2 OMENTAL PLAGUE chap. 



contagion, relegated all the above states to their proper 

 place, viz. as being of the nature of secondary causes, and 

 therefore of secondary importance. 



Yersin {Annates de V Institute Pasteur, viii. p. 662), 

 and Kitasato {Lancet, 1894, ii. p. 428) showed that in all 

 cases of bubonic plague the buboes, the spleen (and also 

 the blood) contain in very large numbers minute bacilli, 

 which in morphological and cultural respects possess 

 definite characters ; that a trace of culture of the microbe 

 inoculated into a rodent causes invariably the typical acute 

 fatal disease, bubonic plague, with the same copious multi- 

 plication of the same bacillus. These statements are easy 

 of verification, and there can therefore remain no doubt 

 that all postulates which a microbe has to fulfil in order 

 to be regarded as specifically the causa causans has been 

 complied with in the case of B. pestis. Moreover, the 

 numerous cases of plague in man which, from time to 

 time, have come under the notice of a large number of 

 observers in various countries, in which plague has appeared 

 since 1894, and the numerous rats dead in various plague- 

 stricken countries that have been subjected to bacteriologi- 

 cal examination, have all yielded the same result, viz. the 

 inflamed lymph glands, the spleen, and other organs 

 teemed with the same B. pestis. This bacillus, as will be 

 shown, is a well-characterised species — well characterised 

 in morphology, in culture, and by experiment — so much so, 

 that it has become an established fact that the identifica- 

 tion in the glands, spleen, or other organs of any body is 

 proof positive that that body is subject to and affected 

 with Oriental plague. 



Kitasato's earlier and later accounts of the B. pestis 

 differ somewhat from the description given by Yersin, 



