CHAPTER II 

 PLANTS AND THEIR FOOD 



6. Environment is a general term for all the condi- 

 tions that surround an animal or plant, such as air, 

 soil, water, light, temperature, other plants or animals, 

 etc. 



7. Culture seeks to make the environment favorable 

 to the particular plant or animal, or to produce plants 

 and animals better adapted to the environment. The 

 most important conditions are those that affect the 

 supply of the substances used for food by the plant or 

 animal. To encourage the growth of, say, a corn plant, 

 we destroy the weeds that would injure it, and cultivate 

 the ground to make a better home for its roots. To 

 intelligently cultivate plants, we must first learn how 

 plants grow and get their food. 



8. Not All Plants Use the Same Kinds of Food. Not all 

 plants are like those familiar to us, as trees, herbs, etc . 

 Possibly we do not often think of the yeast put in the 

 dough to make the bread " rise," or the " green scum " 

 on the ponds, as plants, yet they are, though very simple 

 ones. The yeast which we get from the grocery store 

 as " compressed yeast " is only a mass of millions of 

 very small plants, each one composed of a tiny mass of 

 living substance, called protoplasm.* This mass of 

 protoplasm is surrounded by a delicate membrane, 

 called a cell-wall. These plants are so small that they 



^Protoplasm (meaning primitive substance) is the older term for that part 

 of the cell having the property of life. Some writers prefer the term bioplasm, 

 (meaning living substance). 



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