SEED GERMINATION 71 



forming a thin, white coating on the sides and bottom of 

 the bottle. 



Conclusions. — Would the limewater turn milky if no 

 carbon dioxide came in contact with it? Where must the 

 carbon dioxide in the fruit jar come from? Could any 

 carbon dioxide come off from the seeds in the jar in Exer- 

 cise 20, which contained the boiled water covered with oil ? 

 Why not? Thinking back over Exercises 10 and 11 and 

 Sections 17 and 49, state (1) what it is that the seed takes 

 from the air ; (2) what becomes of this substance that the 

 seed takes from the air ; (3) what the seed gives up to the 

 air; (4) and four ways of shutting air away from the 

 planted seed. When wood is burning, the carbon which 

 it contains is uniting with oxygen. Why can we not start 

 the fire if the dampers are tightly shut in the stove? 



50. Heat generated during Germination. — Whenever 

 carbon and oxygen unite, forming carbon dioxide, heat 

 is generated. In this manner, heat is produced in our 

 bodies when the material containing carbon in the blood 

 unites with the oxygen from the lungs, forining carbon 

 dioxide. So heat is generated when fuel containing carbon 

 in the stove unites with oxygen, forming carbon dioxide. 

 This being true, should we not expect heat to be produced 

 when the stored food, which contains carbon, in the ger- 

 minating seed unites with oxygen, forming carbon dioxide ? 

 Let us prove that this is the case. 



EXERCISE 23 



Object. — To show that germinating seeds give off 

 heat. 



Procedure. — Boil a large handful of wheat, beans, or 

 other seeds for several minutes to kill the embryos. When 

 the seeds are cool, place them in a medium-sized bottle. 



