THE METABOLISM OF INORGANIC SALTS. 119 



sugar. Properly conducted treatment will often cause the teeth 

 to tighten up again. 



A very common cause of death in diabetes is coma, which is 

 due to the poisoning of the animal by acid substances (oxy- 

 butyric acid) which result from the imperfect oxidation of fat 

 (see p. 116). While these acid substances are gradually accumu- 

 lating in the blood, the organism attempts to neutralize them by 

 diverting ammonia from its normal course into urea (see p. 108) ; 

 hence the ammonia content in the urine is very high in severe 

 cases of diabetes. Along with these acids and ammonia, acetone 

 also appears in the urine and breath, so that one can often diag 

 nose a severe case of diabetes by the smell of these substances 

 in the breath. Diabetes is therefore a disease which the dentist 

 should always be on the lookout for. 



Metabolism of the Inorganic Salts. Being already com- 

 pletely oxidized, inorganic salts cannot yield any energy during 

 their passage through the animal body but nevertheless they are 

 essential to life. They are used not only for the building up of 

 bones and teeth, but also for the proper carrying out of the 

 metabolic processes. In this regard they are like the lubricant 

 of a piece of machinery, the organic foodstuffs being like the fuel. 



Their indispensability is very clearly shown by the fact that 

 animals die sooner when they are fed on food from which all 

 traces of inorganic salts have been extracted than when they are 

 deprived of food altogether. This result shows us that during 

 the metabolism of organic foods substances must be produced 

 which act as poisons in the absence of inorganic salts. Some of 

 these poisonous substances are no doubt acid in reaction because 

 life can be prolonged for some time by merely adding sodium 

 carbonate to the salt-free food. But salts not having any 

 neutralizing powers are also necessary to keep the animal 

 alive. 



The chief salts which we take with our food are the chlorides, 

 carbonates and organic acid salts (e. g., citrates, tartarates, etc.) 

 of sodium and potassium and of calcium. We also take some iron 

 and traces of iodine. All of these are already present in suffi- 

 cient amount in the ordinary foodstuffs, except sodium chloride, 



