GROWTH AFTER INANITION FOR VARIOUS PERIODS. 3! 



4. Extremities and Trunk (Table IV.}. 



The relative weight of the upper extremities 8.5 and 9.1 per 

 cent. (Table IV.) in the two rats killed at the end of nine weeks of 

 maintenance, compares closely with the relative weight (9.3 per 

 cent.) obtained by Jackson and Lowrey ('12) for the normal three 

 w r eek rat. According to Jackson ('15), there is apparently a 

 slight decrease in the relative weight of the fore-limbs in the test 

 rats from 9.3 per cent, to an average of 8.8 per cent., which, 

 however, might be due to accidental variation. 



On refeeding, the relative weight of the forelimbs gradually 

 decreased, reaching an average of 7.4 per cent, (sexes combined) 

 at the end of the second week, with average net body weight of 

 72.8 grams. Jackson and Lowrey ('12) found the upper extrem- 

 ities to form on the average 6.7 per cent, of the body in rats 

 weighing 79.2 grams net. The weight then in my rats refed 

 two weeks, although slightly higher, is therefore nearly normal.' 

 At the end of four weeks of refeeding the upper extremities were 

 also slightly heavier in the test rats than in the controls; but in 

 the adult rats the relative weight was practically normal in the 

 refed individuals, as compared with the controls. 



In general, therefore, the forelimbs appear practically normal 

 throughout the various refeeding periods, though perhaps rela- 

 tively somewhat heavy at the end of two and four weeks of 

 refeeding. 



The lower extremities (Table IV.) formed 15.8 and 17.7 per 

 cent, of the body in the two rats killed after maintenance for 

 nine weeks. This is practically identical with the normal at 

 three weeks of age (15.7 per cent.) found by Jackson ('15), who 

 also found no distinct change in the weights of the extremities in 

 young rats held at maintenance for considerable periods. 



On refeeding, the relative weight of the lower extremities at 

 the end of the second week averaged 17.1 per cent, of the average 

 net body weight (72.8 grams) w r hich is slightly higher than the 

 value (14.9 per cent.) observed by Jackson and Lowrey for rats 

 averaging 79.2 grams. At the end of four weeks of refeeding the 

 lower extremities were relatively lighter in the test rats than in 

 the controls, whereas in the adult the weights were practically 

 identical in the refed and control animals. 



