294 MEDICAL BACTERIOLOGY 



CHAPTER VIII 



ANIMAL INOCULATION AND STAINING OF 

 BACTERIA IN TISSUE 



EXERCISE 97. ANIMAL INOCULATION. 



METHODS OF INOCULATION. Animal inoculation is practiced to 

 determine the pathogenic properties of an organism and also the 

 character of the tissue changes produced. The animals commonly 

 used are white mice and white rats, rabbits, guinea pigs and pigeons. 

 Inoculations are usually made subcutaneously, intraperitoneally 

 or intravenously, and in special cases into the pleural cavity, brain, 

 eye, etc., etc. Mice require a holder, the inoculation being usually 

 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 material injected. 



&. For solid material a pocket is made which is stitched, or sealed 

 with contractile collodion, after the material is introduced. 



Intraperitoneal. Either liquids or solid material may be intro- 

 duced. 



a. For liquids. The seat of inoculation is prepared as above, the 

 syringe needle is then plunged directly into the peritoneal cavity. 



6. For solid material. The animal is anesthetized ; the hair is 

 clipped or shaved from a portion of the median line, about half way 

 between the pubis and the sternum ; a slit is made in the skin with 

 sterile instruments ; the smallest possible opening is made along the 

 linea alba into the peritoneal cavity and the material introduced; 

 the wound closed and the body wall and the skin stitched separately. 

 It is hardly necessary to add that the whole operation is carried out 

 under the most strict aseptic precautions. Collodion sacs are intro- 

 duced in this way. 



