ACTION OF PHYSOSTIGMIjSTE 337 



EXPERIMENT LXXXV. 

 Physostigmine. (Frog 1 : Heart Tracing 1 .) 



1. Pith a frog and obtain heart tracings showing the ac- 

 tion of physostigmine (eserine). The salicylate of eserine 

 is the best salt to use, the sulphate is deliquescent one 

 cubic centimeter equals one milligram. The solutions 

 should be freshly prepared for each experiment. 



Fig. 295. Turtle heart tracing showing the action of nicotine, arecoline and atro- 

 pine. At the places marked R.l'.S.. the right vagus nerve was stimulated. Before 

 nicotine inhibition is produced but this is absent after the drug is applied. Note the 

 temporary slowing of the heart immediately following the application of the drug. How- 

 do you explain this? The beat again becomes rapid but arecoline slows it while atropine 

 causes a return of the normal rate. Explain the actions. 



Does the drug have any action on the inhibitory appa- 

 ratus of the frog? Compare this with pilocarpine. 



EXPERIMENT LXXXYI. 



Physostigmine, Atropine, (Sodium Nitrite. (Frog: 



Stomach Ring.) 



1. Prepare a ring of the stomach of a frog and arrange 

 it in the manner shown in Fig. 292 for recording contrac- 

 tions on the drum. Is the muscle ring already in a state of 



