428 TOKUYASU KUDO 



resulting changes in organ weights are in general very similar, 

 although the experiments lasted but a few days. The extensive 

 investigations of McCarrison ('19), however, have shown that 

 in animals (pigeon, guinea-pig, monkey) on vitamine-deficient 

 diets the various organs present atrophic changes, which resemble 

 and are in some way related to those occurring in ordinary 

 inanition. 



The evident fact that the changes in organ weights in the 

 present thirst experiments are in general very similar to those 

 found during total inanition and in partial inanition of various 

 kinds, may perhaps be explained in one of two ways. Either 

 the effects of thirst closely resemble those of general inanition 

 (perhaps in some way interfering with the normal process of 

 metabolism) or they are masked and overshadowed to a large 

 extent by the inanition which necessarily accompanies the thirst 

 experiments, due to the inadequate food-intake. Further 

 research will be necessary before this problem can be solved. 



SUMMARY 



The more important results of the present investigation may be 

 suiruiiarized briefly as follows: 



In the acute-thirst experiments, lasting from six to sixteen days, 

 the amount of water in the diet was greatly reduced in eight test 

 rats, resulting in a loss of 36.1 per cent in the average gross body 

 weight in a few days. The corresponding percentage changes in 

 the organs are most readily seen in table 3. 



In the chronic-thirst experiments, lasting from forty-seven to 

 fifty-five days, the amount of water in the diet was not so greatly 

 reduced, resulting in a more gradual but greater loss of body 

 weight, the loss in average weight of seven test rats being 52.4 

 per cent in about seven weeks. The corresponding percentage 

 changes in the various parts are most readily seen in table 3. 



In a single rat, after total inanition, the loss in body weight 

 was 47.2 per cent in eleven days. The apparent loss in the 

 individual parts is very similar to that during thirst (especially 

 the chronic) series (table 3) , making due allowance for the differ- 



