1 1 2 INOCULA TION OF ANIMALS. 



bacteria already exist in a fluid there is no difficulty. The 

 needle is most conveniently filled out of a shallow conical 

 test glass which ought previously to have been covered with 

 a cover of filter paper and sterilised. If an inoculation is 

 to be made from organisms growing on the surface of a solid 

 medium, either a little ought to be scraped off and shaken 

 up in sterile distilled water or .75 per cent salt solution to 

 make an emulsion, or a little sterile fluid is poured on the 

 growth and the latter scraped off into it. This fluid is 

 then filtered into the test glass through a plug of sterile 

 glass wool. This is easily effected by taking a piece of f 

 in. glass-tubing 3 in. long, drawing one end out to a fairly 

 narrow point, plugging the tube with glass wool above the 

 point where the narrowing commences, and sterilising by 

 heat. By filtering an emulsion through such a pipette 

 flocculi which might block the needle are removed. If a 

 solid organ or an old culture is used for inoculation it ought 

 to be rubbed up in a sterile porcelain or metal crucible with 

 a little sterile distilled water, by means of a sterile glass rod, 

 and the emulsion filtered as in the last case. 



The methods of inoculation generally used are : (i) by 

 scarification of the skin ; (2) by subcutaneous injection ; (3) 

 by intraperitoneal injection ; (4) by intravenous injection ; 

 (5) by injections into special regions, such as the anterior 

 chamber of the eye, the substance of the lung, etc. Of 

 these (2) and (3) are most frequently used. When an 

 anaesthetic is to be administered, this is conveniently done 

 by placing the animal, along with a piece of cotton wool or 

 sponge soaked in chloroform, under a bell-jar or inverted 

 glass beaker of suitable size. 



1. Scarification. A few parallel scratches are made in 

 the skin of the abdomen previously cleansed, just sufficiently 

 deep to draw blood, and the infective material is rubbed in 

 with a platinum eyelet. The disadvantage of this method is 

 that the inoculation is easily contaminated. The method is 

 only occasionally used. 



2. Subcutaneous Injection. A hypodermic syringe is 

 filled with the substance to be inoculated. The part chosen 



