546 BACTERIOLOGY. 



FORMATION OF TOXIN BY BACTERIA. The num- 

 ber of bacteria which are capable of producing a true 

 toxin is quite small. Of those that are concerned in 

 human pathology, diphtheria and tetanus organisms are 

 the most important. For the majority of the other bac- 

 teria toxin formation has not been definitely demon- 

 strated. In most of the other pathogenic bacteria it 

 has been ascertained that the toxic action which they 

 bring about rests upon the poisonous character of the 

 bacterial protoplasm, and we now regard the toxic action 

 of these bacteria to be clue to the formation of endotoxins 

 or intracellular toxins. 



THE ENDOTOXINS. In contradistinction to the re- 

 sults obtained in the injection of the soluble toxins the 

 action of the endotoxins is not nearly as well understood. 

 The injection of the endotoxins does not bring about the 

 formation of anti-endotoxic substances in the serum. 

 The serum of animals treated with the endotoxins has 

 merely an increased bactericidal action, and through the 

 disintegration of the bacteria this induced protection 

 against infection is seen, but multiple doses of serum 

 from such animals do not act against corresponding 

 multiple doses of endotoxin, as is the case with true toxins 

 and their antidotes, antitoxins. The treatment of ani- 

 mals with endotoxin does not protect the animal body 

 against the action of the endotoxius. 



The endotoxins are not secreted or excreted in the 

 culture media in which the bacteria are cultivated, as are 

 the toxins, but are associated with the bacterial cells, 

 and are only liberated through the solution of the bac- 

 teria that is, through bacteriolysis. 



TOXOIDS AND TOXONES. It is important to note 



