PROBLEM 111 



129 



How does it get to the plant? Does the plant use oxygen as the 

 animal does? 



Conclusion. — 1. How are plants able to store up energy? 

 Where does it come from? What becomes of it? 



2. Explain the carbon cycle. 



3. Explain the oxygen cycle. 



,-^49 etc 



Problem 110 : To find out the course of nitrogen in its rela- 

 tion to plants and animals. 



Method. — Begin at the point of the diagram marked " Free 

 N," following the direction of the arrows. 



Observations. — What 

 do we mean by " free 

 nitrogen " ? Where is it 

 found? How do green 

 plants get the free nitro- 

 gen? In what form does 

 the nitrogen get into the 

 animal body? In what 

 form does the nitrogen 

 leave the bodies of ani- 

 mals? What causes this material and the dead bodies of animals 

 to become usable by plants? Does any nitrogen get back into 

 the atmosphere again? If so, how and when? Look this up in 

 any good book of reference. 



Conclusion. — 1. Fill out a summarizing table Hke the accom- 

 panying. 



2. In your notebook 

 explain in a well-writ- 

 ten paragraph what is 

 meant by the nitrogen 

 cycle. 



y^PIantLife Nitrous 



Bacteria/^,,^gt6t^ 



VKT- Nitrites 



^V'ates- 

 «0i0 



'Nitric Bacteria 



Problem 111: To prove a hay infusion is an unbalanced 

 aquarium. 



Materials. — Hay, glass jar, microscope, glass slides, cover 

 glasses, and pipette. 



HUNTER LAB. PROB. 9 



