118 VETERINARY BACTERIOLOGY 



guinea-pig or cavy; next in importance is the rabbit. Mice and 

 rats, particularly the white varieties, are sometimes used. When 

 birds are necessary, the pigeon and domestic fowl are generally 

 utilized. Some of the larger animals, as the goat or horse, are 

 used for the production of serum, where it is required in con- 

 siderable quantities, as in the manufacture of antitoxins. The 

 monkey has been used to some extent in the study of diseases 

 peculiar to man. Heifers are utilized in the preparation of the 

 vaccine against small-pox. Swine are used in the preparation of 

 hog-cholera antiserum. 



Methods of Inoculation. Animals are commonly inoculated just 

 beneath the skin or subcutaneously . The hair is shaved from the 

 area selected, the skin is washed with an antiseptic, and a hypo- 

 dermic needle inserted into the subcutaneous tissue. In the inocu- 



Fig. 64. Ear veins of a rabbit: a, Posterior vein; 6, point at which injections 

 may be most easily made; c, median vein (adapted from Frost). 



lation of a solid material a little incision may be made in the skin, 

 the material inserted, and the flaps of skin pulled together. Usu- 

 ally stitches to hold the skin are unnecessary. Intravenous 

 inoculation is accomplished by inserting the needle into a vein. 

 Usually a rabbit is selected for this purpose. Reference to Fig. 

 64 will show the vein on the posterior edge of the ear, into which 

 injections are usually made. The large median vein is not suitable, 

 as it is situated in loose connective tissue and therefore difficult 

 to enter. The posterior vein, on the other hand, is embedded in 

 firm connective tissue and cartilage, so that it does not give before 

 the needle-point. 



Intraperitoneal injection is accomplished by thrusting the 

 hypodermic needle through the abdominal wall. Some care must 

 be used not to penetrate too rapidly, as there is danger of injuring 



