CHAPTER VI 



CHEMISTRY OF IMMUNITY AGAINST BACTERIA 

 AND THEIR PRODUCTS, AND THE REACTIONS 

 OF AGGLUTINATION AND PRECIPITATION 1 



BY the application of chemical principles to the problems 

 of immunity, Ehrlich developed a hypothesis concerning the 

 nature of the action of bacterial toxins upon the cells, and 

 of the process of antitoxin formation, which has served most 

 successfully as a working hypothesis. The true toxins are of 

 so labile a nature, so readily destroyed by chemical agencies, 

 and so elusive of isolation, that their chemical natures and 

 properties remain quite unknown, and they can be detected 

 only by their biological action. Against other sorts of poisons 

 with simpler composition the animal body does not develop an 

 immunity in the same sense that it does against bacterial and 

 similar poisons, and so in studying the reactions of immunity 

 we cannot have the advantage of having at least one of the 

 factors a substance of known chemical nature. By immuniza- 

 tion or habituation a certain degree of resistance can be obtained 

 against some alkaloidal poisons, e. g., morphine, but it is not 

 of the same nature as the immunity against bacterial toxins, for 

 the blood-serum does not acquire any substances capable of 

 neutralizing the poisons. The resistance against such poisons 

 must, therefore, be considered apart from the question of 

 immunity against bacterial infection (see Chapter vii) ; but 

 with the latter may be included the consideration of immunity 

 artificially developed in the body against foreign proteids, tissues, 

 and cells. 



Immunity against bacteria may be divided into several sub- 

 jects, namely, immunity against bacterial toxins, against bacterial 

 proteids and enzymes, and against the bacteria themselves, 

 including the phenomenon of agglutination. The products 



and Serum Therapy" by Kicketts, Chicago, 1906. For bibliography see 

 Kolle and Wassermann, 1903, Bd. 4. Later references of importance have 

 been cited in the foot-notes of this chapter. 



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