NUTRITION 269 



bodies. Chlorine is in combination with sodium as sodium 

 chloride. Iron is in combination with hemoglobin. 



In the body the base forming elements are calcium, mag- 

 nesium, sodium, and potassium. The acid-forming elements 

 are phosphorus, chlorine, and sulphur. 



Acid mineral elements enter the body in organic combination 

 as follows : sulphur as a constituent of food protein including 

 horn and feathers. If sulphur is oxidized it is burned into 

 sulphuric acid and excreted in the urine as inorganic sulphates. 

 Sulphates and phosphates result from proteid tissue waste and 

 by oxidation of food protein in the body. These are elimi- 

 nated from the body as such. Phosphorus enters the body as 

 inorganic phosphates; as salts of various organic acids; as 

 lecithins (compounds of fat), phosphoric acid, and in phos- 

 phoproteins and nucleoproteins. The eliminated phosphorus 

 bj' way of the urine is in the form of di- and mono-hydrogen 

 phosphates of sodium and potassium and less abundantly 

 in the form of phosphates of calcium and magnesium. The 

 phosphorus of the feces is largely in the form of phosphates. 

 Chlorine enters the body as chlorides and is eliminated by the 

 kidneys almost wholly as chlorides. 



The organic acids of feed stuffs, such as citric, malic and 

 tartaric acids of fruits, are mostly oxidized in the animal body 

 to carbon dioxid and water, in which compounds they are 

 excreted from the body. There are formed within the body, 

 mineral acids which cannot be eliminated in this way. These 

 acids must be neutralized in order to protect the animal from ' 

 a disturbance of conditions essential to the continuance of 

 vital reactions. 



These acids are formed chiefly by the cleavage and oxida- 

 tion of proteids, either of the body or of the feed, the sulphur 

 and phosphorus contained therein, as constituent parts, 

 being oxidized to the corresponding inorganic acids. 



The practical bearing of the subject is on feeding of such 

 animals as are largely reared on cereals, namely, poultry. 



In this connection there is considered especially the acid 

 mineral elements, sulphur, phosphorus, and chlorine, and the 

 basic mineral elements, sodium, potassium, magnesium, and 

 calcium. 



