486 PHYSIOLOGY. 



pensable to life. Without mineral salts in the food the proteids in 

 decomposition give up sulphur, which is oxidized in great part and 

 becomes sulphuric acid. The cells are injured by it and its presence 

 in the blood is not compatible with life. There is caused a train of 

 symptoms indicating a disturbance of the central nervous apparatus 

 and the digestive system. 



Sodium Salts. Chlorine is not united with proteid, but exists 

 always in an inorganic form. Sodium chloride in moderate doses 

 reduces nitrogenous metabolism. When sodium chloride is withdrawn 

 from the diet of man his weight decreases, for water is lost with sodium 

 chloride. In starvation small doses of sodium chloride increase the 

 water in the tissues and render the animal more capable of resistance. 

 When the body is deprived of salt the blood becomes somewhat con- 

 centrated. Osmotic pressure explains in part the close relation between 

 the quantity of water and that of sodium chloride. 



The uniformity of osmotic pressure is in part due to the con- 

 stant proportion of sodium chloride present, which exerts 50 per cent, 

 of the osmotic pressure. 



In human serum Hamburger has calculated 25 per cent, as non- 

 electrolytes, that is, organic substances; whilst 75 per cent, consists 

 of electrolytes that is sodium chloride, 50 per cent, and 25 per cent, 

 of other salts, as sodium carbonate, etc. 



Salt is necessary to the constitution of the blood, lymph, the 

 formation of bile and gastric juice. It also keeps in solution many 

 nitrogenous compounds which are eliminated by the urine. The 

 vegetarian should eat more salt, as the salts of potash in the vege- 

 tables exceed by three times the salts of soda. 



Now, the bases in the blood which neutralize are the sodium 

 carbonate and sodium phosphate; and it has been estimated that the 

 amount of this alkaline reacting alkali, or native alkali, in the entire 

 body is equivalent to 60 grams of sodium hydroxide (NaOH). This 

 amount of alkali is so small that it would be quickly exhausted by a 

 persistent acid intoxication, with a persistent formation of only small 

 amounts of acid. Certain diabetic patients pass daily, for long 

 periods, a large amount of acids which are excreted by the urine in 

 combination with bases, it being understood that the urine does not 

 contain free acid. As the native alkali of the body is not sufficient to 

 neutralize so much acid, it is necessary that there should be another 

 and more enduring source of alkali than the native. For this 

 ammonia is generated by proteid metabolism of the cells, and 

 especially of meat. The acids in diabetes are aceto-acetic and the 



