344 CHESTER A. STEWART 
In the test rats underfed for very long periods, however, the 
hypophysis is variable. In the test males at 412 days there is 
an apparent average decrease in absolute weight from 0.0033 
gram to 0.0028 gram, a loss of over 15 per cent. The decrease in 
the males at 291 days of age amounts to approximately 21 per cent. 
On the other hand, in the females fasting for long periods there is 
no such decrease. In fact for the one female at 316 days the 
weight of the hypophysis shows no change, whereas at 392 and 
314 days there is an apparent average increase of approximately 
10 and 11 per cent respectively (subject to slight correction for 
difference in body weight). It should be noted that the weight of 
the hypophysis is slightly higher in the very old test females than 
in the males, suggesting that sexual differentiation in weight has 
occurred. 
In general, therefore, it appears that the hypophysis increases 
considerably in weight in underfed rats during the earlier periods. 
In the very long experiments however the sexes appear to react 
differently. The weight of the hypophysis in the males appar- 
ently suffers a loss during very prolonged fasting, but in the 
females it shows a slight increase in weight. Jackson (15 b) 
similarly noted a distinct tendency to an increase with the appear- 
ance of sexual differentiation in the weight of the hypophysis in 
rats held at constant weight from three to ten weeks of age. Dur- 
ing inanition in adult rats the relative weight of the hypophysis 
is practically unchanged (Jackson 715 a). 
Quite recently Jackson (’17) has studied the valine’ changes in 
the lobes of the hypophysis in rats underfed for various periods. 
In young rats kept at constant body weight the pars anterior is 
somewhat reduced in relative size, the intermedia and nervosa 
becoming correspondingly larger. 
PINEAL BODY 
The weight of the pineal body (table 2) is practically normal in 
each group of test rats when compared with the corresponding 
controls. The slight differences which exist (especially in some of 
the older groups) are of doubtful significance, especially when the 
exceedingly small size of the gland is taken into consideration. 
