GROWTH AFTER INANITION FOR VARIOUS PERIODS. 45 



norm plus 36.0 and 16.1 per cent., respectively. The relative 

 weights of the glands (.054 per cent, for the female and .035 per 

 cent, for the male) shows that sexual differentiation in weight had 

 appeared. An increase with sexual differentiation in the weight 

 of the suprarenal glands in young rats held at maintenance was 

 likewise observed by Jackson ('15). 



Following refeeding, the weight of the suprarenals was con- 

 stantly below the Wistar norm to a variable extent for the first 

 four weeks. In the controls at sixteen weeks of age, the supra- 

 renals were slightly (4.2 per cent.) above the norm. This would 

 indicate that the excess weight accumulated by the suprarenal 

 glands while the body weight remained constant did not persist; 

 but on the contrary the glands appear to lag behind their normal 

 proportions in the growth of the body upon refeeding. It is of 

 course barely possible that this deficiency in the weight of the 

 suprarenals in the refed rats may be due to chance variations. 



In the adult rats, the suprarenals were also below Donaldson's 

 norm, but as compared with the controls the glands were slightly 

 heavder in the test animals. The differences however are small, 

 and probably not significant. 



It may therefore be concluded that the suprarenals, in which 

 growth is persistent during maintenance, lag behind upon 

 refeeding and appear even to drop below the norm. In those 

 refed to the adult stage, however, there is no marked difference 

 between test animals and controls. 



20. Kidneys (Table V.}. 



The kidneys appear to be slightly below normal weight for 

 corresponding body length at the end of nine weeks of under- 

 feeding. The differences, however, are small and probably not 

 significant. Jackson ('15) observed that in rats held at constant 

 body weight there was a slight tendency to increase in the weight 

 of the kidneys, in the earlier weeks, but little or no apparent 

 difference later. 



During the first four weeks of refeeding, in the majority of cases 

 the kidneys were slightly heavier than Donaldson's norm. At 

 sixteen weeks, the kidneys were 23.5 per cent, above the norm 

 in the female refed rats, and 15.4 per cent, in the controls. 



