72 PRACTICAL PHYSIOLOGY 



middle of the right side of the chest in the axillary line while the 

 person breathes, and describe the sounds heard at each place, timing 

 their relationship to inspiration and expiration. 



(Read Text Book on the Mechanism of the Breath Sounds.) 



4. The Rate of Respiration 



Count the number of respirations in a person who has been and is 

 sitting still and whose attention is directed to something other 

 than his breathing, and again in the same person after taking violent 

 exercise. 



5. Collapse of the Lungs when the Thorax is Opened 



Distend the rabbit's lungs provided by blowing into the trachea 

 and then observe their elastic collapse. Measure the force of this 

 with a water manometer. 



Examine a section of lung stained with orceine to show the elastic 

 tissue, and note its abundance. 



6. Recording the Movements of Respiration 



(a) To record the movements of the air. Arrange a slowly moving 

 drum by putting the drum on the slow gear and connecting a small 

 spindle on the shafting to the largest on the drum. Connect a 

 recording tambour by means of a piece of rubber tubing with a 

 short piece of glass tube. Push the movable base-piece of the stand 

 against the stop, and by moving the whole stand bring the point 

 of the lever lightly against the drum. Insert the glass tube into one 

 nostril, breathe with the mouth closed, and record the movements 

 of the lever. The upstroke and downstroke should occupy about 

 1 inch on the drum. Adjust the speed of the drum to secure this. 

 When a trace has been taken for about a minute, swing the lever off 

 the drum by means of the movable base-piece, put a time record in 

 seconds on the drum and measure the duration of inspiration and of 

 expiration. 



The record should be taken with the subject sitting still, and not 

 looking at the drum. 



(The precautions as regards disinfecting the nasal tube, p. 12, 

 note, must be observed.) 



(6) To record the movements of the chest wall. Insert in the course 

 of the rubber tube a glass T tube with a clamp. Connect the glass 

 tube with a toy balloon, and place it under the waistcoat or a 

 bandage round the chest, and slightly distend the balloon. Take a 

 tracing. 



The Influence of Carbon Dioxide on Respiration 



Put the drum on a very slow speed so that in ordinary breathing 

 the upstroke and downstroke are just separate from one another on 

 the tracing. 



(1) While taking a trace of normal breathing by means of a tube 

 in the nostril, hold the breath till a marked desire to breathe again 



