ACTIOX OF VERATPJXE 439 



When all adjustments are made take a normal and in- 

 ject one cubic centimeter of veratrine solution. Do you get 

 an intestinal record! The dose was probably too small but 

 the toxicity of commercial preparations varies greatly and 

 some samples are exceedingly poisonous. When once you 

 have determined the dose which your animal can withstand 

 then inject a larger amount and watch for intestinal con- 

 tractions. (One group of students should also record the 

 bladder contractions.) The respiration should be affected 

 rather early. Watch for the heart to become slower. This 

 will be seen in the increased amplitude of the manometer 

 tracings. 



The action of the drug should now be brought on slowly 

 as with aconitine and digitoxin. This is the best way to 

 bring out the central vagal stimulation which slows the 

 heart. The beating of the heart should finally become very 

 slow and the amplitude of each beat as recorded by the 

 manometer may reach half an inch or more in length. If 

 you succeed in getting this action then suddenly cut both 

 vagus nerves and see if the heart accelerates as after aconi- 

 tine. Does veratrine make the heart more irritable? Do 

 you get a stage of irregular heart beats as occurs with 

 aconitine ? Kill the animal by repeated injections of the 

 drug. What general conclusions can you draw from the 

 experiment ! If another group of students are performing 

 the experiment at the same time then one group can give 

 the animal an injection of one cubic centimeter of atropine 

 (one cubic centimeter equals one milligram) instead of cut- 

 ting the vagus nerves. A third group may let the veratrine 

 take its regular course of action, neither cutting the vagi 

 nor giving atropine. The groups can compare their results. 



Examine your respiratory record closely and see whether 

 any indications of a Cheyne-Stokes type of breathing are 

 present. Is the respiratory disturbance due to a central or 

 a peripheral action ? 



