CHAPTER VI 

 IMMUNITY TO TOXINS 



THE mechanisms by which the injurious effects of toxin in the 

 blood and tissues are combated are exceedingly complex, and 

 may be divided roughly into two series. In the first and less 

 interesting, though perhaps not less important, the mechanism 

 may be called (for want of a better term) non-specific. It acts 

 equally on all or many toxins, and recovery from the effects of the 

 poison is not necessarily or usually followed by any immunity 

 thereto. For example, the dilatation of the vessels and accelera- 

 tion of the blood-stream which takes place in an inflamed focus 

 may be regarded as one of the natural provisions for avoiding the 

 too intense action of a toxin in one small area. The poison pro- 

 duced is rapidly swept into, and diluted by, the whole blood- 

 stream, and if not produced in large amounts may not reach any 

 tissue in amount sufficient to cause much damage. Perhaps, also, 

 the proteolytic action of the enzymes frequently produced (mainly 

 from the polynuclear leucocytes) in the inflammatory focus are of 

 some importance. Toxins are very fragile bodies, and it is ex- 

 tremely probable that the potent enzymes which occur in all fluids 

 rich in polynuclear leucocytes may bring about their destruction in 

 considerable amounts. 



The more purely chemical processes are hardly known in their 

 application to true toxins, but they have been largely studied in 

 regard to the methods by which the organism combats deleterious 

 substances produced in the course of metabolism, or absorbed 

 from the alimentary canal. The latter are for the most part 

 bacterial products, though not true toxins. It is, however, quite 

 possible that these latter substances are destroyed by the same 

 processes, which Herter classifies as (i) oxidation, (2) hydration 

 and dehydration, and (3) various syntheses. 



As an example of the process of oxidation, we may consider the 

 formation of indol, a toxic substance, which is formed by B. coli 



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