PEACTICE OF MEDICINE AND HYGIENE 



able for them; they, veritably, perish in their 

 own excretions. 



The fight goes on so long as the body has 

 vitality ; and the end of most infective diseases 

 comes when the body has become sufficiently 

 overwhelmed with toxic products to result in 

 destruction of the invading parasites. In many 

 diseases, so well balanced are the vital powers 

 of the human body, these phenomena require 

 a certain specific time for each variety of in- 

 fection. The parasites multiply until they have 

 produced an amount of toxin sufficient for 

 their own destruction; then the symptoms be- 

 gin to subside and recovery takes place. The 

 presence of these products in the blood causes 

 an immunity against the bacteria which pro- 

 duce them. In the case of some bacteria it 

 lasts for a lifetime. The development of this 

 immunity by the body saves the human race 

 from extinction. 



The knowledge of infection and inflamma- Experi- 

 tion was once a matter of vague theory and mental 

 dealt with "miasms," "humors" and 'Vital methods, 

 spirit." Now the microscope, the development 

 of the science of bacteriology, and the applica- 

 tion of these two to animal experimentation 

 have given us the positive information of these 



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