THE PLANT 39 



of these forces. Take a lily, snowball, or other white flower, and 

 put the stem in a vase of water colored with red ink. The reddened 

 water is drawn up through the stem, and colors the flower. 



Plant Food from Air. We know that a plant absorbs food 

 through its roots. This is important and necessary. If you, cut 

 off the root, the part of the plant above ground will die for lack 

 of nourishment. But by far the greater part of its food about 

 ninety-five per cent is derived from the air. Wonderful it is, 

 yet true, that from the invisible air, to a large extent, the plant builds 

 up its substantial body. The elements derived from the air are 

 carbon, oxygen, hydrogen, and nitrogen. Carbon dioxide, which 

 is carbon and oxygen, is taken in by the leaves. Oxygen and 

 hydrogen, in the form of water, pass down into the soil and 

 are taken in by the roots. The nitrogen, in compounds pre- 

 pared chiefly by bacteria in the soil, also enters through the 

 roots. 



A Leaf. Let us examine a leaf under a microscope. It is 

 composed of cells which are as colorless as glass. Stored in these 

 cells is a green coloring matter called chlo'ro phyl, or leaf green, 

 which is formed from iron salts in the sap. Wherever there 

 is greenness in the plant, there is chlorophyl, in stems and 

 branches, but especially in leaves. Chlorophyl can be formed only 

 in sunlight. That is the reason a plant which grows in a dark 

 place is pale and colorless. How much prettier is the green plant ! 

 But the green coloring matter is not for beauty alone, though 

 we may well believe this is one of the purposes of our Heavenly 

 Father, its Creator. 



On the leaf, chiefly on the under side, are many little openings 

 or mouths. Through these it takes in the carbon dioxide of the 

 air. By the action of chlorophyl and of sunlight, this gas is sepa- 

 rated into oxygen and carbon. Most of the oxygen is returned to 



