. CHAPTER VIII. 
ANIMAL INOCULATION AND STAINING OF BACTERIA IN TISSUE. 
EXERCISE Cill. ANISLAL INOCULATION. 
MeEtTHops 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 used 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 
eollodion, 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. 
—— pneumonicum. Mice and young rats, intraperitoneal. 
tuberculosis. Guinea pigs, rabbits and field mice, any method of inoculation 
will produce the disease. 
