CHAPTER VIII. 

 TOXIN AND ANTITOXIN (continued). 



DEFINITION OF TOXIN, TETANUS TOXIN, BOTULISM TOXIN, DYSENTERY TOXIN, 



STAPHYLOLYSIN. 



The diphtheria toxin and its antitoxin just discussed in detail is of great 

 practical and theoretical importance, and can serve as a type of all true toxins 

 and antitoxins. Bacterial toxins can be defined as poisons given off by the bac- 

 teria, the symptoms resulting from their action appearing after a certain incuba- 

 tion period. The invaded organism reacts by the production of specific anti- 

 toxins which neutralize the toxins in amounts, following the law of multiple 

 proportions. 



Further analysis of this definition indicates that a substance can be con- 

 sidered a toxin only when it has a poisonous action, or in the words of 

 Ehrlich when it possesses a toxophore group . 



This toxicity does not always manifest itself by necrosis or death as in 

 diphtheria. More frequently the toxin has a somewhat selective action 

 affecting a certain group of organs. Thus a toxin acting upon the central 

 nervous system or blood is designated respectively as a neurotoxin or a 

 hemotoxin. To differentiate a true toxin from other poisonous products 

 obtained from bacteria, it is important to note that all true toxins are 

 elements of secretion of the living bacteria, and can be separated from them 

 by filtration. According to this definition poisons contained within the bac- 

 terial bodies themselves, which may be liberated by various mechanical, 

 physical, or chemical means, cannot be considered as belonging to the 

 class of true toxins. These poisons are characterized by peculiar proper- 

 ties and are known as endotoxins. In addition it may be remarked that 

 inasmuch as a true toxin requires, a period of incubation in order to mani- 

 fest its action, those toxins which act spontaneously are to be excluded from 

 the former group. R. Krause nevertheless considered some of the poisons 

 isolated from the cholera and cholera-like spirilla (El Tor Vibrio) as true 

 toxins even though they lack an incubation period. 



The real essential property of a toxin is doubtlessly that one can immu- 

 nize against it, and be able to demonstrate the presence of antitoxins within 

 the serum of the immunized animal. Ehrlich furthermore claims that the 

 amount of antitoxin produced follows the law of multiple proportions. By 



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