BRONCHIAL TRACINGS 375 



apparatus is fully adjusted in the chest the animal is pithed 

 and the recording tambour is attached to the straight end 

 of the tracheal cannula, the side tube of the canimla having 

 a short rubber tube with an adjusting screw clamp (Hof- 

 mann's) attached to it. The ether is removed as a spinal 

 animal needs no further anesthetic at all. Pithing is car- 

 ried out by trephining the skull and destroying the brain 

 and upper part of the cord as described and illustrated in 

 Experiment LXX, page 292. (Experiment LXX should be 

 read over before this one is started as the technic is the 

 same in each and the figures given there will be needed for 

 the present experiment.) 



After the dog is pithed the head is returned to its former 

 position and the shift from positive to negative artificial 

 respiration is made. The recording tambour is attached 

 (by a glass reducer) to the short piece of three-eighths inch 

 rubber tubing on the straight end of the tracheal cannula 

 and the large boiuled tambour is adjusted to give a record 

 of about three inches in amplitude placed just above the 

 blood-pressure (which should be about three-fourths to one 

 inch above the base line). Inspiration corresponds to the 

 downstroke of the tambour. 



When all adjustments are made take three-fourths or one 

 inch of normal record (be sure everything is working all 

 right otherwise readjust the apparatus). Now with care 

 stimulate each or both vagus nerves and determine exactly 

 what influence these have on the bronchioles. What con- 

 clusions can you draw? Explain in detail. Take another 

 normal and then inject one cubic centimeter (dog) of er- 

 gamine solution. You should get an immediate response. 

 If you do not the dose may have been too small (possibly de- 

 teriorated drug but this is rare) and you can let the animal 

 recover and then give a larger dose. The right sized dose 

 will give a profound bronchoconstriction. When this is at 

 its maximum inject one-half cubic centimeter of adrenaline 

 (or four cubic centimeters of hordenine solution) and note 



