Body Water Compartments throughout Lifespan 111 



and from 25-9 per cent to 22-4 per cent in females. The 

 differences mentioned are not statistically significant except 

 for the decrease in intracellular water in males (0-01> P> 

 0001). 



The tendency to a decrease in the relative values for total 

 body water found in both sexes is mostly due to a decrease in 

 intracellular water. From an unpublished study of Dr. N. W. 

 Shock (1957), in which the antipyrine space and the thio- 

 cyanate space were measured in a larger group of males, the 

 following data are of interest. A comparison of 23 subjects 



Body 



Table VI 



WATER COMPARTMENTS IN YOUNGER AND IN OLDER ADULTS. 

 RELATIVE VALUES 



Water compartments in per cent of body 

 weight with standard error of the mean 



aged 40-49 and 32 subjects aged 70-79 showed that the 

 values for total body water related to body weight decreased 

 from 54-8 per cent to 50-9 per cent, and those for the cal- 

 culated intracellular water decreased from 30-5 per cent to 

 25-1 per cent. The extracellular water changed from 24-3 

 per cent to 25-8 per cent only. The same pattern of a slight 

 decrease in total body water and in intracellular water 

 related to body weight was seen in a male series studied by 

 Olbrich and Woodford-Williams (1956). Sagild's findings of a 

 decrease in total exchangeable potassium in the old age 

 groups of both sexes can also be interpreted as evidence of a 

 decrease in the intracellular phase related to body weight 

 (Sagild, 1956). 



