298 RESPIRATION AND EXCRETION 



now in the bottle ? Test with a few tablespoonfuls of lime- 

 water. What are your observations ? 



Conclusions. 1. In what condition is the air in the room ? 



2. What is your conclusion concerning the ventilation ? 



c. Exercise and Respiration 



Method. Count the rates of breathing before and after 

 rather vigorous exercise. What are your observations ? 



Conclusions. -1. What effect on the temperature of your 

 body ? Heartbeat ? Why so ? 



2. Where does the necessary energy for vigorous exercise 

 or work come from ? 



3. Explain the effect of exercise upon the appetite ? 



d. Organic Waste 



Method. Breathe into a clean bottle, cork it, and set it 

 aside in a warm place for a day or two. Now uncork the 

 bottle and smell the air in it. What is the result ? 



Conclusions. 1. What is your conclusion ? Note. An ill- 

 smelling odor indicates the decay of organic matter. 



2. Sum up your conclusions as to the wastes given off from 

 the blood in the lungs. 



Questions 



1. Where does the energy of locomotion come from ? 



2. What are the objects of respiration ? 



3. Sum up all the products of respiration. 



4. What are the changes of air in the lungs ? 



5. What are the changes in the composition of the blood in 

 the lungs ? 



6. What is meant by oxidation ? Results of oxidation ? 



7. Trace the course of oxygen until it reaches the cells. 



8. What does a cell gain by oxidizing food ? 



