CH. ix.] BACILLUS. 97 



the single bacilli and short chains, but also in an eminent 

 degree with the elements of a bacillus-filament or leptothrix. 

 In each case, indeed, it is possible to ascertain that all 

 lengths occur from the cubical or spherical element to the 

 cylinder or rod. The former elongate into the latter and 

 then divide. According to whether the division occurs in a 

 short or long element, the daughter elements are cubical or 

 spherical in the former, cylindrical or rod-shaped in the 



/N, 



FIG. 40. BACILLUS SUBTILIS GROWN IN PORK BROTH. 



At i, the elements are thickened. The preparation had been dried and stained with 

 aniline purple. 



latter case. This applies to single bacilli, to short chains, 

 and to the leptothrix forms. 



Tnere are a great many species of bacilli, differing from 

 one another (a) in the shape of the elements, (b] in motility, 

 (c) in the power of forming filaments or leptothrix, and 

 particularly (d) in the thickness and length of the elements. 



(a) There are some species of bacilli e.g. hay-bacillus, 

 anthrax-bacillus, bacillus of putrid blood, bacillus found 



H 



