WILLIAM TOWNSEND PORTER 9/ 



When a dog is brought to the laboratory for opera- 

 tion he is given a hypodermic injection of morphine. 

 After the morphine has taken effect, the dog is fastened 

 upon the operating table. By this time he does not feel 

 the discomfort of being tied down. He is then fully an- 

 esthetized with ether. Rabbits are fastened upon rabbit- 

 boards and anesthetized with a mixture of three parts of 

 ether and one of alcohol. As a rule, we do not employ 

 chloral, for observation shows that the American rabbit is 

 killed by a dose which the European rabbit bears safely. 

 Cats cannot, of course, be handled like the rabbits. The 

 cats are placed in a small box. A small box is chosen 

 in order that when the ether is poured into it and the ani- 

 mal attempts to escape from the fumes of the anesthetic, 

 his- movements shall be so limited that he cannot suffer by 

 them. After full anesthesia is reached, the cat is taken 

 out and fastened to the holder, while the anesthetic is 

 continued. 



In researches upon the physiological action of drugs it 

 is not always possible to keep the animal anesthetized 

 throughout the experiment, for the reason that the effect of 

 the anesthetic on the heart-beat, the secretions, and other 

 functions might conceal the effect of the drug which is be- 

 ing studied. In such cases the animal is anesthetized during 

 any necessary operation, for example, the insertion of a 

 cannula into the carotid artery in order to record the 

 blood-pressure, and then the anesthetic is partially or 

 wholly withdrawn, while the effect of the drug is tested. 

 The inexperienced, seeing the open wound, would sup- 

 pose that the animal must suffer keenly; but this is not 

 the case. A wound made with a sharp instrument is not 

 necessarily painful, even in man. The pain of wounds 

 comes from pressure upon the sensory nerves, -- as, for 

 example, when the bruised part swells and the liquid 

 which causes the swelling presses upon the nerves, or 



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