114 



OPERATIVE TECHNIQUE. 



Nowada}'S, however, syringes are almost universally emplo\'ed for 

 protective inoculation, as well as for the injection of mallein and 

 tuberculin for diagnostic purposes, an operation which is closel}' akin 

 to inoculation, and is carried out in a similar wa}-. As a rule the stem 

 of the syringe carries a movable stop which can be fixed at a pre- 

 arranged point, allowing only the exact amount of material to be 

 injected at each operation. Such syringes are now made with asbestos 

 or metal plungers, and can be taken to pieces, or are of such a nature 

 as not to be injured by boiling. 



Before making the injection the point of operation should be 

 shaved and thoroughly disinfected. Care must be taken that the fluid 

 really penetrates beneath the skin and not into it or into the muscular 



tissue, as often happens. Ne- 

 glect of these precautions, and 

 failure to thoroughly sterilise 

 the instruments, explains most 

 of the cases of inflammation, 

 abscess formation, and other 

 complications after inoculation. 

 It almost appears as if the action of the infective material varies 

 according to whether it enters the skin or subcutaneous tissues, 

 a fact which probably explains the totally different results produced 

 by two different operators with one and the same material. The best 

 plan is to raise a fold of skin with the left thumb and forefinger and 

 rapidly thrust the needle through the skin in the length of the fold. 

 The fluid is spread over a larger surface b\- gently manipulating the 

 parts after removing the needle. 



After each injection the syringe and needle must be thoroughl}- 

 washed and boiled, or at least disinfected. 



As a rule no special restraint is needed, as the pain is very trifling. 

 In large vaccine institutes the animals are usuall}- secured on movable 

 operating tables. 



Fig. 143. — Roux's sterilisable syringe without 

 piston. 



