494 Our Surroundings 



in the air unites with the food stored in the seed, producing 

 energy to promote growth. The embryo, or baby plant within the 

 seed, will not develop unless supplied with moisture, oxygen, and 

 heat as well as food. 



Experiment to Show Oxidation in Living Things. We have 

 learned that oxidation produces heat and carbon dioxide. Here 

 is an experiment to show that plants as well as animals give off 

 heat and carbon dioxide as a result of the oxidation that goes on 

 in their bodies. 



Read a thermometer and then put it into a jar of sprouting 

 seeds. Put the cover on the jar. Wrap the jar in some material 

 to prevent the escape of heat and leave it for two or three days 

 in a place of uniform temperature. At the end of this time notice 

 any change in the temperature in the jar. Place a small amount 

 of lime water in a small container in the jar. Does the lime water 

 turn milky ? Does this experiment indicate that germinating seeds 

 give off heat and carbon dioxide? Hold a thermometer in your 

 hand and notice any change in the temperature recorded. Breathe 

 into lime water. Do you conclude that oxidation goes on in living 

 things ? 



Absorption and Food-storing. A green plant has a function 

 which an animal does not have, that of making and storing food 

 within itself. From the soil the roots of the plant absorb food 

 materials in solution, which pass through the plant until they 

 reach the leaves, where carbon dioxide is absorbed from the air 

 and combined with them to make food. This food is stored in 

 the roots, stems, seeds, and leaves. A part of this stored food is 

 later digested and used by the plant for carrying on its life 

 processes. The part stored in the seed is used to nourish the 

 embryo, or baby plant in the seed, until it can grow food for itself. 

 Healthy plants, however, make and store more food than they can 

 use. They are the food-makers of the world. 



Osmosis. You will remember that food in a liquid state is 

 absorbed into the blood through the membranes of the stomach 

 and intestines, and that oxygen is absorbed from the air into the 

 blood through the membranes of the lungs and carbon dioxide is 

 given off from the blood to the air. Plants, too, absorb and give 



