122 



THE VITAL PROCESSES 



poses. 1 Calcium phosphate and calcium carbonate are 

 important constituents of the bones and teeth ; and the 

 salts containing iron renew the hemoglobin of the blood. 

 Others perform important functions in the vital processes. 

 The mineral compound of greatest importance perhaps is 

 sodium chloride, or common salt. 2 This is a natural con- 

 stituent of most of our foods, and is also added to food in 

 its preparation for the table. When it is withheld from 

 animals for a considerable length of time, they suffer 

 intensely and finally die. It is necessary in the blood and 

 lymph to keep their constituents in solution, and is thought 

 to play an important rdle in the chemical changes of the 

 cells. It is constantly leaving the body as a waste product 

 and must be constantly supplied in small quantities in the 

 foods. 



1 The following table shows the main elements in the body and their relation 

 to the different nutrients : 



f Carbon 

 I Hydrogen 

 I Oxygen 



Elements found 

 in the body 



In abundance 



Supplied by carbohydrates 

 and fats 



Supplied by proteids 



Supplied by different kinds 

 of mineral salts 



I Nitrogen 

 Sulphur 

 Phosphorus 

 Calcium 

 In small quanti-Jlron 



Magnesium 

 Potassium 

 Sodium 

 Chlorine 



2 The recently advanced theory that the molecules of the mineral salts, by dis- 

 solving in water, separate into smaller divisions, part of which are charged with 

 positive electricity and part with negative electricity, has suggested several possible 

 uses for sodium chloride and other mineral salts in the body. The sodium chloride 

 in the tissues is in such concentration as to be practically all separated into its 

 sodium and chlorine particles, or ions. It has recently been shown that the sodium 

 ions are necessary for the contraction of the muscles, including the muscles of the 

 heart. There is also reason for believing that the different ions may enter into 

 temporary combination with food particles, and in this way assist in the processes 

 of nutrition. 



