300 EXPERIMENTAL PHARMACOLOGY 



the heart ? Discuss in full the action of pilocarpine, areco- 

 line (muscarine), atropine, adrenaline and barium on the 

 bronchioles. What part do the medullary centers play in 

 this action? AYhat is the innervation of the bronchioles? 

 (See Dixon and Ransom: Journal of Physiology, 1914.) 



EXPERIMENT LXXI. 

 Nicotine. (Frog: General Symptoms.) 



1. Into the anterior lymph sac of a frog inject one-half 

 cubic centimeter of one-half per cent nicotine solution. 

 Place the animal in a sink and watch its actions. Do you 

 observe anything peculiar about its attitude I When the 

 dose is too large the animal may die too quickly to show 

 typical effects. Make a sketch of the position of the limbs 

 after the action of the drug becomes marked. "\Vatch and 

 see if this stage passes off. Save the frog and observe it 

 as often as possible for several hours. Do you note any 

 convulsions at any time! On what structures does nicotine 

 act to produce these results! 



EXPERIMENT LXXIL 



Nicotine. (Frog: Heart and Vagus Nerve.) 



1. Pith the frog and take a normal heart record show- 

 ing both vagus (trunk) and crescent inhibition. Pour two 

 drops of nicotine solution (one per cent) on to the heart. 

 AVait a few seconds. Do you get an immediate effect? 

 How do you explain this ? If there is a change in the 

 heart rhythm does this continue or is there a return to 

 normal! Stimulate the vagus and note the effect on the 

 inhibition of the heart. How do you explain this ? Stimu- 

 late the crescent. Explain your results. How does nico- 

 tine cause these two results? Is the heart muscle directlv 



