VII GENERAL CONSIDERATIONS 6i 



which is not only accidentally present in the grouse 

 disease, and which most certainly is not of the nature 

 of a harmless saprophyte, but which possesses a 

 definite causative relation to it. 



This bacillus belongs to a group of pathogenic 

 bacilli which have certain important characters in 

 common, but which, owing to certain other import- 

 ant distinguishing characters, both in culture and 

 in physiological action, represent several definite 

 species. This group of bacilli comprises : 



The bacillus of fowl cholera, the bacillus of fowl 

 enteritis, the bacillus of duck cholera, the bacillus 

 of the Middlesbrough pneumonia, the aerobic bacillus 

 of malignant oedema described by me, the bacillus 

 of Frettchenseuche, the bacillus of Wildseuche, the 

 bacillus of swine -plague of the Germans, the bacillus 

 of English swine -fever and American hog cholera. 

 All these bacilli are morphologically similar ; they 

 are oval in shape, single, but chiefly in dumb-bells ; 

 amongst them are rods and even cylinders, single or 

 in dumb-bells, some motile, others non- motile; they 

 are aerobic, they do not liquefy the gelatine, they 

 grow in a similar but not identical way in gelatine, 

 in plate, streak, and stab culture, but they show con- 

 siderable and definite differences as regards rapidity 

 of growth ; they produce in rodents an acute fatal 

 disease which, generally speaking, partakes of the 



