222 



EXPERIMENTAL PHARMACOLOGY 



to temperature changes caused by applying the solution? 

 How could you avoid these possible effects! Stimulate 

 the vagus nerve again and record the results. What do 

 you observe? Apply more drug (the record is made as in 

 Experiment XXXII) and try stimulating the nerve from 

 time to time. Are any changes observed? How do you 



Fig. 211.' Tracing from the heart of a turtle showing the action of strychnine. At 

 the short bar the vagus trunk was stimulated and stopped the heart for a brief period. 

 Subsequently a solution of strychnine was dropped on the heart (at X). The rate of 

 beat was apparently slightly accelerated. Later (at R.l'.S.) the vagus trunk was again 

 stimulated but could not slow or stop the heart. What structures were affected by the 

 drug? 



account for this:' How does this compare with the re- 

 sults obtained by other students? Did the turtle have any 

 convulsions? How do you explain this? 



EXPERIMENT XXXIV. 



Strychnine. (Dog: Blood-pressure, Respiration, and 

 Kidney, Spleen or Intestinal Loop.) 



1. Arrange a dog for taking blood-pressure, respiration, 

 and an oncometer tracing of either the spleen, left kidney 



