RESPIRATION 109 



thoracic and abdominal movements of respiration accompanied by 

 other respiratory movements ? 



(2) With tube N (Fig. 57) open, is there any variation of the 

 mercury during respiration? 



(3) With a screw clamp slowly close tube N. As the resistance to 

 the flow of air increases, what change is noted in the manometer? 



(4) Quickly clamp tube N at end of expiration and carefully note 

 the manometer reading. Is it positive or negative? 



(5) Clamp tube N at the end of inspiration. Is the pressure posi- 

 tive or negative? 



(6) You have been determining certain facts regarding respiratory 

 pressure. Are the causes of the changes of respiratory pressure the 

 same as the causes of the changes of intrathoracic pressure? 



(7) In what way does respiratory pressure differ from intra- 

 thoracic pressure? 



(8) Disjoin the manometer and join its tube to a recording tambour 

 and trace a pneumatogram, with stethogram and chronogram. 



(9) Compare the pneumatogram with the tracing of intrathoracic 

 pressure. Account for all differences. 



(10) While dispatching the rabbit with chloroform trace a pneu- 

 matogram of chloroform narcosis. Describe its characteristics. 

 Does the heart continue to beat after the respiration has ceased? 



B. Elasticity of the Rabbit's Lungs. 



(1) After the death of the rabbit open the thorax freely, taking 

 care not to wound the visceral pleura. The lungs will collapse. Why ? 



(2) Replace the manometer; gently blow into the mouth-piece until 

 the lungs have been inflated to their normal size. Measure carefully 

 the rise of mercury in the distal column. What degree of 

 positive respiratory pressure will the elasticity of the lungs alone 

 cause ? 



(3) What is the significance of the elasticity of the lungs in respi- 

 ration ? 



C. The Cardio-pneumatogram. 



Remove the tube N from the Y-tube; join it to a recording tambour. 



(1) Let a member of a division sit in perfect repose, and, while 

 the drum of the kymograph rotates very slowly, hold the mouth- 

 piece between the lips. Hold the nose and suspend all respiratory 

 movements for a period. Let some member of the division count 

 the pulse of the experimenter. Trace the cardio-pneumatogram. 



(2) Is there a relation between the rhythm of the pulse and the 

 waves of the tracing? If so, account for this relation. 



(3) Account for the essential features of the cardio-pneumatogram. 



