60 ORIENTAL PLAGUE chap. 



could be studied in every detail. As a result it was 

 definitely ascertained that the microbe was not B. pestis, 

 but a microbe related partly to Bacillus coli and partly to 

 the Bacterium lactis aerogenes. In some of its physio- 

 logical and also in its morphological characters it re- 

 sembles to a considerable degree B. pestis ; indeed, if the 

 microbe were insufficiently examined, i.e. by these tests 

 alone, the mistake that it was B. pestis might easily 

 have been made, as will appear from the details of my 

 observations. 



From the first experimental guinea-pig, No. 1, a 

 guinea-pig, No. 2, was injected intraperitoneally with a 

 few drops of the sanguineous subcutaneous exudation, 

 while another guinea-pig, No. 3, received a similar dose 

 subcutaneously. The latter (No. 3) died within forty-eight 

 hours ; the former (No. 2), which in forty-eight hours was 

 in a dying condition, was killed. The post-mortem of the 

 subcutaneously injected guinea-pig (No. 3) was exactly 

 similar to that of guinea-pig No. 1. Guinea-pig No. 2 

 showed copious exudation in the peritoneum, and in the 

 exudation purulent nocculi and pseudomembranes. These 

 materials contained dense crowds of the same bipolar- 

 stained bacilli as in guinea-pig No. 1 ; the bacilli appeared 

 embedded in a viscid, gelatinous matrix. 



Of a single colony of an agar plate (twenty-four hours 

 old) of the peritoneal exudation of guinea-pig No. 2, a small 

 amount was injected intraperitoneally into a guinea-pig 

 No. 4. This animal was found dead in twenty hours. 

 Its post-mortem appearances showed copious viscid grey 

 exudation in the peritoneal cavity ; the spleen was small ; 

 the liver was covered with grey pseudomembranes ; both 

 lungs appeared injected ; the pleural cavity contained 



