PERCENTAGE OF WATER 129 



greater percentage of water than did the controls. The difference 

 is in the same sense in all the pairs and for both the brain and 

 spinal cord. The average figures are as follows. — ■ 



PERCENTAGE OF WATER 



average ag"e no. of cases Rrain Cord 



lTOdays 7stunted 78.618 72.613 



170daj's 7controls 78.378 71.076 



As the figures show, the percentage of water in the stunted 

 group is greater by 0.24 per cent in the brain and 1.53 per cent 

 in the cord. 



The difference in the case of the brain is about that found in 

 the preceding investigation, but that in the cord is much greater. 

 The reason for the greater percentage of water in the case of the 

 spinal cord requires still to be investigated. 



The foregoing conditions are the only ones which at the mo- 

 ment have been shown to increase the percentage of water in the 

 central nervous system of the rat, and in all cases this increase 

 seems to be associated with more vigorous growth processes. 



(b) Some conditions which decrease the percentage of water in the 

 brain and spinal cord. On the other hand, in 1904 Hatai deter- 

 mined that in rats killed at the end of three weeks of underfeeding 

 the experimented rats, though initially heavier, had on the aver- 

 age only about 44 per cent of the body weight of the controls. 



This result was due not only to an arrest of growth, but to an 

 actual loss, as measured by changes in the weight of the entire 

 body and also of the brain. At the termination of the experi- 

 ment, the brain weight in the underfed group was about 11 per 

 cent less than in the controls, approximately two thirds of this 

 deficiency being due to the arrest of growth, and one third (4.3 

 per cent) to actual loss (see table IV, Hatai '04). On the other 

 hand, the percentage of water in the brain was 



79.11 per cent in the controls 

 78.91 per cent in the experimented, 



thus showing a deficiency of 0.2 per cent in the latter. If the 

 process of the reduction of the percentage of water had been 



