CHAPTER VIII 



A PATHOGENIC BACILLUS RESEMBLING THE BACILLUS 

 OF THE GROUSE DISEASE 



In the course of the spring and summer of 189 1 I 

 found in garden earth, in very large numbers, a species 

 of bacilli which have a powerful virulent action on 

 rodents, and which, when introduced into them sub- 

 cutaneously, produce fatal infection ; their action on 

 the mouse, and to a certain lesser extent on the guinea- 

 pig, is not dissimilar to that of the grouse bacilli. In 

 cultivations in various media the bacillus presents a 

 great many points of resemblance with the bacillus 

 of grouse disease, for which it might be easily mis- 

 taken ; but the two microbes are two distinct species, 

 and therefore the occurrence in numbers of the patho- 

 genic bacillus in earth — whether it also occurs in earth 

 on the moors I am unable to say, I got it from garden 

 earth that had been manured within recent times — 

 cannot be brought in any relationship to the bacillus 

 of grouse disease. In order to obviate such a rela- 

 tionship between the two species of bacilli being 



