RESPIRATION AND EXCRETION 



295 



Conclusions. 1. What 

 becomes of the oxygen 

 taken in by the blood in the 

 lungs ? 



2. What is the use of the 

 oxygen? 



3. What is the purpose 

 of cell respiration ? 



4. What becomes of the 

 wastes formed ? 



5. What becomes of the 

 heat and energy formed ? 



FIG. 74. Diagram to show respiration of 

 cells. 



e. Capacity of Lungs (Optional) 



FIG. 75. Measuring the vital capacity of 

 the lungs. The bottle was filled with 

 water, which is being forced out by expir- 

 ing the air from the lungs through the 

 rubber tube slipped up into the mouth of 

 the bottle kept under water in the pan. 

 (Davison.) 



Materials. Gallon bottle, 

 cork, rubber tubing, and a 

 two-gallon vessel as a pan or 

 water container. 



Method. Fill the bottle 

 with water, invert in the two- 

 gallon pan or container, re- 

 move the cork, insert the end 

 of the rubber tubing, fill lungs 

 to their fullest capacity, and 

 force as much air as possible 

 into the bottle. 



Observations. 1. What 

 happens to the water as the air 

 enters? 



2. How much water flows 

 from the bottle? What has 

 taken its place ? 



Conclusions. 1. How 

 much air do you conclude 

 came from your lungs ? 

 1 2. If, say, 100 cu. in. re- 

 mained in the lungs, what is 

 the capacity of your lungs ? 



