50 PHYSIOLOGY FOR THE LABORATORY. 



5. The two branches, or the right and the left bronchus. 



6. Sketch both the lungs and the trachea. 



c. Insert a blowpipe in the bronchus leading to the 

 uncut lung, and tie a stout cord around it so tightly that 

 no air can escape and inflate. Note the size of the lung 

 before and after inflation. Of what kind of tissue must 

 it be composed? 



d. Dissect carefully one bronchus until its branches or 

 bronchial tubes are found. Dissect one of the large 

 bronchial tubes to the surface of the lung. 



II. THE SUPPLY OF BLOOD. 



Find where the pulmonary artery and a pulmonary vein 

 enter one lung, and trace them as far as possible through 

 the lung. Make a sketch of a portion of the lung dissected 

 to show a bronchial tube, a vein, and an artery. 



B. The Changes in the Air during Respiration. 



Materials. Lime-water, about 250 c.c. Hydrochloric acid. 



Apparatus. A thermometer. A glass tumbler. A bottle con- 

 taining about 500 cc. A rubber stopper with two holes. Glass 

 tubing to fit the holes in the stopper. 



I. THE CHANGE IN TEMPERATURE. 



a. Take the temperature of the air in the room. 



b. Take the temperature of expired air by breathing on 

 the bulb of a thermometer. 



II. MOISTURE IN EXPIRED AIR. 



a. Breathe on a cold glass. 



b. What happens ? Explain. 



