Body Water Compartments throughout Lifespan 105 



Within the body water compartments the measurements 

 with thiosulphate demonstrated a relative decrease of extra- 

 cellular water during growth. A similar degree of decrement 

 in extracellular space with advancing age has been reported 

 by Ely and Sutow (1952) using the thiocyanate method, and 

 by Cheek (1954) using the corrected bromide space. The 

 relative values for intracellular water in the series presented 

 stayed about the same throughout infancy and childhood. 

 No similar investigations are available in the literature, but it 

 is interesting that Corsa and co-workers (1956) found that 

 the total exchangeable potassium as related to body weight 

 stayed the same throughout infancy and childhood. As about 

 95-98 per cent of the exchangeable potassium must be present 

 within the cells their results can be taken as corroborative 

 evidence for Friis-Hansen's (1956) findings of the relative 

 constancy of the intracellular water. 



An alteration in the interrelationship between the extra- 

 cellular and intracellular water during growth thus appears. 

 When the extracellular water is expressed as a percentage of 

 total body water the extracellular compartment decreases 

 from 55 per cent in the youngest group to 38 per cent and 28 

 per cent in the two oldest groups, again reflecting the relative 

 decrease of the extracellular water. This altered relationship 

 between the extra- and intracellular water is another impor- 

 tant facet in the body compositional changes during growth. 



The alterations during growth could be produced in two 

 ways : (1) They could be due to a proportional alteration in the 

 composition of all tissues, or (2) they could be caused by an 

 intracellular increase in some tissues whereas other areas would 

 develop in a different way. 



Histochemical studies are helpful in the interpretation of 

 this problem. Kerpel-Fronius (1937) found in studies of 

 muscular tissue from human newborn babies and from adults 

 a relative increase in intracellular phase during growth, 

 whereas such a change did not appear in the skin or in the 

 central nervous tissue. Kerpel-Fronius also drew attention 

 to the fact that the total muscle water had increased from 



