74 PRACTICAL BACTERIOLOGY 



and the glass flask, and the material to be filtered poured into the 

 filter. It is necessary to attach a piece of rubber tubing with a pinch- 

 cock at D, because the tube C is attached directly to the tube of a 

 suction-pump, and filtration produced. It works well with a water 

 force of 1 J atmospheres, and a mercury vacuum meter of 200 mm. 



CXXXVII. INOCULATION OF ANIMALS. 



Inoculation is practised on animals to determine if an organism is 

 pathogenic or disease-producing ; and if so, the pathological results of 

 its growth in the tissues of these animals, and the manner in which 

 the organism gains entrance to the tissues in order to produce these 

 results. The animals usually employed in laboratories for inoculation 

 purposes are white mice, grey house mice, field mice, rats, guinea-pigs, 

 rabbits, and pigeons. The inoculations are made subcutaneously, 

 intravenously into the great serous cavities, or into the anterior 

 chamber of the eye. 



CXXXVIII. SUBCUTANEOUS METHOD. 



1. Remove the hair or feathers, wash the skin with soap and water, 

 and sterilize with corrosive sublimate solution 1 to 1000 (see 66, p. 44). 



2. For liquids use a sterilized hypodermic syringe. The skin is 

 raised with a pair of forceps, and the point of the hypodermic needle 

 inserted, and an incision made. 



3. For solid material, a pocket is made in the skin as follows : 

 Take up the skin with the forceps, make a small incision with steril- 

 ized scissors, and cut a pocket under the skin. Hold the pocket open 

 with sterilized forceps, and place the material as far back as possible 

 without touching the edges of the wound with the platinum loop or 

 KocKs needle. Earth can be introduced in this manner. 



4. Pull the wound together and allow it to remain, or cover 

 with a little iodoform collodion, or sear with a hot platinum 

 needle. During the operation the animal must be held perfectly still. 

 For the smaller animals many forms of holders are made, especially for 

 mice, which are held in proper position for inoculation at the root of 

 the tail. Guinea-pigs, rabbits, and pigeons are best held by an 

 assistant. Pigeons are generally inoculated in the pectoral muscles, 

 mice at the root of the tail, while the other animals are generally 

 inoculated in the abdominal wall, either to the right or left of the 

 median line. 



