282 SWINE 



produce a fatal case of hog cholera. Thus by injecting the 

 virulent hog cholera serum on one side of the hog, and 

 the protective serum from a hyper-immunized hog on the 

 other side, the hog is rendered immune. This immunity 

 is much greater than in the case v/here the serum alone is 

 used, and lasts for a much longer time. Where by sim- 

 ple inoculation with the serum the hog is rendered im- 

 mune for several weeks, if he is inoculated by the serum 

 simultaneous method he will be rendered immune for 

 several months, and possibly a great deal longer. Such 

 immunity is thought to be permanent in some instances. 

 As just outlined it will be seen that this is a process 

 of vaccination. By inoculating according to the simple 

 method where the serum from an immune hog is used 

 alone, it will have the germs or whatever else the virus 

 may be, that cause the disease, but in such an attenuated 

 form that it will render the hog but slightly immune. By 

 the serum simultaneous process where the virulent hog 

 cholera serum is injected into one side, and the protective 

 serum from the hyper-immunized hog on the other side, 

 the properties of the latter will conteract the virulence 

 of the disease germs of the former, thus producing the 

 disease in a mild form, but not sufficiently virulent to be 

 fatal, and at the same time developing in the hog pro- 

 tective means by which it can resist future attacks of 

 this virus. 



Curative Properties of the Serum. — So far as is known 

 at the present time, the serum has no curative properties 

 whatever. That is, after a hog shows symptoms of the 

 disease known as hog cholera, he cannot be saved, unless 

 he would live through the disease anyway, by being inoc- 

 ulated with this hog cholera serum. However, the pro- 

 tective properties of the serum may be used to advantage 



