THE INOCULATION OF ANIMALS AND THEIR STUDY. 85 



CHAPTER VI. 



THE INOCULATION OF ANIMALS AND THEIR STUDY. 



THE INOCULATION OF ANIMALS. 



ITS purposes are to differentiate between bacteria. In order 

 to study their virulence it is often necessary to test their action 

 on animals. 



In the laboratory the smaller animals, such as mice, rats, 

 guinea-pigs, and rabbits, are chiefly used. 



Technic. The inoculation is made in a number of ways, 

 depending on the species of the bacteria, the nature of its 

 toxin, and the rapidity of action desired. 



The Various Methods of Inoculation of Animals. 



1. Sometimes, though rarely, the inoculation is made by 

 rubbing a solid or liquid culture over the abraded epidermis, 

 very much in the same manner as vaccine is introduced into 

 the human subject. 



2. Subcutaneous inoculation that is, into the connective 

 tissue under the skin is an important method. For this 

 purpose the hair is shaved from part of the back or abdomen, 

 the skin well washed and disinfected as well as it may be, 

 with a 5 per cent, carbolic acid solution. Then the skin is 

 seized with a pair of sterilized forceps, and with a sterilized 

 scalpel a small nick is made into it, after which a small 

 sterilized pair of scissors is introduced in the areolar tissue 

 and a pocket made for some little distance into this tissue. 

 Into this pocket the inoculating material or bacterial culture 

 (especially when a solid culture has been employed) is intro- 

 duced, by means of a sterilized forceps or a platinum loop, 

 care being taken to avoid touching the edges of the wound with 

 the instrument. 



If a liquid culture is being used, particularly in appreciable 

 quantity, it may be introduced subcutaneously by means of a 

 hypodermatic syringe and needle well sterilized beforehand. 



