144 PRINCIPLES OF SOIL MICROBIOLOGY 



Bacillus niger Migula 



{Bacillus lactis niger Gorini) 

 Bacillus mesentericus var. flavus 

 Bacillus panis Migula 



(Bacillus mesentericus panis viscosus Vogel) 



(Motility lost by capsule formation) 



Group III. C ohaer ens-simplex group 



Motile organisms somewhat larger than either Bacillus subtilis or Bacillus 

 mesentericus, measuring 0.37 to 0.75 by 0.75 to 3^. Thicker and longer forms on 

 glucose agar. Involution and shadow forms are common and appear early. 

 The spores are cylindrical, measuring 0.56 to 0.75 by 1 to 1.5^. A soft mass is 

 formed on solid media; turbidity with little or no scum on liquid media. 

 Bacillus cohaerens Gottheil 

 Bacillus simplex Gottheil 

 Bacillus agri Ford and associates 

 Bac. asterosporus and Bac. teres A. M. and Neide belong also to this group. 



Group IV. Mycoides group 



Large organisms with square ends growing in long chains. Single cells measure 

 0.5 by 3 to 6fi. On glucose agar, the organisms are thicker and longer and are 

 made up of globular bodies. Tendency for the organisms to grow in curves or 

 spirals. The spores are central or excentric, round or oval to cylindrical, measur- 

 ing 0.75 to 1 by 1 to 2 fi. Dry and penetrating growth on solid media; firm 

 tenacious scum on liquid media. 

 Bacillus mycoides Flugge 

 Bacillus prausnitzii Trevisan 



(Bacillus ramosus liquefaciens Prausnitz) 

 Bacillus adhaerens Ford and associates 

 (No motility) 



Group V. Cereus group 



Large, motile organisms with rounded ends, measuring 0.75 by 2.25 to 4fi. Tend 

 to grow in short chains. Thicker and longer on glucose agar, where protoplasm 

 is converted into globular bodies. Central or excentric spores, cylindrical, meas- 

 uring 0.5 to 0.75 by 1.12 to 1.5/x. Spores retain protoplasm at one or both ends, 

 often resembling enlarged subtilis or mesentericus spores. A soft pultaceous mass 

 is formed on solid media, with tendency to fold or wrinkle; thick friable scum on 

 liquid media. 



Bacillus cereus Frankland (The Bac. ellenbachensis often referred to as an 

 important soil organism belongs here). 



Bacillus albolactus Migula 



Bacillus cereus var. fluorescens Ford and associates 



Group VI. Megatherium group 



Very large, actively motile organisms, measuring 0.75 to 1.25 by 3 to 9p. Long 

 forms are often produced ; these spread out, lose their cytoplasm and show peculiar 



