448 TOKUYASU KUDO 



terium, larger peripheral nerves, and blood-vessels, etc. The 

 escaped fluids and the loss by evaporation are not included. As 

 shown in table 2, the 'remainder' in the various tests undergoes 

 a loss in weight increasing from 37.3 per cent in the one to two 

 weeks' test to 50.9 per cent in nine to thirteen weeks. This loss 

 is probably chiefly due to that of the fat, which largely disap- 

 pears, as mentioned under ' General Observations. ' 



BRAIN 



The brain weight of the control rats (table 2) corresponds 

 closely to the data of Donaldson ('15) and Jackson ('15a). In 

 the rats at the various test periods the average brain weight shows 

 slight apparent changes, varying from —4.3 per cent to +8.6 

 per cent. It will be noted, however, that (with one exception) 

 these apparent changes are in the same direction as the corre- 

 sponding slight differences between test rats and controls in aver- 

 age body weight. The apparent differences in brain weight are 

 therefore insignificant, considering the small number of obser- 

 vations, and it seems probable that the brain undergoes no appre- 

 ciable change in weight during these thirst experiments. 



Hatai ('04) found a slight apparent loss (average about 4.7 per 

 cent) in the weight of the brain in young albino rats fed with 

 starch, beef fat, and water, the body weight being reduced about 

 30 per cent (average). In a later experiment, however, Hatai 

 ('08) found that the growth in brain weight was retarded in the 

 same proportion as the whole body weight. In albino rats with 

 retarded growth on a lipoid-free ration, the brain was apparently 

 about 2 per cent subnormal in weight (Hatai, '15). 



In underfed young rats (with water), Donaldson ('11) found 

 an apparent slight increase (3.6 per cent) in the brain weight, 

 while Jackson ('15 a) found no significant change. It is evident 

 that the age at which the inanition occurs is important, as Stew- 

 art ('18, '19) found a marked increase (125 per cent) in the brain 

 of newborn rats held at constant body weight by underfeeding 

 for sixteen days. Variot and Lassabliere ('09) observed a tend- 

 ency to persistent growth in brain weight in human infants 

 whose body weight was retarded by malnutrition. The brain 



