120 EXPERIMENTAL PHARMACOLOGY 



carefully the recovery symptoms. What principles are in- 

 volved in nitrous oxide analgesia or anesthesia ? How long- 

 does it take the animals to become normal? How does this 

 compare with ether? 



5. Eemove the alkali and allow the animals to become 

 normal, or much better, get two fresh animals (a small tur- 

 tle may also be included if the bottle is large enough) and 

 then with the animals in the bottle run in a little C0 2 . Note 

 the changes in rate and depth of respiration if any occur. 

 Add more C0 2 . Can you produce an anesthesia with CO. :' 

 Read this up in your text. Compare the symptoms in the 

 two (or three) animals. Allow the animals to recover. 



6. Paul Bert's Experiment. Replace the alkali in the 

 bottle and again run X 2 into the bottle but leave the outlet 

 open. In this way wash out the air and obtain almost a 

 pure atmosphere of N 2 0. Do not iraste any more gas than is 

 necessary. (As soon as marked symptoms of asphyxia ap- 

 pear add a little oxygen.) When nearly all of the air (nitro- 

 gen) has been run out of the bottle then close the outlet and 

 wait a little if the animals are not unconscious and do not 

 show too marked symptoms of asphyxia. Then slowly raise 

 the pressure in the bottle by admitting oxygen. Paul Bert 

 found that in an atmosphere consisting of eighty per cent 

 X 2 and twenty per cent oxygen, hut with the pressure 

 raised one-fourth above the normal atmospheric pressure, a 

 complete nonasphyxial anesthesia could be produced and 

 maintained indefinitely. Can you repeat his experiment? 

 What gas does an animal give off in its expired air? What 

 is the fate and mode of excretion of absorbed nitrous oxide? 

 In what form is it carried in the blood! How does this 

 compare with ether and chloroform or ethyl chloride or 

 ethyl bromide! What is the purpose of the alkali in these 

 experiments ! 



7. Allow the animals to recover (or obtain fresh ones). 

 Place them in the bottle (the alkali should also be in) and 



