128 INOCULATION OF ANIMALS. 



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. 



j. 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 

 for inoculation is either near the root of the tail, or between 

 the scapulae, the advantage being that the animal cannot 

 suck the point of inoculation in such situations. The hair 

 is cut off the part, and the skin purified with i to 1000 cor- 

 rosive sublimate. The skin is then pinched up and, the 



