338 GENERAL SCIENCE 



can use only soluble foods, and since starch is but very 

 slightly soluble, it is changed to sugar which is easily 

 soluble for the use of the plant. 



The conditions necessary for these enzymes to act 

 are also the conditions necessary for rapid germination. 

 What is the temperature of the air in the room where 

 plants are growing? What is the temperature of the air 

 outside when seeds are planted? By experimenting we 

 shall find that a temperature near 75 F., or 24 C., is 

 favorable for the germination of seeds. A moderate 

 amount of moisture, or enough to keep the seeds damp, 

 is best. The seeds of the most useful plants will not 

 germinate if they are covered with water or if the soil 

 is kept too wet. The reason for this is that germinating 

 seeds need air, and they cannot get sufficient air while 

 covered with water. Place some beans and corn in water 

 for several days and see if they will grow. The conditions 

 necessary for germination are a moderate temperature, 

 a moderate amount of moisture, and air or oxygen, as 

 they use only the oxygen of the air. We can easily prove 

 that light is not necessary for germination by giving 

 some seeds the three necessary conditions and then 

 wrapping them in black paper to exclude the light. 



234. Roots. We recall that we saw in beans and corn 

 the part of the young plant which during germination 

 becomes the first true root of the plant, and that we 

 observed that the root grows first during germination. 

 The root grows into the soil to get water and soluble food 

 for the stem and top of the plant. Roots take water 

 and food from the soil before all the food in the seed or 

 grain is consumed. The way in which roots take up soil 

 water is an interesting process and to learn how it is done 

 we shall have to perform some simple experiments. 



