ANIMAL INOCULATION IN BACTERIOLOGY 297 



alcohol to evaporate. The animal is now ready for the 

 operation. 



Note. It is understood that a 2% solution of liquor cresolis com- 

 positus (U. S. P.) shall be used wherever a disinfectant solution is indi- 

 cated unless otherwise stated. 



III. METHODS 



Where the exact nature of the inoculum is unknown, 

 the experimenter will be guided, as to what method to select, 

 by his judgment, influenced by experience with other inocula 

 in animal experimentation. The method most adaptable 

 in the case of each specific microorganism will be indicated 

 in the treatment of that organism. 



1. Cutaneous. Rub the inoculum on the shaved and 

 disinfected skin or make several parallel, superficial inci- 

 sions and rub the inoculum into the scarifications with a 

 sterile scalpel. See that no disinfectant remains on the 

 skin before operating. 



2. Subcutaneous. I. (a) Pick up the skin with the 

 thumb and forefinger of the left hand and insert the needle 

 through one side of the fold of skin thus made. 



Note. The point of the needle should not enter the skin on the 

 other side of the fold, but should lie in the subcutaneous tissue. 



(6) Release the skin and inject the material. 



(c) Place the finger moistened with the disinfectant 

 over the point where the needle enters the skin and remove 

 the needle. 



II. (a) For solid material that will not pass through a 

 hypodermic needle, make a short incision through the skin 

 parallel to the horizontal plane of the body. 



(b) With a sterile probe separate the skin from the 

 underlying tissues on the lower side of the cutaneous 

 incision, making a small pocket in the subcutaneous 

 tissue. 



(c) With fine-pointed sterile forceps insert the inoculum 



