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INOCULATION. 



XIII.— INOCULATION. 



By inoculation is meant the intentional conveyance of infectious 

 material to a healthy subject. A wider meaning is sometimes 

 attached to the term, causing it to extend to the products of micro- 

 organisms such as antitetanic and antidiphtheritic sera, mallein, etc. 

 Inoculation is a most important process in studying the life history 

 of bacteria, their nature, virulence, mode of action, etc. Animals, 

 again, are inoculated to protect them against certain diseases, like 

 black-quarter, anthrax, and swine erysipelas (rouget du pore), to pro- 

 duce new (modified) infective material (vaccine), and finally, though 

 not very often, to shorten the duration of epizootic disease. Various 

 forms of needle have been used for inoculations. The oldest is Sick's 

 (Fig. 222). A furrow in the middle of the head holds the infective 

 material. Sticker employed a special needle (Fig. 224) for pleuro- 

 pneumonia inoculations. The needle was thrust under the skin, and 

 the virus injected by pressing on the button at the side of the handle. 

 Fig. 223 represents Pessina's needle. In use the furrow is filled with 

 virus, the needle thrust into or under the skin, revolved and with- 

 drawn, leaving the infective material within the wound. 



At present, sterilisable syringes are almost universally employed 

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

 tuberculin for diagnostic purposes ; an operation which is closely 

 akin to inoculation, and is carried out in a similar way. As a rule 

 the stem of the piston carries a movable stop which can be fixed 

 at a prearranged point, allowing only the exact amount of material 



Fig. 223. 



Fig. 224. 



