Body Water Compartments throughout Lifespan 109 



It appears from the series that males have a higher relative 

 content of body water than females, confirming the results 

 with the deuterium oxide method reported by Edelman and 

 co-workers (1952a) and Ljunggren, Ikkos and Luft (1957). 



This sex difference in body composition does not appear to 

 be due to a difference in the relative amounts of extracellular 

 water in the series presented. The extracellular water repre- 

 sented 22 • 7 per cent of body weight in the females and 23 • 4 

 per cent in the males. This similarity in the relative values 

 for extracellular water is in agreement with the findings of 

 Cheek (1953), of Reid and co-workers (1956) and of Ljunggren, 

 Ikkos and Luft (1957) using the corrected bromide space, of 

 Ljunggren, Ikkos and Luft (1957) using the thiosulphate 

 method, and of Griffin and co-workers (1945) using the 

 thiocyanate method. 



The lower relative content of total body water in females 

 as compared to males in the series presented is due to a 

 relatively lower content of intracellular water in the females. 

 A similar difference in the content of intracellular water 

 appears in the series studied by Ljunggren, Ikkos and Luft 

 (1957) in which the intracellular water was calculated on the 

 basis of an extracellular space measured with radiobromide as 

 well as with thiosulphate. Further evidence of the relatively 

 lower content of intracellular water in females compared to 

 males is present in the consistent findings of a lower relative 

 amount of total exchangeable potassium in females as reported 

 by Edelman and co-workers (19526), Arons, Vanderlinde and 

 Solomon (1954), Blainey and co-workers (1954), Sagild (1956), 

 and Ljunggren, Ikkos and Luft (1957). 



The lower relative body water in females indicates a higher 

 relative content of total body solids in females than in males. 

 As the relative amount of intracellular solids, as judged by 

 the relative values for intracellular water and total exchange- 

 able potassium, must be assumed to be lower in females than 

 in males, it seems justified to conclude that females must have 

 a higher relative amount of fat (or other non-cellular solids) 

 than males. 



