56 OEIENTAL PLAGUE chap. 



agar plates the characteristic circumscribed small watery- 

 raised colonies, composed of non-motile bacilli, and when 

 inoculated cutaneously into mice, rats, or guinea-pigs, will 

 produce the appearances and fatal results of plague. Sub- 

 cutaneously injected into the guinea-pig the B. pestis 

 produces marked swelling and inflammation of the 

 lymphatic gland themselves, not merely a subcutaneous 

 infiltration ; after death the spleen is crowded with the non- 

 motile, Gram-negative, bipolar bacilli. Proteus vulgaris, 

 however virulent otherwise, when inoculated cutaneously 

 into guinea-pigs, mice, or rats, produces no effect. 



The frequent occurrence of virulent Proteus vulgaris — 

 that is, virulent on subcutaneous injection of fair amounts 

 into the groin of the guinea-pig — particularly in the spleen 

 of rats, in the lung of man some time after death (in the 

 warm season in less than twenty -four hours), as also in 

 the fluid of the mouth, and therefore in the expectoration, 

 has to be carefully borne in mind. These microbes show, 

 in properly stained film specimens, more or less marked 

 bipolar staining ; wherefore, to make diagnosis by a mere 

 stained film specimen is to be seriously avoided in such 

 cases. 



2. B. coli. — Next in importance are the pathogenic 

 varieties of B. coli, or at any rate the microbic species 

 which, by their general characters, belong to the group of 

 B. coli and allies — that is, bacillary species which do not 

 liquefy gelatine, which are Gram-negative, which ferment 

 glucose (and some other sugars), which in surface plate 

 cultivations (gelatine, agar) exhibit the character of colonies 

 of B. coli and coli -like microbes, viz. rapidly growing, flat, 

 dry, angular, grey expansions on gelatine, their bacilli motile. 

 Obtained from diseased tissues — sputum, cystitis, perito- 



