RESP/RA TION. 



137 



(5) Clamp tube n at the end of inspiration. Is the 

 pressure positive or negative? 



(6) You have been determining certain facts regard- 

 ing RESPIRATORY PRESSURE. Are the causes of the 

 changes of respiratory pressure the same as the 

 causes of the changes of intra-thoracic pressure ? 



(7) In what way does respiratory pressure differ from 

 intra-thoracic pressure? 



(8) Disjoin the manometer and join its tube to a re- 

 cording tambour and trace a pneumatogram, with 

 stethogram and chronogram. 



(9) Compare the pneumstogram with the tracing of 

 intra-thoracic pressure. Account for all differences. 



i Centimete 

 Scale 



FIG. 23. 



) Stimulation of the pulmonary vagus. 



(10) Count the pulse. Adjust the stethograph, re- 

 place the manometer, and during the tracing of a 

 stethogram place the mouth over the glass mouth- 

 piece; quickly blow into the tube (n) until the 

 manometer indicates two centimeters of intra 

 pulmonary pressure; clamp, count the pulse. After 

 a few seconds release the clamp and let the rabbit 

 breathe normally for a few minutes. 



Repeat the experiment. Vary by producing in turn 

 3 cm., then 4 cm. and finally 6 cm. of intra-pul- 

 monary pressure. Fix the stethogram and com- 

 pare. 



