258 EXPERIMENTAL PHARMACOLOGY 



rettes contain strychnine (one cubic centimeter equals one- 

 half milligram) and adrenaline. (If a cat must be used give 

 it two grams of urethane in twenty-five cubic centimeters 

 of water by stomach, or give 1.7 cubic centimeters of paral- 

 dehyde per kilogram of animal Edmunds.) 



Insert a bladder cannula into the fundus of the dog's 

 bladder, draw off a little urine and test it with Fehling's 

 solution. Do you get a reduction ? If so how do you explain 

 it? Now consult Fig. 219 and dissect out the sciatic nerve 

 using great care not to disturb the vessels of the leg. (These 

 are carefully avoided so the curara can be well distributed 

 to the muscles innervated by the sciatic.) Stimulate the 

 sciatic with a medium strength Faradizing current and 

 note the effect on respiration and blood-pressure and on the 

 muscles of the leg below the point of stimulation. 



Beneath the skin of the back or side inject with a hypo- 

 dermic syringe twenty cubic centimeters of a saturated solu- 

 tion of curara (Merck's). This dose is exceedingly large if 

 the drug is pure, but it is usually impossible to get a first- 

 class preparation of the substance in this country. Note 

 the time of day and observe how long a time is required for 

 the drug to act (slow or Aveaken or stop the respiration). 

 How is the blood-pressure affected? (It may be necessary 

 to give more of the drug later.) Be on the watch for the 

 respiration to become shallow. How does this affect the 

 blood-pressure? Be sure to keep the anesthesia going if 

 the dose of chloretone was not sufficient to completely main- 

 tain the narcosis. This drug is supposed not to prevent 

 sensation, hence the animal must be kept anesthetized. As 

 the respiration begins to fail give artificial respiration. 

 This must be maintained during the remainder of the ex- 

 periment. 



From time to time briefly stimulate the vagus nerve with 

 a medium tetanizing current and note the effect on the 

 heart. Do you observe any change after the action of the 

 drug has become very marked? Is there any change in 



