CHAPTEK IV 



MICROBES SIMULATING IN ONE OR ANOTHER RESPECT 

 THE B. PESTIS 



Although the B. pestis is, in respect of its morphological, 

 cultural, and experimental characters, a well-defined species, 

 and not easily overlooked or mistaken, yet there are in the 

 nature of things occasions when either in cases of man 

 under suspicion of plague, or in cases of rats dead under 

 suspicious circumstances — in docks, on board ship, in 

 houses and localities open to invasion or actually invaded 

 by plague, — correct bacterioscopic diagnosis might be for 

 one reason or another difficult, or, owing to inexperience of 

 the analyst, might not be forthcoming. And for this reason 

 we shall presently show there are microbic species which, 

 in their pathogenic effect on some test animals, e.g. the 

 guinea-pig, simulate plague ; or in their morphological and 

 staining characters are not easy to distinguish from the 

 true B. pestis, e.g. B. proteus or B. coli and other 

 similar microbes ; or which in morphology and certain 

 cultural characters bear a certain resemblance to B. pestis. 

 Add to this that these simulating species may be found in 

 man or in the rat under suspicious circumstances — that is, 

 under circumstances which do not exclude plague — and no 



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