84 ACTIVITIES OF BACTERIA. 



and is non-motile. From the various families of legumi- 

 noses various forms of bacteria are obtained, whose mor- 

 phologic differences, so far as generally definitely proved, 

 appear very slight. Yet every race of bacterium is espe- 

 cially adapted to one family of leguminose, and not every 

 race is able to cause tubercle formation on every family of 

 leguminose. There are, however, ' ' neutral ' ' tubercle- 

 forming bacteria free in the soil, esijecially adapted to no 

 family of leguminose and able to produce tubercle forma- 

 tion in very different families of leguminoses. ^ 



With the aid of these root-tubercles which are due to 

 the immigration of the root-bacteria, the leguminosse are 

 capable of thriving upon relatively sterile soil very poor 

 in nitrogen. The bacteria increase in the tubercle and 

 assume bizarre forms, forked, star-shaped, etc., then die 

 out and are absorbed, the plant thus receiving the benefit 

 of the nitrogenous contents of the tubercle. If one ploughs 

 the luxuriantly growing legumines (lupines) into sandy 

 soil (green manuring), the latter is generally so enriched 

 with nitrogen that plants can now thrive that are depen- 

 dent upon the store of nitrogen in the soil (wheat, etc.). 

 Consult Stutzer regarding the question of formation of 

 tubercles (C. B. L. i, 68; ii, 650 and 665). 



Maze (A. P., 1897, No. 1, 44) has undoubtedly shown 

 that nitrogpu is also assimilated by pure cultures of bacteria 

 (infusion of beans, 2% cane-sugar, 1% chlorid of sodium, 

 15% gelatin) accompanied by great consumption of sugar, 

 and also in fluids poor in nitrogen containing 2.6% of sugar. 

 The free passage of air over the culture is very important. 



For a long time cultures of tbe bacteria of legume-tubercles have 

 been sold for the fertilization of soils poor in bacteria and nitrogen, 

 but with sufficient mineral constituents, under the name " nitragen." 

 (Compare WoUny, Vierte Sitzung des haver. Landwirtschaftsrats, 

 1898, Heft II.) /Recently a preparation known as " alinit " has been 

 advocated to increase the yield of wheat. It is a dried potato preparar 

 tion, which is impregnated with very abundant spores of the so-called 

 Bacillus Ellenbachensis, identical, according to Lauck, with the 

 Bacillus subtilis, or, more properly, according to Stoklasa, with the 



' Regarding this point, lately defended especially by Nobbe and his 

 pupils, it must he mentioned that other authors, as, for example, Gon- 

 nermann, maintain a specific difference for the various tubercle-produc- 

 ing bacteria. As we have made no original investigations in the 

 matter, we desist from further details. 



