232 SPECIAL BACTERIOLOGY 



RHIZOBIUM LEGUMINOSARUM (FRANCE.) 



Franck obtained cultures of this organism in liquefied drops of 

 gelatine under microscopic control, and also on plates. According to 

 the same author, the root bacteria occur only in the clusters (0*9 to 

 1'3 n in length), oval or rod-shaped, which later form zooglrea. The 

 gelatine is liquefied slowly. The morphology is the same in all the 

 Leguminosae. 



According to Franck one could at the most accept different varieties 

 or nutrition modifications. 



BACILLUS TUBERIGENUS (VON GONNERMANN.) 



Found in the root nodules of the lupine bean, etc. Von Gonner- 

 mann, with a specially prepared lupine peptone gelatine, isolated ten 

 different species of bacteria, two cocci, the Bacillus fluorescens non- 

 liquefaciens, and seven bacilli which the author named Bacillus tuberi- 

 genus, Nos. 1 to 7. When sterilized earth was inoculated with Nos. 3 

 and 5, the formation of typical root nodules took place. 



BACILLUS TUBERIGENUS (No. 3). 



Is motile, and 0*3 to 0'6 //. in size. 



On Gelatine. Well defined, yellowish-brown, finely granular colonies 

 develop ; the gelatine is liquefied quickly. 



On Potatoes, a bright reddish-brown coating. 



BACILLUS TUBERIGENUS (No. 5). 



Is non-motile and more slender than No. 3 (0*25 to 2 /x). 



On Gelatine it forms colonies resembling those of the Bacillus 

 anthracis, but does not give off any offshoots into the surrounding media. 



On Potatoes it forms yellow prominent drops. 



These bacilli, as well as the Bacillus radicicola, penetrate the root 

 tissue of the Leguminosae, and form in the cells irregular masses with 

 offshoots and vacuoles, and as such possess the faculty of assimilating 

 the nitrogen of the air. Entire clearness over the importance of these 

 bacteria does not yet exist, nevertheless they appear to play an import- 

 ant role in the nourishment of plants, especially the Leguminosae. 



THE NITRIFYING BACTERIA. 



According to Winogradsky the many species of nitrifying bacteria 

 can be classified into two sharply divided sub-groups, Nitroso-bacteria 

 and Nitro-bacteria. The Nitroso-bacteria oxidize ammonia to nitrous acid. 



