102 ANIMAL BIOLOGY 



a. State the location of the lungs with reference to 



the head and the cavity of the trunk. 



b. Describe the appearance of the lungs. 



c. Insert the end of a glass tube, that has been 



drawn out to a small diameter, into the glottis 

 opening and blow air into the lungs. Describe 

 what you have done and state the result. 

 5. Name in order the openings, the cavity, and the tube 

 through which the air must pags in order to 

 reach the lungs. 



C. Breathing movements. 



1. Place a frog in a glass jar with an inch or two of water 



and watch the action of the floor of the mouth. 

 This is one of the breathing movements. De- 

 scribe this breathing movement of the frog. 



2. There are two breathing movements of the sides of 



the trunk, one a very active inward and out- 

 ward movement, and the other a very slight 

 inward and outward movement. When you 

 have seen these two kinds of movements of 

 the sides, describe them and state which kind 

 occurs the more frequently. 



D. How the frog exhales. 



1. What effect will the active inward movement of the 



sides have upon 



a. The size of the body cavity ? 



b. The size of the lungs ? 



c. The pressure of the air in the lungs ? 



2. When the sides of the trunk move actively inward, 



will the air move into the lungs or out ? Why ? 



3. Through what passages will the air go from the lungs 



to the outside of the frog ? 



E. How the frog inhales. * 



1. When the floor of the mouth moves downward 

 a. Will the size of the mouth cavity be made larger 

 or smaller ? 



