BIOLOGY IN HUMAN AFFAIRS 



kilograms of carbon, nearly 4 liters of ammonia, 1.5 kilo- 

 grams of calcium, 800 grams of phosphorus, 250 grams of 

 salt, 100 grams each of fluorine, sulphur, and saltpeter, 50 

 grams of magnesium, and smaller amounts of iron, manga- 

 nese, aluminum, copper, lead, iodine, bromine, and similar 

 substances. 



The bones of the human body derive their hardness from 

 the fact that they are made largely of the salts of calcium. 

 Calcium is commonly referred to as lime. The average man 

 has about two kilograms of calcium in his body, most of 

 it within the bones and the teeth. From day to day, by the 

 processes of life, some calcium is lost from the body, and 

 it must be made up by new calcium taken in. The new 

 calcium can be had best in milk. Beside the carbon, hydro- 

 gen, oxygen, and nitrogen that are contained in milk in 

 the form of protein, carbohydrate, and fat, this fluid also 

 contains calcium, phosphorus, sodium, chlorine, and other 

 elements. 



Whereas most of the body's calcium is in the bones and 

 teeth, small amounts occur in every tissue. About one-tenth 

 of a gram of calcium is present in each liter of blood. If the 

 normal amount of circulating calcium is reduced, the human 

 being promptly has symptoms of a disturbing character. 

 Among these symptoms are the convulsive nervous phe- 

 nomena called tetany. Infants with convulsive disorders 

 are sometimes promptly relieved through the addition of 

 a proper amount of calcium to the diet. Some physicians 

 believe that many cases of hay fever and asthma can be 

 benefited by the taking of calcium. Then, too, the element 

 enters into the reactions associated with clotting of blood 

 and the prevention of hemorrhage. 



Antisepics and Dye Substances. The history of medicine 

 reveals growths and trends in epochs divided by new dis- 

 coveries which point the way to new methods of investi- 

 gation. When Pasteur announced the germ causation of 



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