CHAPTER XXIII 

 The Non-Nitrogenous Organic Compounds of Plants 



223. Organic flatter. The organic matter of a plant 

 or material of any kind is that portion which can be 

 converted into volatile or gaseous products ; it is 

 the combustible part, and is simply a mechanical mix- 

 ture of the various organic compounds, as starch, sugar, 

 and fat, of which the material is composed. The term 

 organic compounds was originally applied to those bodies 

 which it was believed could be produced only as the re- 

 sult of life processes, but it is no longer used in that sense 

 because many of the organic compounds are now produced 

 in the laboratory by synthetic methods independent of 

 life processes. The organic matter of a substance is ob- 

 tained by subtracting the ash from the dry matter. The 

 dry matter of wheat, for example, contains 2.10 per cent, 

 ash and 97.90 per cent, organic matter. The organic 

 matter of plant and animal bodies includes a number of 

 classes and types of compounds. 



224. Non-Nitrogenous and Nitrogenous Organic Com- 

 pounds. For purposes of study, the organic compounds 

 of animal and plant bodies are divided into two large 

 classes : (i) nitrogenous, and (2) non-nitrogenous. This 

 division is made on the presence or absence of the element 

 nitrogen. The nitrogenous or nitrogen-containing com- 

 pounds are those in which the element nitrogen is in 

 combination with carbon, hydrogen, oxygen, and small 

 amounts of other elements, while the non-nitrogenous 



