144 



NON-PATHOGENIC BACTERIA. 



root or "wurzel" bacillus. It is found in water and in 

 the upper layers of the soil. It is a large, thick bacillus, 

 with rounded ends, not flagellated and but slightly motile. 

 It frequently, in culture, forms long chains or threads, and 

 usually contains a central spore. It is a facultative anaerobe, 

 with strong aerobic tendencies, growing rapidly at the room 

 temperature with liquefaction of the gelatin. It is stained 

 with all the anilin dyes, including Gram's. 



It forms a thin whitish growth, con- 

 FIG. 53. si sting of a very dense network of fine 



freely interlacing threads. The growth 

 resembles the gnarled roots of an old tree 

 radiating from a common centre, from 

 which it derives its name of root bacillus 

 (Figs. 53 and 54). The growth on agar 

 is very characteristic. 



FIG. 54. 



Bacillus mycoidee. 



Bacillus fluorescens liquefaciens : Found in water and 

 putrefying liquids ; occasionally in the conjunctival sac. It 

 is a very small actively motile rod, containing no spores. It 

 has numerous flagella. It is strongly aerobic, and grows 

 rapidly on all ordinary media at the room temperature with 

 liquefaction of the gelatin. It is easily stained with the 

 ordinary dyes. It forms a fluorescent, greenish-yellow pig- 

 ment on all media except the potato, on which the growth is 



