CHAPTER XIV 

 ANTITOXINS AND RELATED ANTIBODIES 



(Antibodies of Ehrlich's First Order) 



Toxins. The word toxin has been used with a considerable 

 variety of meanings. A substance is said to be toxic when it 

 brings about an abnormal condition when introduced into the 

 body. The discovery that certain microorganisms, particularly 

 bacteria, produced their harmful effects by means of the poisons 

 which they excreted led to the use of the term toxin to include all 

 poisons produced by bacteria. Further study demonstrated that 

 these bacterial poisons differed considerably in their method 

 of action and in other characters. Ehrlich first clearly differen- 

 tiated the bacterial poisons and used the name toxin to indicate 

 a definite type. The name endotoxin is used to designate certain 

 poisonous substances that are contained within the protoplasm 

 of the cell, and are not excreted as are the true toxins. Some 

 authors have included all these poisonous substances produced 

 by bacteria under the name toxine, and recognize toxin as used in 

 Ehrlich's sense. 



Characteristics of a Toxin (Ehrlich). According to Ehrlich, 

 the toxins constitute a group of substances having the following 

 - characteristics : 



1. The true toxins are labile, that is, they are easily destroyed 

 by heat, by acids, by exposure to light and air. 



2. The chemical nature of the toxins, with one possible excep- 

 tion, is not understood. Beyond the fact that they are organic 

 in origin and usually give some of the protein reactions, little is 

 known of their chemistry. 



3. Biological tests (i. e., animal inoculations) have been found 

 to be the only tests by which the toxins may be recognized and 

 studied. These animal inoculations, as has been before stated, 

 are quite as essential in determining the character and strength 



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