10 DEAD AND LIVING MATTER 



plant under the microscope, we find that it changes in form. 

 Sometimes little swellings grow out, like knobs on a potato, 

 and these will by and by separate themselves from the 

 parent and become other yeast plants. The yeast plant is 

 alive; so is every growing plant. 



The Ameba. Figure 3 shows several specimens of 

 the ameba, an animal found in stagnant water. It is so 



small that it can be seen only 

 with a microscope. The ameba 

 consists of a single cell. It can 

 move itself about; it can change 



FIG. 3.-Amebas, magnified. ^ form; ifc ^ ^^ ^ &Q 



make other amebas. The ameba, like the yeast plant, is 

 alive. Plants and animals have life. Sand and all other 

 minerals are dead. 



Plants and Animals Grow. If we put a drop of fresh 

 yeast into a bottle containing well water with some sugar 

 and a little white of egg stirred into it, and set the bottle 

 in a warm place, in a few hours the liquid will become 

 whitish in color. This is because millions of new yeast 

 plants have formed from the few we put in. The young 

 yeast plants and amebas are at first small, but they 

 grow until they are as large as their parents. Plants and 

 animals increase in number, and grow in size. Dead 

 things can not, of themselves, grow or increase in 

 number. 



Cells. Figure 4 shows a small part of an apple leaf, 

 as it appears under the microscope. Notice that it is 

 made up of many small sacks grown together. Each of 

 these little sacks is a cell. Cells are the smallest units of 

 the building materials that make up a plant or an animal. 



