338 CHESTER A. STEWART 
and ten weeks), however, the spleen shows a marked tendency to 
growth, the average apparent increase being about 27 per cent. 
In rats underfed for longer periods, beginning at three weeks of 
age, on the contrary, there is an apparent decrease in the weight 
of the spleen, except in the four females at 412 days. On account 
of the extreme normal variability of the spleen, however, the 
apparent atrophy during the later fasting periods may be of doubt- 
ful significance. It is nevertheless in agreement with the doc- 
trine that lymphoid tissues in general tend to atrophy during 
inanition (cf. Jolly et Levin, 711). 
Jackson (715 b) noted a reduction in the weight of the spleen in 
young rats during the earlier periods of underfeeding (beginning 
at three weeks), while at later periods there was no material 
change in weight. In adult rats during chronic inanition the 
average loss in weight is nearly proportional to that of the entire 
body while in acute inanition the loss appears very much greater 
(Jackson 715 a). 
STOMACH AND INTESTINES 
The average weight of the stomach and intestines (including 
contents) is 1.10 grams (table 2) for my controls at one week. 
This is somewhat higher than the normal weight 0.735 gram 
obtained by Jackson (’13) for a large series of the same age. The 
difference is not entirely due to a difference in the amount of the 
contents, for the weight of the empty alimentary canal (0.36 
gram) likewise averages higher than Jackson’s weight (0.296 
gram), 
The weight of the contents of the alimentary canal (obtained 
by deducting the weight of the empty from the full alimentary 
canal) is much lower at three weeks in the test rats than in the 
controls. At six and ten weeks of age, however, the weight of the 
contents is excessively heavy in the underfed rats. In the later 
periods of underfeeding the data are variable but show a tend- 
ency to decrease. . 
Jackson (’15 b) noted an increase in the contents of the alimen- 
tary canal during the early periods of underfeeding, while during 
the longer experiments the change (a tendency to decrease) was 
