HEALTH AXD DISEASE 415 



counteracts, or acts against, the toxin so as to render 

 it harmless. Each disease probably has its own anti- 

 toxin. If this is produced rapidly and abundantly 

 enough, the toxin of any disease is destroyed, the cof- 

 puscles then dispose of the germs, and there is imme- 

 diate recovery from the disease. 



If the body is kept in good healthy condition by the 

 proper food, exercise, and plenty of fresh air and 

 sleep, there is usually an abundance of white corpus- 

 cles to defend it against germs. It is also in the proper 

 condition to produce the right germicides or antitoxins, 

 and thus render it less subject to infectious diseases. 



Treatment of disease. To cure an infectious disease 

 it is necessary to destroy the germs which produce it. 

 The power to do this lies mostly in the body itself. 

 If it becomes impossible for the body to accomplish 

 this, however, other means must be resorted to. Chief 

 of these are serums, vaccines, and drugs which we call 

 medicines. 



Serums are obtained from the blood of an animal, 

 usually a horse. They are prepared in the following 

 manner : dead or weakened germs, or the toxins of the 

 diseases to be cured, are injected into the blood of the 

 horse. "We still have much to learn in regard to the 

 substances which these then produce in the blood of 

 the animal. Extracts, called serums, are made from 

 the blood drawn from an animal treated in this way. 

 "We do know, however, that if such serums are injected 

 into a person, substances are produced which result 



