THE AIR 167 



QUESTIONS 



1. How can we show that air is necessary to keep a fire going? 



2. How can we show that a fire gives off water and carbon dioxid ? 



3. How can we show that the lungs give off water and carbon dioxid ? 



4. Why should you expect a pound of insect protoplasm to use up 

 more oxygen in an hour than a pound of earthworm protoplasm ? 



5. Why is it difficult for a person to do his usual amount of work on 

 a very high mountain ? 



6. How should you expect a decrease in the atmospheric nitrogen to 

 influence living things ? 



7. How does the gas exchange in a one-celled animal (the ameba, for 

 example) resemble the gas exchange in a one-celled plant (green slime, 

 for example) ? How does gas exchange differ in the two organisms ? 



8. How does gas exchange in a one-celled animal resemble breathing 

 in man ? How do the two differ ? 



9. How does breathing in man resemble breathing in an insect ? How 

 do they differ ? 



10. How can you show that posture is connected with a person's 

 mental state ? What use is sometimes made of this fact ? 



REFERENCE READINGS 



Hough and Sedgwick. The Human Mechanism, chap, x, Respiration. 

 Fisher and Fisk. How to Live, pp. 18-28. 

 CocKERELL, T. D. A. Zoology, chap, v, Respiration. 



