408 EXPERIMENTAL PHARMACOLOGY 



EXPERIMENT CXXVI. 

 Digitoxin. (Frog: Heart Tracing.) 



1. Pith a frog and take a normal heart tracing showing 

 both vagus and crescent inhibition. Then drop onto the 

 heart slowly a solution of digitoxin (five cubic centimeters 

 equal one milligram dissolve the drug in a little alcohol 

 and dilute to the desired strength, adding more alcohol if 

 absolutely necessary.) 



After the drug has acted for a little time stimulate the 

 vagus nerve and see if the inhibitory apparatus is paral- 

 yzed. How is the tone of the heart affected ? Is this a 



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nervous or a muscular action! Continue the application of 

 the drug and record the entire action on the heart. When 

 this heart stops compare its condition with that of the heart 

 of the frog used in the preceding experiment. AVhat con- 

 clusions can you draw? 



EXPERIMENT CXXVII. 

 Digitoxin. (Turtle: Heart Tracing.) 



1. Repeat Experiment CXXVI using the turtle's heart 

 instead of that of the frog. Is the inhibitory apparatus af- 

 fected ? 



EXPERIMENT CXXYIIL 

 Digitoxin. (Dog or Cat: Blood-pressure and Respiration.) 



1. Etherize a dog or cat and take a normal record of 

 blood-pressure and respiration. The injecting burette con- 

 tains digitoxin solution (ten cubic centimeters equal one 

 milligram dissolve the drug in alcohol and dilute with 

 water to the proper strength, adding more alcohol // abso- 

 lutely necexx<irtj). When the normal is recorded (be sure 

 the manometer pointer can pass just to the right of the re- 



