272 EXPERIMENTAL PHARMACOLOGY 



and watch the effect on the (corresponding) pupil. What 

 changes, if any, do you note ? How do you explain these f 



What effect has atropine in small doses on the blood- 

 pressure and respiration? A poisonous drug suddenly in- 

 jected into the circulation often gives a fall of pressure due, 

 according to some authorities, to irritation of the heart. 

 Do you believe this explanation is sufficient to account for 

 such changes? The vasomotor centers and the vessels, etc., 

 may also be specifically involved. What action has atropine 

 on the vasomotor apparatus? 



If the experiment is performed on a cat or rabbit kill the 

 animal with a large dose of the drug and secure a death 

 record. If a dog is used inject a little adrenaline and ob- 

 serve the action of this on the pupil (explain). Open the 

 abdomen and insert a cannula (Figs. 244 and 245) into the 

 pancreatic duct. Inject twenty cubic centimeters of A% 

 hydrochloric acid into the duodenum with a large hypo- 

 dermic syringe and wait ten or twenty minutes to see if 

 there is any secretion of pancreatic juice. How is the secre- 

 tion of the pancreas controlled? What action has atropine 

 on this mechanism? What effect will stimulation of the 

 vagus nerves now have on the pancreas? Try this (use 

 slowly repeated single shocks). Inject some adrenaline and 

 see if this affects the secretion. 



Kill the animal with a large dose of atropine, securing a 

 death record of the blood-pressure and respiration. What 

 is the immediate cause of death? 



2. If time permits after the animal is dead, consult Fig. 

 281 and dissect out the optic nerve at the posterior side of 

 the eye ball. Be careful not to injure the blood vessels. 

 With scissors cut the skin and fascia outwards (backwards) 

 from the outer canthus of the eye. Then seize the fascia 

 over the back of the eye ball with forceps and roll the ball 

 forward (inward). A mass of orbital fat and fascia will be 

 seen behind the eye. Carefully dissect this away and watch 

 for the optic nerve which is about three millimeters in di- 



