618 SELECTIONS FROM ADDRESSES. 



be destroyed by fire. The other is indestructible by fire. The 

 destructible portion is called the organic ; the indestructible is 

 called the inorganic, and is contained in the ash of the plant. 



The greatest relative amount of inorganic matter is about 

 the tenth day after the first appearance of the plant. From 

 the period of flowering the relative amount diminishes rapidly 

 until the plant is fully ripe, but it must be remembered, that 

 this diminution is only relative. The absolute weight continues 

 to increase through every period of its growth. 



The ivhole of the inorganic portion of the plant is derived 

 from the soil. If not naturally contained in it, the art and 

 labor of the husbandman is called in requsition to supply it. 

 A portion of the organic matter is derived from the atmosphere. 

 Some theorists maintain that the whole of it is supplied from 

 this source, while others concur with the whole body of prac- 

 tical farmers, that a portion of this supply is drawn from the 

 earth. It is very certain that corn invariably flourishes best 

 where the soil is rich in substances which contain the elements 

 of organic matter. 



Organic matter is made up of carbon, oxygen, hydrogen and 

 nitrogen. The air is composed of oxygen and nitrogen. Water 

 is a compound of oxygen and hydrogen. 



A small quantity (say one gallon in 2,500) of carbonic acid 

 gas is diffused through the atmosphere, but not chemically 

 united with it, and although there is only one gallon of this 

 gas in 2,500 gallons of air, this alone forms an ample supply 

 for all the purposes of vegetation. The source of the supply 

 of nitrogen to plants was not ascertained before Liebig's cele- 

 brated discovery of the existence of ammonia in the air, which 

 is washed down by every shower of rain, and thus brought 

 into direct contact with the organs of the plant. 



All organic substances contained in corn are formed by a 

 union of three or more of these substances. Thus sugar, 

 starch, and gum, are formed from the union of hydrogen, 

 oxygen, and carbon, in different proportions. Gluten, albu- 

 men, and caseine, contain these substances, with the addition 

 of nitrogen. 



It follows, therefore, that all these compounds may derive 

 their elements from the atmosphere, although in practise they 

 obtain a portion from the soil. 



