312 HENRY A. MATTILL AND HELEN I. MATTILL 



creased colloidal swelling in II ion concentrations within the ranges that 

 occur in the body or the urine, and because acidosis is not always accom- 

 panied by edema. 



The requirement of the body for water is of course dependent to a 

 degree on climatic and occupational variations, but under comparable con- 

 ditions a child requires more water per kg. of body weight than an adult. 

 Bart let t is of the opinion that a child 6 months old needs 122 g. water 

 per kg. and an adult 35 g. Widiner(fe) considers that a child 6 months old 

 should receive 115 g. per kg. ; a child 1 to 2 years old 65-110 g. water per 

 kg. and that 85 g. is the optimum ingestion for a 2-year-old child. The 

 daily loss of water through the lungs is 400-500 g. for adults. Lack of 

 water, if accompanied by the ingestion of food, results in increased pro- 

 tein metabolism (Spiegler). A fasting animal is supplied w r ith water for 

 its body needs by the catabolism of its own tissues, and usually shows little 

 inclination to drink. Excessive water drinking, in fasting or with food, 

 causes temporarily increased N elimination followed by improved protein 

 economy (Fowler and Hawk, Orr). 



Sodium Chlorid 



In how far sodium chlorid is a food and in how far it is a condiment, 

 is a question which is open to discussion and which is not of particular im- 

 portance. A certain amount of it must be considered a necessary food 

 constituent for all but strictly carnivorous animals who suck the blood, 

 as well as eat the flesh and bones of their prey, but there is no doubt that 

 habit has resulted in the use of much more NaCl in the human dietary 

 than is physiologically necessary. Albu-Neuberg state that 1-2 g. of NaCl 

 daily. is sufficient. While custom varies considerably the average daily 

 intake is probably nearer 8-10 gr. Bunge's explanation that the need of 

 NaCl by herbivora and animals living on a mixed diet is due to the pre- 

 ponderance of K over Na in grains, vegetables and flesh and that the ab- 

 sorption by the blood of the salts from these foods leads to a loss of blood 

 Na and Cl which must be compensated by ingestion of Nad, is still gener- 

 ally accepted. According to this theory the K and Na salts from the food 

 enter the blood as organic salts or as phosphates and since the ratio of 

 K to Na is higher than in the blood, the excess of K salt reacts with NaCl 

 in blood, producing KCL and a Na salt, both of which are excreted by the 

 kidneys thereby impoverishing the body of NaCl. Koppe has added to 

 this the theory that salt hunger may be due to a lack of ionized salts in vege- 

 table foods, 



The relation of salt to water retention has already been mentioned 

 (p, 311). This matter has been attacked experimentally from different di- 

 rections with interesting results. Cohnheim and his co-workers have shown 



