MINERAL METABOLISM 311 



deprived of Mg, Na or Cl or of all three. If deprived of K growth is not 

 very satisfactory and when deprived of both Na and K it ceases Lack 

 of Ca or P is promptly followed by a slowing of growth. 



Water 



Of all the body constituents water is present in greatest proportion 

 and except in the bones and fat it comprises more than one half the weight 

 of the fresh substance. Three factors exert their influence on the water 

 content of the body and of the individual organs. First, the age. The 

 fetus has the highest percentage of water, at the third' month 94 per 

 cent, which falls rapidly so that by the fifth month it is approximately the 

 same as at birth, 66-69 per cent (Camerer and Soldner). In the adult it 

 is 58-63 per cent. Second, the nutritional condition of the organism. 

 With poor nutrition the water content of the body increases, as a result of 

 loss of fat, since water and fat are present in the tissues in quanti- 

 ties which vary inversely (Voit(fe)). The ingestion of carbohydrates 

 (Weigert(a)) and of NaCI favors water retention. Strauss(rf) claims 

 that for every 10 to 15 grams of salt retained iy 2 -2 kg. of water are 

 retained, and he considers this a "sero" rather than a tissue retention. 

 Third, a pathological condition is in many cases, especially in fibrile dis- 

 eases, accompanied by water retention. Balcar et al. consider this to be the 

 result of a poisoning of the tissues which causes them to combine with 

 excessive quantities of water, thus interfering with regulation of body 

 temperature by surface evaporation. By the injection of a solution con- 

 taining 5 per cent NaCl and 1 per cent Na 2 CO 3 until diuresis deprived the 

 body of large quantities of water they were able to produce fever experi- 

 mentally, and they compare this fever with the salt or inanition fever of 

 new-born infants, both of which disappear on the administration of water. 



Sakai's analyses of the blood of new-born infants as compared with 

 that of nursing infants and adults show a lower percentage of water, and a 

 higher percentage of salt in the new-born, H 2 O : Xa.Cl == 122, than in 

 either of the others, H 2 O : NaCl == 140 142. The maximum water con- 

 tent of the blood occurs at about three months of age and a too long con- 

 tinued liquid diet for babies is apt to prolong the period of high blood 

 dilution with pathological consequences (Lederer; Widmer(6)). The 

 normal water content of the blood is occasionally decreased in diabetes but 

 pathological conditions usually result in its increase. 



Edema is a water retention accompanied by salt retention which 

 Fischer (6) considers the result of an accumulation of acid in the body 

 (acidosis) since he has shown experimentally that increased II ion concen- 

 tration promotes the absorption of water and of NaCl by protein. Hender- 

 son does not consider this explanation adequate because he finds no in- 



