ALKALI CARBONATES. PHOSPHATES AND EARTHS. 901 



in herbivora, and in man with vegetable food rich in potash. For human 

 beings, and especially for the poorer classes of people who live chiefly 

 on potatoes and foods rich in potash, common salt is not only a condi- 

 ment, but a necessary addition to the food (BUNGE *). On the behavior 

 of chlorides, especially sodium chloride, in the animal body as well as the 

 elimination or the retention of NaCl in diseases, we have an abundance 

 of investigations, which may be found in ALBU and NEUBERG's 2 work, 

 previously cited. 



Lack of Alkali Carbonates or Bases in the Food. The chemical processes 

 in the organism are dependent upon the presence in the tissues and tissue- 

 fluids of a certain reaction, and this reaction, which is habitually alkaline 

 toward litmus and neutral toward phenolphthalein, is chiefly due to the 

 presence of alkali carbonates and carbon dioxide and in a lesser degree to 

 alkali phosphates. The alkali carbonates are also cf great importance, 

 not only as a solvent for certain protein bodies and as constituents of 

 certain secretions, such as the pancreatic and intestinal juices, but they 

 are also a means of transportation of the carbon dioxide in the blood. 

 It is therefore easy to understand that a decrease below a certain point 

 in the quantity of alkali carbonate must endanger life. Such a decrease 

 not only occurs with lack of bases in the food which brings about various 

 disturbances and death by a relatively great production of acids through 

 the burning of the proteins, but it also occurs when an animal is given 

 dilute mineral acids for a period. The importance of ammonia as a 

 means of neutralizing the acids produced or introduced into the body 

 as well as the unequal resistance of man and other animals toward this 

 action of acids has already been discussed in Chapter XIV. 



Lack of Phosphates and Earths. With the exception of the value of 

 the alkaline earths as carbonates and more especially as phosphates in 

 the physical composition of certain structures, such as the bones and 

 teeth, their physiological importance is almost unknown. The importance 

 of calcium for certain enzymotic processes and of calcium ions for the 

 functions of the muscles, and especially for cell life, gives an indication of 

 the necessity of the alkaline earths to the animal organism. Little is 

 known of the need of these earth in adults, and no average results can 

 be given. According to KOCHMANN and PETZSCH 3 we cannot conceive 

 of a certain calcium minimum (in dogs) as the Ca needs vary with dif- 

 ferent foods. With a Ca equilibrium we can cause an increased elimi- 

 nation of calcium by increasing the quantity of protein, of fat, or of 

 carbohydrate in the food and this probably depends upon a giving up 



1 Zeitschr. f . Biologie, 9. 



2 See footnote 3, page 899. 



3 Kochmann, Bioch. Zeitschr., 31, with Petzsch, ibid., 32. 



