142 INOCULATION OF ANIMALS 



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 bouillon or '85 , 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-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 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: (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 substance of the lung, etc. Of these (2) and (3) 

 are most frequently used. When an anaesthetic is to be ad- 

 ministered, 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 with 1 to 1000 corrosive 

 sublimate, or by dropping upon 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 then sealed with a 

 little collodion. 



3. Intraperitoneal Injection. This may be performed by 

 means of a special form of needle. The needle is curved, and 

 has its opening not at the point, but in the side in the middle 

 of the arch (Fig. 47). The hair over the lower part of the 

 abdomen is cut, and the skin purified with an antiseptic. The 

 whole thickness of the abdominal walls is then pinched up 



