THE INFLUENCE OF CHEMISTRY. 101 



///. — Mineral Constituents of the Food. 



(Lime, Potassa, Soda, Magnesia, Iron, Sulphur, Phosphorus, 

 Chlorine, etc.) 



The relations of the mnieral constituents of the animal body 

 lo the life of animals were not better understood before 1840 

 than those found in plants to the life of plants. Liebig's 

 well-known extensive investigations concerning the functions 

 of certain mineral substances in the growth of plants, induced 

 him to study their relations to animal life. He compared the 

 mineral constituents of the food consumed with those found 

 in the animal body ; he studied the distribution of the various 

 mineral elements throughout the dilTerent organs of the body 

 ^and within the secretions and the excretions of the animals 

 on trial. In the course of these investigations he noticed the 

 alkaline reaction of the blood, found the soda the principal 

 alkali in the blood and in the bile, and the potassa in the 

 flesh, and recognized the hydrochloric acid as a constituent 

 of the liquid of the stomach. 



These and similar important results caused him to assert, 

 for the first time in the history of animal physiology, that a 

 definite supply of certain mineral substances is indispensable 

 for the continuation of life. His special views may be 

 gleaned from the following personal statement. 



"The inorganic or saline substances which form the con- 

 stant constituents of the blood, of the flesh, of the muscles 

 and of every other organ, exert an important and, in many 

 instances, even a conti'olling influence on the process of 

 animal respiration, digestion, assimilation, secretion and ex- 

 cretion. They im})art to the organic portion of the food, the 

 power of supporting animal life ; without them no food is 

 complete.'" 



Actual experience has fully confirmed his statements. To 

 feed merely the mineral constituents of the fodder articles is 

 equal to starvation, and to deprive the normal animal food of 

 its essential mineral constituents before feeding it carries 

 with it the destruction of life wherever such material is ex- 

 clusively fed. Judging from experience in plant growth, it 

 seems but reasonable to assume that in compounding fodder 

 .rations for our various kinds of farm animals the mineral 



