FOR WAGGONER’S BIOLOGY 
55 
What is the effect of deep breathing upon the amount of fresh air 
in the lungs? What is the relation of such breathing to vigorous 
exercise? To singing? 
III. Test the complemental air for carbon dioxide by blowing it 
through clear limewater. Do the same with the reserve air. Com¬ 
pare and explain the results. Compare with results shown in 
Waggoner, Fig. 154. What do these results indicate with relation 
to the habit of deep breathing? 
EXERCISE 59 
THE ACTION OF THE RIBS AND THE 
DIAPHRAGM IN BREATHING 
I. Stand erect and take in several deep breaths. Note the 
movement of the breastbone. How far and in what direction does 
it move? Measure the chest before taking a breath. Measure 
while it is expanded. What is the difference? Note the protru¬ 
sion of the abdominal walls during breathing. What effect would 
tight clothing about the waist have upon the ability to breathe 
deeply? 
II. On the skeleton or the illustration in the text (see Waggoner, 
Fig. 140) note the position of the ribs when they are at rest. Where 
are the ribs jointed? Take in a deep breath and note the move¬ 
ment of the ribs during its inhalation. Where are the muscles 
which raise the ribs? How are the ribs attached to the breast¬ 
bone? What dimension of the chest is increased by raising the 
ribs? Why does air pass out of the lungs without effort? 
III. On the manikin, note the position of the diaphragm when 
the chest is not expanded. What happens when the diaphragm 
contracts? Why does it press down upon the abdominal organs? 
What makes the abdominal walls protrude? Give another reason 
why the breath passes out of the lungs without effort. Why, also, 
does the elasticity of the lungs help to explain this lack of effort? 
