184 



ELEMENTS OF AGRICULTURE 



nitrogen, sulphur, and a litttle phosphorus. But 

 though they are made up of the same elements, they 

 are different compounds, and differ in appearance and 

 in the proportions in which the elements are combined. 

 The nitrogen compounds are by far the most important 

 compounds of the animal body. 



175. Non-Nitrogenous Substances. — The non-nitrog- 

 enous matter of plants is made up principally of starch, 

 sugar, gum, and woody matter, usually with small 

 quantities of oil or fat. In animal bodies, on the other 

 hand, nearly all of this matter is fat or oil. No starch 

 or woody matter is found in animal bodies, and only a 

 little sugar. 



The amount of fat in animal bodies varies greatly. 

 Different animals contain very different amounts of fat, 

 and the same body varies from day to day in the 

 amount of fat it contains. The non-nitrogenous mat- 

 ter of animal bodies is made up of the same elements 

 as the non-nitrogenous matter of plants; namely, car- 

 bon, hydrogen,, and oxygen. These elements are, how- 

 ever, combined in a different way, and the fats of 

 animal bodies are different in appearance from the 

 fats of plants. Thus lard is quite a different thing 

 from cottonseed oil, though they both contain the same 

 elements. 



176. Mineral Matter, or Ash. — Most of the mineral 

 matter of animal bodies is contained in the bones, and 

 only small quantities are found in the flesh and blood. 

 Older animals as a rule contain more ash than younger 

 animals. This is because their bones are larger and 

 better developed. As a large part of the bones of all 



