226 Experimentation upon Animals 



When, in studying Pfeitfer's phenomenon and similar conditions, 

 it is desirable occasionally to withdraw drops of fluid from the ab- 

 dominal cavity, a small opening can be burned through with a blunt 

 needle. This does not heal readily, and through it, from time to 

 time, a capillary pipet can be introduced and the fluids withdrawn. 



Small animals, such as rabbits and guinea-pigs, can be held in the 

 hand, as a rule. Guinea-pig and rabbit-holders of various forms 

 can be obtained from dealers in laboratory supplies. The best of 

 these is undoubtedly that of Latapie, shown in the accompanying 

 illustration. Dogs, cats, sheep, and goats can 

 be tied and held in troughs. A convenient 

 form of mouse-holder, invented by Kitasato, 

 is shown in the figure. 



In all these experiments one must remember 

 that the amount of material introduced into 

 the animal must be in proportion to its size, 

 and that injection experiments upon mice are 

 usually so crude and destructive as to warrant 

 the comparison drawn by Frankel, that the 

 injection of a few minims of liquid into the 

 pleural cavity of a mouse is "much the same 

 as if one would inject through a fire-hose three 

 or four quarts of some liquid into the respira- 

 tory organs of a man." 



Method of Securing Blood from Animals. 

 For many experimental purposes it becomes 

 necessary to secure blood in larger or smaller 

 quantities from animals. For horses, cattle, 

 calves, goats, sheep, large dogs, etc., this is a 

 simple matter, all that . is necessary being to 

 restrain the animal, make a minute incision in 



b 7 lood T from the the ^ OVer the W 1 " ve u in > whi * * easil y 

 carotid artery of a found by compressing it at the root of the neck 

 rabbit or guinea-pig. an d noting where the vessel expands, and in- 

 troducing a canula when the vein is well dis- 

 tended. The trocar being withdrawn, the blood at once flows. A 

 sterile tube is slipped over the canula and the blood conducted into 

 a sterile bottle or flask. 



For rabbits and guinea-pigs the technic is rather more difficult 

 because of the smaller size of the vessels. Drops and small quanti- 

 ties of blood may be secured by opening one of the ear veins, but 

 when any quantity of blood is required, the neatest operation is 

 done by tapping the common carotid artery by the method employed 

 at the Pasteur Institute at Paris. 



The animal is restrained in a Latapie holder, with the neck ex- 

 tended." Anesthesia can be used, but must be employed with great 

 care. The hair on the front of the neck is clipped and the neck 



