1 84 FIXATION OR ASSIMILATION OF NITROGEN 



in media or soil containing little or no combined nitrogen, 

 provided that xylose, galactose, or other carbon compounds 

 are supplied. 



The " Alinit " Bacillus (s. ellenbachensis, a, Caron) is a large 

 rod-shaped organism, which does not form very long threads as a 

 rule. Each cell has rounded ends, and is from 3 to 6 /z long 

 and 1.25 to 1.5 p thick; it is stained by Gram's method. The 

 organism is motile, and forms central oval spores, which exhibit 

 distinct polar germination, the young rod escaping from the end 

 of the spore. The optimum temperature for growth is about 

 28 to 30 C., and it is aerobic. 



Gelatine. The colonies are at first roundish, somewhat dark 

 in the centre, with radial filamentous outgrowths ; later the gela- 

 tine is liquefied. The " stab " soon shows funnel-shaped lique- 

 faction, with a pellicle on the surface and a flocculent deposit. 



Agar. Surface colonies yellowish-white, roundish or slightly 

 granular and puckered, surrounded by hair-like extensions ; deep 

 colonies with irregular thread-like projections, which resemble 

 the hyphae of fungi. 



Potato. Greyish-white growth, soft and flat. 



Milk. Milk is coagulated, and becomes alkaline, with a 

 surface scum ; the precipitated casein is peptonized and slowly 

 dissolved. 



3. An aerobic spore-forming bacterium capable of 

 assimilating free nitrogen was isolated from the soil around 

 the nodules of Vicia villosa and other leguminous plants 

 by Lohnis and Westerman ; they named it Bact. danicus. 

 It is very variable in form and size, appearing in mannite 

 solutions as a large coccus or as a rod 3 to 5 [* long and 

 i p thick. On mannite-agar it produces spores some- 

 times in " clostridial " cells, the colonies on this medium 

 being round, shining greyish-white 2 to 4 mm. in diameter 

 in five days at 20 C. 



