDERFED RATS’ 515 
In table 2 the data for the control groups and for the test rats 
are likewise grouped, only the averages being given. The 
original individual observations will be filed at The Wistar 
Institute of Anatomy and Biology (Philadelphia), where they 
may be consulted by those interested. 
A preliminary report of the present investigation appeared in 
the Proceedings of the American Association of Anatomists, 
Minneapolis Meeting, December, 1917 (Stewart, ’18a). 
BRAIN 
The weight of the entire brain (table 2) is considerably higher 
in the various groups of test rats than in the corresponding 
younger controls of the same body weight. In the fifteen 
individuals (9 o&, 6 @) held at birth weight for various periods 
there is an increase from an average (sexes combined) of 0.2086 
gram in the newborn controls to 0.4468 gram in the test rats, 
an increase of about 114 per cent. An inspection of the indi- 
vidual data in table 2 shows that the increase is greater in those 
rats held at maintenance for longer periods. 
As may be observed in table 2, the body length also increases, 
although the body weight is held constant. The brain weight ~ 
is also much greater in the stunted animals than in normal 
rats of the same body length, although the difference is not so 
great as when those of the same body weight are compared. 
In the test rats weighing about 10 grams at 3 weeks the rela- 
tive increase is less, amounting to approximately 33 per cent; 
while at 56 days with body weight at 12 grams the excess of brain 
weight in the test rats is about 30 per cent. In an earlier report 
(Stewart, 718 b) the brain in rats underfed from birth and weigh- 
ing 10 grams at 3 weeks of age was found to exceed that in normal 
rats of corresponding body weight by about 60 per cent, which is 
considerably more than the excess obtained for a comparable 
group in the present series. In general, however, the results 
agree in showing a stronger growth tendency of the brain in the 
younger and smaller rats. 
The increase in brain weight in spite of underfeeding with 
nearly stationary body weight is probably best shown in figure 1 
