88 Physics of the Soil. 



in wnat has been named symbiotic relations. There are 

 other forms of bacteria which live upon the bean, pea, lu- 

 pine and other members of this family, also having the 

 power of fixing free nitrogen from the soil-air in forms 

 available to higher plants. 



It is known that other forms of bacteria live in symbiotic 

 relation with soil algae and in this way increase the sup- 

 ply of soil nitrogen as shown by Frank, Schlosing, Jr., and 

 Laurent in 1891, followed by Kosswitsch in 1894; and the 

 great demands for the fixing of free nitrogen to make good 

 the rapid return of -it to the air and loss in drainage water's 

 appears to call for other agencies than those named. 



FIG. 27. Showing oats growing under conditions identical with those of 

 Fig. 26, except that the several pots received Chile saltpetre, 1, 2 

 and 3 grams respectively, thus enforcing the immense importance to 

 such plants of nitric nitrogen. After P. Wagner. 



4. Winogradsky lias shown that there is -a form of bacil- 

 lus in the soil which, when supplied with sugar and iso- 

 lated from the influence of oxygen, is capable of thriving 

 and fixing free nitrogen from the air, and this discovery 

 may lead to a knowledge of still a fourth mode of increas- 

 ing the world's supply of nitrogen. 



