CHAPTER VI

NATURAL IMMUNITY AGAINST PATHOGENIC MICRO-ORGANISMS 128 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 _Trypanosomata_ in the refractory organism.