1 14 LABOR A TOR Y G UIDE IN PHYSIOLOG Y. 



tion through the agency of a clamp and support; some- 

 times, however, better results may be secured by holding 

 the stethograph in the hands, supporting the wrists on 

 the edge of the rabbit board. 



b. Intra=thoracic pressure. 



Locate an intercostal space to the right of the ster- 

 num and opposite its middle point. Make an incision 

 0. 5 cm. long, parallel with the intercostal space and 1 cm. 

 from the sternum. Dissect through the intercostal mus- 

 cles, taking care not to cut the pleura. Insert the point 

 of the glass cannula into the wound, press it carefully 

 through the pleura into the right pleural cavity. 



Join the rubber tube to a recording tambour and un- 

 clamp. Slowly and gently manipulate the cannula until 

 there is evident communication through the lumen of the 

 cannula and tube from the pleural cavity to the tambour. 



So adjust the cannula that the recording lever makes 

 the maximum excursion. Bring the levers into such a 

 relation to the kymograph that the tracing point of the 

 stethograph lever shall be vertically over that of the 

 lever which is to record intra-thoracic pressure, and about 

 two centimeters from it. 



c. Intra=abdominal pressure. 



Make, in the median line of the abdomen, a one-cen- 

 timenter incision, limited anteriorly by the xiphoid ap- 

 pendix. After partially dissecting through the abdom- 

 inal wall insert the cannula into the incision and care- 

 fully press it through the peritoneum. If one push 

 the cannula between the diaphragm and liver he will 

 usually be successful in getting the free end of the can- 

 nula into an open space. Care should be taken not to 

 wound the liver. Take tracing as in b. 

 <. Observations. 



a. External respiratory movements. 



