72 ORIENTAL PLAGUE chap. 



cultures of one and the same bacillus, as also did the 

 blood of the heart. 



The companion rat died eighteen days later, and on 

 post mortem showed precisely the same pathological con- 

 dition and the same bacteria. 



As far as the morphological characters were concerned, 

 the bacterium in question appeared identical with Klebs- 

 Loffler's Bacillus diphtheria, not only in regard of 

 shape and non-motility, but also as regards staining 

 characters. The microbe stains well by Gram's method ; 

 indeed gives positive Neisser staining ; and shows, as 

 mentioned already, distinct metachromatism in methyl- 

 blue staining. Culturally, also, it resembles the diph- 

 theria bacillus : on agar, on gelatine, on serum, and in 

 broth the character of the growth is very much the 

 same in both cases ; like the diphtheria bacillus this 

 microbe produces acid reaction in glucose broth. As 

 regards its effect on animals, it is distinctly pathogenic 

 for rats and for guinea-pigs. In both these animals it 

 causes on subcutaneous injection a local tumour. Sub- 

 cutaneous injection into the groin of a small or large 

 dose of culture causes the formation of a gradually en- 

 larging firm tumour, which in the course of ten to twelve 

 days attains a very considerable size. The fate of the 

 tumour is either a gradual resolution and absorption, or 

 it becomes converted into an abscess which contains 

 thick pus. In either case complete recovery takes place. 

 The tissue of the tumour, and the pus of the abscess at 

 all stages, contain the bacilli in abundance. I have not 

 been able hitherto to produce any but a local result, be 

 the injected dose small or large. Several other rats 

 dead since with the same lung disease due to the same 



