m 



EXPERIMENTAL PHARMACOLOGY 



with the gas the frog will manifest distinct symptoms. 

 How long does it take to completely anesthetize the ani- 

 mal? When this stage is reached count the respirations, 

 lymph heart beats and heart beats. Inject a little oxygen 

 from time to lime and see if the animal comes out from 



Wheel wrench 



Fig. 109. Administration of nitrous oxide or oxygen to a frog. 



under the anesthetic. As the oxygen increases in the 

 bottle the frog will recover. How long does this take and 

 how long a time is required to anesthetize the frog in the 

 first place? How does this anesthetic compare with ether 

 or chloroform or ethyl bromide? 



2. Place another frog in the bottle. Note the time of 



