338 THE PRESERVATION OF HEALTH 



and of the digestive juices, and reach the intestines to 

 develop there. Still other kinds are always normally 

 present there. Immense numbers are always found in 

 the contents of the large intestine. The bile, which is 

 known to have the power of preventing putrefaction, 

 appears to be able to modify the action of the microbes and 

 to keep that action within certain limits which may render 

 it helpful to digestion. 



Taken in through a wound in the epithelium, the noxious 

 germs cause inflammation and swelling, and their toxins 

 may circulate through the body. Or by the wonderful 

 power of the white corpuscles of the blood, which feed 

 upon the bacteria in the blood, the evil may be neutralized. 

 The plasma of blood and lymph seems also to possess the 

 property of destroying certain toxins, or of protecting 

 the system from their action. 



488. Antitoxins. In recent years some marvelous dis- 

 coveries have been made respecting nature's way of coun- 

 teracting in the body the effects of certain germs of 

 disease. 



It has been shown that in the progress of certain in- 

 fectious or contagious diseases there is developed in the 

 serum of the blood or in the tissues a substance which 

 is a poison to the bacteria causing the disease, or a sub- 

 stance which neutralizes the toxins produced by them. 

 In course of time it may be days or weeks enough of 

 this substance, called antitoxin^ is manufactured to neu- 

 tralize the toxin or to destroy the germs of the particular 

 disease, and the patient recovers. In certain cases, as in 

 measles, smallpox, whooping cough, etc., this protecting 

 substance seems either to remain in the blood or to be 

 continually produced for the rest of life, giving perma- 

 nent security from the disease. In others, such as diph- 



