The Animal Body Digestion Metabolism. 



17 



Ash and nitrogen in 1000 Ibs. of farm animals (fasted live weight), milk, 



and unwashed wool. 



The table shows that the nitrogen in each 1000 Ibs. (fasted live 

 weight) of the bodies of farm animals varies from about 17 to 27 

 Ibs., being least in the fat pig and greatest in the half-fat ox. Lime, 

 the largest mineral constituent of the bones, ranges from about 6 

 Ibs. per 1000 Ibs. of carcass in the fat pig to over 21 Ibs. in the ox. 

 Phosphoric acid almost equals lime in quantity, while potash runs 

 from 1 to 2 Ibs. only per 1000 Ibs. of animal, and magnesia still less. 

 Soda, silica, iron, etc., are found in small quantities. 



26. Plants and animals compared. One of the great distinguish- 

 ing differences between plants and animals is that in plants the 

 walls of the cells of which they are composed are of carbohydrate 

 material, while in animals the walls of the body cells are of protein 

 substance. Thus plants are on a carbon and animals on a nitrogen 

 foundation. The higher plants are nourished by inorganic matter, 

 while animals live upon both organic and inorganic substances, 

 principally the former. Plants absorb thru their leaves great 

 quantities of carbonic acid gas, composed of carbon and oxygen, re- 

 taining the carbon and giving off the oxygen as waste. Animals 

 take free oxygen thru their lungs and combine it with carbon to 

 form carbonic acid gas, which is thrown off as waste in the breath. 

 Thus the two great classes of living objects are interdependent. 



In the animal body the organic material derived from plants may 

 be built into still other highly organized compounds, usually pro- 

 tein in character. Thus built, matter has reached its last high 

 stage of organized existence, but its fall or descent soon occurs. In 

 the daily waste of the body or upon the withdrawal of life, this 

 highly endowed organic matter is quickly broken down into inor- 

 ganic compounds, to begin again the eternal round of Nature. 

 3 



