lings in each of the other two pots. Set all in a warm place 

 near together. Cover pots containing one of each kind of 

 corn with*large tin cans so as to exclude the light but not 

 the air. Leave for a week. Do not allow them to become 

 very dry. 



Conclusion: Is light necessary for germination? Is it 

 necessary for healthy plant growth?. 



EXERCISE No. 63 

 AMOUNT OF AIR NEEDED BY ROOTS 



Object : To learn whether roots need air. 



Material: Two bottles or glasses and some cuttings of 

 willow or Wandering Jew. 



Method: Place two or three cuttings in each bottle, 

 fill each one two-thirds full of water and over the surface of 

 one pour a thin layer of sweet or castor oil to exclude the ah-. 

 Leave them in a warm, sunny place for a week or more. 



Conclusion: Can roots grow without air? 



N. B. An excess of water in the soil largely excludes the 

 air. Could you drown a tree or a corn plant? 



99 



