SEEDS AND SEEDLINGS 



79 



In other words, the food furnished new material for the plant, and 



energy for it to push its way through the sawdust or soil. We have 



proved that energy is invariably released as a result of oxidation. 



It will be of interest, then, to see 



if the grain of corn or other seeds 



can grow without a supply of 



oxygen. 



A simple method is as follows, al- 

 though this is not an accurate experi- 

 ment: Place 25 to 50 soaked beans or 

 peas in each of two wide-mouth bottles, 

 6 oz. to 12 oz. Cork and seal one; leave 

 the other uncorked, taking care to keep 

 the seeds as moist as in the covered 

 jar. Notice any differences in the seeds 

 for at least one week. Make drawings 

 showing your results.* 



Experiment to show the effect of lack 

 of air on germination. 



A more accurate method of determin- 

 ing this is to exclude air entirely from a 

 gl^-ss jar or bottle in which germinat- 

 ing seeds had previously been placed. 



Air may be exhausted by means of an air pump. If the tube is now sealed 

 by heating under the flame of a burner, the seeds will be left in an air-tight 

 jar, A jar with seeds in same condition, except for lack of air, should be 

 kept as a control experiment. 



Why did not the seeds in the covered jar germinate? We 

 have seen that to release the energy contained in a piece of coal 

 we must burn or oxidize it. To do this we must have a constant 

 supply of fresh air containing oxygen. The seed, in order to re- 

 lease the energy contained in its food supply, must have oxygen, 

 so that the oxidation of the food may take place. Hence a con- 

 stant supply of fresh air is an important factor in germination. It 

 is important that air should penetrate between the grains of 

 soil around a seed. The frequent stirring of the soil enables the 

 air to reach the seed. Air also breaks down some materials in 

 the soil and puts them in a form that the germinating seed can 

 use. What is at least one reason why the farmer plows and har- 

 rows a field ? What is at least one important use of the earth- 

 worm? 



* See Hianter and Valentine. Manual. nasrA 224. 



