340 CHESTER A. STEWART 
instance there was a loss of about 11 per cent) the suprarenals in 
the test rats exceed those of the corresponding controls 12 to 87 
per cent. It should be noted that the weight of the suprarenals 
is slightly higher in the test females than in the males of corre- 
sponding body weight at ten weeks of age and also at all subse- 
quent periods, thus indicating the appearance of sexual differ- 
entiation during underfeeding. 
Jackson (15 b) also found the suprarenals to manifest a marked 
growth tendency in young rats held at maintenance. He noted 
a maximum increase of 39 per cent in the female underfed from 
three to ten weeks of age. Apparently the growth of the supra- 
renals was less marked than in my experiments, in which the 
underfeeding was begun earlier or carried over longer periods. As 
occurs normally, the suprarenals during underfeeding underwent 
sexual differentiation in weight, also confirming the results of 
Jackson. In adult rats, there is but little loss in the absolute 
weight of the suprarenal glands during inanition (Jackson ’15 a). 
KIDNEYS 
Using my controls as a basis for comparison, there is apparently 
an increase in the weight of the kidneys (table 2) in the rats 
underfed from birth to three, six and ten weeks of age. The 
apparent average increase (uncorrected for difference in body 
weight) amounts to about 21 per cent at three weeks, 45 per cent 
at six weeks, and 38 per cent at ten weeks. 
In the rats underfed for very long periods the weight of the 
kidney is variable, some showing an increase and others a de- 
crease. Due to this inconstancy in results, the changes are of 
questionable significance. 
In general therefore it appears that, as was observed by Jackson 
(15 b) the kidneys tend to increase in weight during the earlier 
periods of the experiment, but show no definite change during 
later periods. ‘The increase in my young rats is more striking 
than the increase observed by Jackson. This is probably due to 
the fact that my rats were placed upon the experiment at® a 
younger age, when the intensity of growth in the kidney is greater. 
In adult rats during acute and chronic inanition Jackson (’15a) 
