CHAPTER XVIII. 



BACTERIACEAE. 



GENUS BACILLUS AND ITS SPECIES PATHOGENIC FOR 



ANIMALS. 



General discussion of the genus. The genus Bacillus was 

 originally introduced by Cohn. 1 The name bacillus has been 

 used with different meanings in various classifications. 

 Fischer 2 includes under it non-motile rod-shaped organisms 

 with or without spores. Lehmann and Neumann 3 include in 

 it rod-shaped organisms that form endospores centrally located 

 without bulging, regardless of their motility. Migula 4 in- 

 cludes in this genus all rod-shaped, motile bacteria with peri- 

 trichic flagella. The genus is often loosely employed to 

 designate all rod-shaped bacteria regardless of their flagella 

 or motility. 



As defined by Migula, there are about nine hundred spe- 

 cies of the genus Bacillus described, of which there are about 

 twenty that are known to be pathogenic for domesticated 

 animals. The species of this genus are widely distributed in 

 nature and in certain instances it is difficult to fix differential 

 specific or varietal characters. We have included a brief de- 

 scription of a very few of the more commonly encountered 

 non-pathogenic bacilli such as Bacillus subtilis, B. vulgaris and 

 B. prodigiosus. 



'Cohn. Beitrage zur Biologie der Pflanzen, Bd. I (1872) p. 174. 



2 Fischer, loc. cit. 



3 Lehmann and Neumann. Atlas and Principles of Bacteriology, 

 1901. 



4 Migula. loc. cit. 



