SUMMARY OF SERUM MANUFACTURE 363 



it must be through the action of the serum which was injected at 

 the same time as a protective agent. 



With a potent serum these 4 pigs should all come through 

 aUve. In the 2 that received the dose of 30 c.c. of serum there 

 should not even be signs of sickness. In those that receive the 15- 

 c.c. dose of serum there may be seen some very mild symptoms of 

 the disease. In these cases, then, we have a very good example of 

 what these antibodies in the serum are capable of. Here, with an 

 injection of only a few cubic centimeters of the highly protective 

 fluid, we are able to save the life of the pig from an injection of 

 double the usual fatal amount of virus. This is the basis which 

 underlies the use of the double or simultaneous method of treat- 

 ment. 



The germs introduced with the virus and the antibodies carried 

 by the serum wage a merry warfare in the body of the hog, and the 

 result is not only a victory for the body, but the cells of that body 

 are taught a new principle in defense. The antibodies introduced 

 with the serum, seeing the need for more of their kind, quickly 

 educate the cells of the body to manufacture antibodies for ser- 

 vice in the battle for life. Once having learned the art of antibody 

 manufacture, the cells forever retain this ability. This keeps a 

 constant supply of the germ destroyers in the blood-stream, and 

 leaves the hog with a permanent protective power or immunity to 

 hog-cholera. 



The 4 pigs that were injected with virus alone and receive 

 no serum are intended as a check on the experiment, and are, ac- 

 cordingly, named "check pigs." The object of injection of these 

 4 pigs is to test whether or not the virus blood used really has 

 any power of producing disease. If this was not done it could not 

 be said positively whether the pigs given serum and virus would 

 have become sick or not. Maybe they would not have been in- 

 jured by the virus even if given no protective serum. This is 

 conclusively disproved by the results in the check pigs. These 

 checks are given only one-half the dose of the same virus, and yet 

 they will be found to drop off feed about the evening of the fifth or 

 sixth day. The effects of the virus when unchecked by serum are 

 now shown. 



In serum plants these check pigs are usually killed as soon as 



