48 OF PLANTS. 



We may now understand what is meant by organic 

 substances. Plants, as we have just seen, are made up 

 of organs. So are animals. The lungs are the organs 

 of breathing, the stomach is the organ of digestion. All 

 the parts of animals and plants are organized, and the 

 substances which belong or have belonged to animals or 

 plants are called organic. Mineral and all other sub 

 stances aro inorganic. 



152. Now observe what happens when the seed is put 

 into the ground. Every seed contains an embryo or 

 minute plant. This, called the sprout, you may easily 

 see in a bean, if you open it carefully. When a seed 

 is put into the earth, in a favorable state of moisture 

 and warmth, it presently begins to sprout or germinate. 

 The sprout breaks through the seed coat, and the future 

 stem shoots upward into the light and air, and the root 

 turns downward from them. 



153. As soon as the stem rises above the surface it 

 commonly spreads out two seed leaves, which had been 

 already formed in the seed. These leaves, or Cotyledons, 

 may be always seen in a bean, pea, or apple seed, which 

 has just come up. But none of the grains or grasses 

 have them. The cotyledons arc quite unlike the succeed 

 ing leaves of the plant. It is important to remember 

 this, as we often want to know both cultivated plants and 

 weeds as soon as they are up. 



154. Plants which have two seed leaves or cotyledons 

 are called Dycoteledonous (from two Greek words, dis 

 and cotyledon, meaning two-seed-leavcd.) In plants of 

 this kind there appears, between the seed leaves, as soon 

 as the plant is up, a little bud of unopened leaves called 



155. The Plumule. This soon begins to stretch upwards, 

 bearing on its summit one or two minute leaves nearly 



