METHODS OF INOCULATION 



689 



the piston should be removed from the barrel, as otherwise it may expand so 

 rapidly as to cause the latter to crack. 



4. When all is in readiness, the syringe being loaded and the air ex- 

 pelled, the skin is pinched up between the fingers and the needle quickly 

 inserted into the subcutaneous tissues. The injection should be given 

 slowly, and during the operation, if the patient is a child, an assistant 

 should be on hand to prevent struggling. In the illustration (Fig. 134) 

 the needle is shown connected with the barrel of the syringe by means of a 





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FIG. 134. SUBCUTANEOUS INJECTION OF SERUM. 



The site of injection is painted with tincture of iodin and covered with sterile 

 gauze fastened with straps of adhesive plaster. Just before the injection is given 

 the iodin is wiped off with a pledget of cotton and alcohol. A fold of skin is pinched 

 up between the thumb and forefinger of the left hand, the needle inserted, and the 

 serum slowly injected. The needle is then quickly withdrawn, and the puncture 

 covered with the gauze and held in place by the adhesive plaster. 



short piece of rubber tubing. This permits an injection to be given 

 without danger of the needle being broken off if the patient should 

 struggle. Most pain is experienced when the first few drops of fluid are 

 injected; after that the pain is not severe unless the tissues are suddenly 

 distended, as by a quick injection. 



The amount of serum that may be injected in one area depends upon 

 the age of the patient. Due care should be exercised against injecting 

 too much serum in one area, because of slower absorption and possible 

 necrosis of the skin and subcutaneous tissues. 

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