1 16 LAB OR A TOR Y G UIDE IN PHYSIO L OGY. 



(13) Is the intra-thoracic pressure affected by the ex- 

 periment ? If so, explain the effect. 



(14) If two phenomena correspond perfectly in their 

 cycles, and if a variation of one is always accom- 

 panied by a variation in the other, can there be any 

 reasonable doubt that they sustain to each other the 

 relation of cause and effect ? 



(15) Is one of the phenomena in question the cause 

 of the other? If so, state which is the cause and 

 establish your position. 



To measure intra thoracic pressure. 



(16) Clamp the rubber tube of the pressure appa- 

 ratus. Replace the recording tambour \\ ith a water 

 manometer. Unclamp. 



Is the pressure during inspiration positive or negative, 

 and how much ? 



(17) Is the pressure during expiration positive or 

 negative, and how much ? 



(18) If the whole apparatus were filled with water 

 instead of air and water, would it make any essen- 

 tial difference in the result? What effect do the 

 variations of the intra-thoracic pressure have upon 

 the circulation ? Upon the respiration ? 



c. Intra-abdominal pressure. 



Trace upon the drum a stethogram and chronogram as 

 well as a record of the intra abdominal pressure. 



(19) Does the rhythm of varying intra abdominal 

 pressure correspond with the rhythm of the respira- 

 tory movements ? 



(20) With what phases, respectively, of the respira- 

 tion do rise and fall of the intra-abdominal pressure 

 correspond ? 



('21) What influence upon the circulation would rise 

 of the intra-abdominal pressure exert? 



