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[136] CHAPTER VI 



NATURAL IMMUNITY AGAINST PATHOGENIC 

 MICRO-ORGANISMS 



Natural immunity and the composition of the body fluids. — Cultivation of the 

 bacteria of influenza and pleuro- pneumonia in the fluids of refractory animals. — 

 Resistance of Daphniae to the Blastomycetes. — Examples of natural immunity 

 in Insects and Mollusca. — Immunity of Fishes against the anthrax bacillus. — 

 Immunity of frogs against anthrax, Ernst's bacillus, the bacillus of mouse 

 septicaemia and the cholera vibrio. — Natural immunity in the cayman. — 

 Immunity of the fowl and pigeon against anthrax and human tuberculosis. — 

 Immunity of the dog and rat against the anthrax bacillus. — Immunity of 

 Mammals against anthrax vaccines. — Immunity of the guinea-pig against 

 spirilla, vibrios, and streptococci. — Natural immunity against anaerobic bacilli. 

 — Fate of Blastomycetes and Trypanosomae in the refractory organism. 



In the third chapter reference has been made to the frequency of 

 cases of natural immunity against infective diseases. Examples of this 

 immunity occur in the lower animals — the Invertebrata — and are 

 widely met with among the Vertebrata. We have already mentioned 

 that this natural immunity can be attributed neither to insuscepti- 

 bility to microbial toxins nor to the elimination of the micro- 

 organisms by the excretory channels. Nevertheless the pathogenic 

 . agents which have penetrated into the tissues of the refractory 

 organism disappear, without being eliminated. To facilitate the 

 study of their disappearance it has been necessary to pass in review 

 the phenomena that follow the introduction of foreign bodies into 

 the organism and to present a brief analysis of the process of re- 

 sorption of cell elements in its relations to digestion. We have tried 

 to demonstrate that resorption is nothing more than a process of 

 digestion which, instead of going on in the intestinal canal, takes place 

 in the tissues ; that it is, indeed, an intracellular digestion exactly 

 comparable to that which serves for the nutrition of certain of the 

 lower animals. 



