446 TOKUYASU KUDO 



rately without maceration, and their weights are recorded sepa- 

 rately in table 2, though also included in the weights of the whole 

 skeleton. 



As shown by table 2, while the body weight is held constant 

 during the thirst experiments, the ligamentous skeleton continues 

 to increase in weight to a marked degree. The increase is pro- 

 gressive from 14.2 per cent at one to two weeks up to 40 per cent 

 at seven to eight weeks (slightly less at nine to thirteen weeks). 

 For the cartilaginous skeleton the apparent increase in weight 

 is still greater, ranging from 22.6 to 58.4 per cent. It is possible 

 that these large percentages (especially that of 36.2 per cent at 

 one to two weeks) may be erroneous, due to abnormalities or to 

 errors in technique. 



The humerus and femur (weighed separately in the moist 

 cartilaginous state, after removal of periosteum and ligaments 

 without immersion in the hot soap solution), as shown in table 

 2, show percentage increases which are very close to those of the 

 ligamentous skeleton, and these probably form a more accurate 

 index of the actual changes in the weight of the cartilaginous 

 skeleton. 



In an underfeeding experiment, Jackson ('15 a) found that the 

 increase in young rats held at constant body weight from three to 

 ten weeks of age forms 28 per cent in the weight of the ligamentous 

 skeleton, and 21.5 per cent in the weight of the cartilaginous 

 skeleton which is somewhat lower than that obtained in the pres- 

 ent thirst experiments. This may be because less water is re- 

 quired for the growth of bone, so that its growth is less retarded 

 on a relatively dry diet. 



In the inanition experiment on young rats, Jackson ('15 a) noted 

 that the skeletal growth tends to proceed along the lines of normal 

 development, as indicated by decrease in the water content, by 

 formation and union of various epiphyses, etc. Very similar 

 phenomena were noted in the skeleton during the present thirst 

 experiments (epiphyses of vertebrae and humerus, appearance 

 of third molars, etc.). 



Data cited by Jackson from other investigators (Waters, Aron, 

 Variot) indicate that a persistent growth of the skeleton during 



