326 CHESTER A. STEWART 
MUSCULATURE 
The absolute weight of the musculature (table 1) averages 
constantly higher (except in the four test males at 412 days, 
and in one female at 316 days) in the underfed rats than in the 
controls of corresponding body weight. The apparent increase 
in the individuals underfed from birth to ten weeks from 3.85 
grams to 4.24 grams (sexes combined), however, represents an 
increase of only 10 per cent. The greatest excess is in the four 
test males at 291 days, in which the weight of the musculature 
exceeds that of the (younger) controls by about 20 per cent. 
At other ages, however, the differences are not Very striking. 
In the exceptional cases mentioned above the average weight 
of musculature for the test rats is slightly below that for the 
(younger) controls of the same body weight. 
In general, therefore, it appears that the musculature in the 
test rats differs only slightly from that of the controls. The 
averages, however, indicate a slight increase in weight in the 
majority of cases. On account of the difficulty in removing the 
musculature completely in a uniform manner, the exceptions 
may be due to experimental error, rather than to variability in 
the musculature. 
Jackson (15 b) likewise observed but slight change in the 
weight of the musculature in young rats kept at constant body 
weight, although in the majority of cases there was a slight 
tendency to increase. Since the tendency is even greater and 
more constant in my series, it may be concluded with a fair de- 
gree of certainty that in young rats of various ages held at main- 
tenance for various periods the musculature shows a slight but 
definite tendency to increase in weight in the great majority of 
cases. 
During both acute and chronic inanition in adult rats, Jackson 
(15 a) found the musculature to lose relatively in nearly the 
same proportion as the whole body, the loss being somewhat 
greater in chronic than in acute inanition. 
