Securing Blood from Animals 



231 



^iaga 



When, in studying Pfeiffer'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 time, a capillary pipet can be introduced and the fluids withdrawn.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 com- 

 parison drawn by Frankel, that the injection 

 of a few minims of hqxiid 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 respiratory 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, aU that is necessary being to re- 

 strain the animal, make a minute incision in Fig. 73. — Tube for 

 the skin over the jugular vein, which is easily t^^°gi"°°^/^^°"J,t'^^ 

 found by compressing it at the root of the rabbit or guinea-pig. 

 neck and noting where the vessel expands, and 

 introducing a canula when the vein is well distended. 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 being withdrawn, the blood at once flows.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 

 shaved, or, as is easier, the hair is pulled out, leaving a clean surface 



