14 HOW CROPS GROW. 



Organic matters are in general characterized by com- 

 plexity of constitution, and are exceedingly numerous 

 and Tarious ; while inorganic bodies are of simpler com- 

 position, and comparatively few in number. 



Volatile) aist> Eixed Matter. — All plants and ani- 

 mals, taken as a whole, and all of their organs, consist of 

 a volatile and fixed part, which may be separated by 

 burning ; the former — usually by far the larger share — 

 passing into and mingling with the air as invisible gases ; 

 the latter — forming, in general, but from one to five per 

 cent, of the whole — remaining as ashes. 



Experiment 1.— A spUnter of wood heated In the flame of a lamp 

 takes fire, hums, and yields volatile matter, which consumes with flame, 

 and ashes, which are the only visible residue of- the combustion. 



Many organic bodies, products of life, but not essential 

 vital organs, as sugar, citric acid, etc., are completely 

 volatile when in a state of purity, and leave no ash. 



Use of the Terms Organic and Inorganic. — It is 

 usual among agricultural writers to confine the term or- 

 ganic to the volatile or destructible portion of vegetable 

 and animal bodies, and to designate their ash-ingredienls 

 as inorganic matter. This is not an entirely accurate 

 distinction. , What is found in the ashes of a tree or of a 

 seed, in so far as it was an essential part of the organism, 

 was as truly organic as the volatile portion, and, by sub- 

 mitting organic bodies to fire, they may be entirely con- 

 verted into inorganic matter, the volatile as well as the 

 fixed parts. 



Ultimate Elements that Constitute the Plant, — 

 Chemistry has demonstrated that the volatile and de- 

 structible part of organic bodies is chiefly made up of four 

 substances, viz. : carbon, oxygen, hydrogen, and nitrogen, 

 and contains two other elements in lesser quantity, viz. : 

 sulphur and phosphorus. In the ash we may find phos- 

 phorus, sulphur, silicon, chlorine, potassium, sodium, cal- 



