138 INOCULATION OF ANIMALS 



filtered into the test-glass through a plug of sterile glass wool. 

 This is easily effected by taking a piece of f -inch glass-tubing 

 3 inches 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 quartz 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 : (1) by scari- 

 fication 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 cardiac chambers, 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 occasion- 

 ally used. 



2. Subcutaneous Injection. — A hypodermic syringe is charged 

 with the fluid to be inoculated. The hair is cut off the part to 

 be inoculated, and the skin purified by rubbing into it some 

 strong solution of iodine. The skin is then pinched up, and, the 

 needle being inserted, the requisite dose is administered. The 

 wound is sealed with a little collodion. 



3. Intraperitoneal Injection. — The hair over the lower part 

 of the abdomen is cut, and the skin purified with iodine. The 

 whole thickness of the abdominal walls is then pinched up 

 between the forefingers and thumbs of the two hands, and the 

 needle is plunged through the fold thus formed. If the wall is 

 then relaxed, the point of the needle will be within the abdominal 

 cavity, and the inoculation can thus be made. 



4. Intravenous Injection. — The vein most usually chosen is 

 one of the auricular veins. The part has the hair removed, the 

 skin is purified, and the vein made prominent by pressing on it 

 between the point of inoculation and the heart. The needle is 

 then passed obliquely into the vein, and the fluid injected. That 



