CHAPTER VIII. 



ANIMAL INOCULATION AND STAINING OF BACTERIA IN TISSUE. 



EXERCISE CIII. ANiriAL INOCULATION. 



METHODS OF INOCULATION. Animal inoculation is practiced to determine the path- 

 ogenic properties of an organism and also the character of the tissue changes produced. 

 The animals commonly iised are white mice and rats, rabbits, guinea pigs and pigeons. 

 Inoculations are usually made intraperitoneally, intravenously or subcutaneously, and 

 in special cases into the pleural cavity, brain, eye, etc., etc. Mice require a holder, the 

 inoculation being made at the root of the tail. Other animals can usually be held by an 

 assistant. 



Subcutaneous. The place selected is usually the abdominal wall. Pigeons are 

 inoculated in the pectoral muscles; the hair or feathers should be removed and the skin 

 washed with a disinfectant, e. g. , 5% carbolic acid. 



a. For liquids a sterilized hypodermic syringe is used. A fold of the skin is raised, 

 the needle of the syringe inserted and the requisite amount of culture injected. 



b. For solid material a pocket is made which is stitched, or sealed with contractile 

 collodion, after the material is introduced. 



Intraperitoneal. Prepare seat of inoculation as above, then plunge needle directly 

 into the peritoneal cavity. 



Intravenous. A rabbit is generally chosen for this purpose and the inoculation made 

 into the dorsal vein of the ear. Slight pressure at the base of the ear will render the 

 vein more prominent. Avoid the introduction of air, which causes immediate death, and 

 keep the animals under close observation for one hour. 



Inoculation into Lymphatic system. Fluid cultures or suspensions of bacteria can 

 be injected into the lymphatics by way of the testicles, by plunging the point of the 

 needle into the substance of the testicle and injecting the desired amount of fluid- 



Inoculation into the Pleural Cavity. Where necessary the needle is introduced into 

 the pleural cavity between the ribs. It is very difficult to perform this experiment with- 

 out injuring the lung. 



Inoculation into the Anterior Chamber of the eye. Rarely practiced. The eye is 

 treated with a few drops of cocaine (2 % solution) and then the needle is inserted 

 through the cornea just in front of its junction with the sclerotic, the needle passing 

 into the anterior chamber in a plane parallel to the plane of the iris. 



The following inoculations are those most frequently made: 



Streptococcus pyogenes. Mice or rabbits, intravenous. 



Sarcina tetragena. Guinea pigs and white mice, subcutaneous- 

 Bacterium anthracis. Guinea pigs or rabbits, subcutaneous. 



pneumoniae. Rabbits and mice, subcutaneous. 



- pnewmonicum. Mice and young rats, intraperitoneal. 



tuberculosis. Guinea pigs, rabbits and field mice, any method of inoculation 



will produce the disease. 



