186 



EXPERIMENTAL PHARMACOLOGY 



graph drum. These movements do, however, with many 

 drugs, record very profound and striking changes in the 

 bronchioles. (Can you detect any evidence of this when 

 morphine is injected into the femoral vein?) But the im- 

 portant point in the oxygen record is the gradual rise of 

 the lever as the oxygen in the pan is consumed by the dog. 

 The rate of this rise determines the rate of oxygen con- 

 sumption. Watch carefully and when the lever reaches a 

 satisfactory altitude (this will vary with each experiment 

 and the student with a little practice can estimate about 

 when to stop), which will generally be about two inches 

 if a large drum is used (lower and less magnified if a 

 small drum is used), then suddenly stop the drum and at 



Rubber bath cap 



9 



das inlet 



9*W Cake pan 

 Flanqeonpan 

 Added flanqe 



Gas outlet 1 



Fig. 177. A simple gas reservoir made from a very shallow, wide, round cake pan 

 with two spouts soldered into the walls. A large bath cap is stretched over the pan 

 and serves to form an adjustable gas reservoir suitable for use with the apparatus 

 shown in Fig. 176. A small spirometer ( 1 or 2 gallons) may also be used as a reservoir. 

 The spirometer should be delicately counterpoised as the oxygen is not delivered from 

 the wash bottle under a high pressure. A large, thin walled rubber bag may also be 

 used. 



once run a fresh supply of oxygen into the pan. The lever 

 comes down and when the base line is reached stop the 

 oxygen inflow and immediately start the drum. (If the 

 drum is exceedingly slow the oxygen can be run in while 

 the drum is turning. This is very convenient.) When the 

 lever again reaches its former high point stop the drum 

 and at once reinject oxygen. This gives a saw-tooth like 

 record. And the distance between each two consecutive 

 teeth or descending narrow lines in the record gives a 

 measure of the relative amount of oxygen consumed dur- 

 ing that period of time. Tf a drug which slows the con- 



