144 INOCULATION OF ANIMALS 



then filtered into the test-glass through a plug of sterile glass 

 wool. This is easily effected by taking a piece of |-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 porce- 

 lain 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 intravenotft 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. 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 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. The result is 

 that the hole in the side of the needle is within the abdominal 

 cavity, and the inoculation can thus be made. Intraperitoneal 

 inoculation can also be practised with an ordinary needle. The 

 mode of procedure is similar, but, after the needle is plunged 



