126 BACTERIOLOGY OF THE SOIL 



present in soil. It is a large bacillus, 5 to 20 //. long, 1.5 to 2 & 

 broad, sometimes slightly bent and united in chains ; the ends 

 are not rounded. 



It moves with a somewhat sluggish motion, is aerobic, and 

 produces large spores, 2 to 2.7 ^ long and i & broad, which 

 exhibit polar and equatorial germination. 



Stained by Gram's method. 



Gelatine. The colonies are round at first, later kidney- 

 shaped, generally without the fringed edge so frequently seen in 

 Bs. subtilis. The medium is liquefied. 



The stab shows tube-like liquefaction, the liquid being turbid. 



Agar. Greyish elevated colonies, somewhat granular, with 

 short ramifications round the edges, capable of being drawn into 

 threads, and more slimy than those of Bs. subtilis. 



Potato. Like Bs. subtilis, but usually yellower and more 

 mealy. 



Bouillon is made turbid. 



Milk. Curd precipitated with very slight acid reaction at 

 first ; later slightly alkaline with little peptonization of the casein ; 

 no pellicle is formed. 



Nitrate bouillon. The nitrates are not reduced, and no pellicle 

 is formed. 



Bs. ellenbachensis, a, Caron. The " Alinit-bacillus " (see 

 p. 183). The bacillus closely resembles B. megatherium, and 

 according to some authorities is a form or variety of this organism. 

 It is rod- shaped, 3 to 6 ju long, 1.25 to 1.5 /* broad, often single 

 or united in pairs. Few or no long chains are formed. It is 

 motile, produces spores which germinate at the poles, and is 

 stained by Gram's method. Its behaviour on the various media 

 is very similar to that of Bs* subtilis. 



Bacillus vulgatus, or Bs. mesentericus vulgatus, Fliigge. 

 This organism is ordinarily termed the "potato bacillus," growths 

 of it being frequently found on imperfectly sterilized potato 

 slices. It is a common soil bacteruim, usually shorter and more 

 slender than B. subtilis, being 2 to 7 p long and .8 p broad, 



