SOILS. 



(tilth) of the surface soil so conducive to the welfare of cul- 

 ture plants, designated by German agriculturists as " Boden- 



gare." Whether or not this con- 

 dition is directly due to bacterial 

 processes, as is thought by Stut- 

 zer (Landw. Presse, 1904, No. 

 1 1 ) it is assuredly a highly im- 

 portant point to be gained, and 

 is essentially connected with the 

 presence of humus in adequate 

 amounts, which is also a favor- 

 ing condition of abundant bac- 

 terial life. It seems that the 

 FIG. ,8. -Bacillus subtiiis. (Woiiny, after preference given to the shallow 



Brefeld. . . r ,. 



putting-m, or even surface appli- 

 cation of stable manure, existing 

 in Europe, is largely based upon 

 the marked effect upon the loose- 

 ness of the surface soil, generally 

 credited to the physical effect of 

 the manure substance itself, but 

 apparently largely due to the in- 

 tensity of bacterial action thus 

 brought about. 



ROOT-BACTERIA OR RHIZOBIA 

 OF LEGUMES. Among the most 

 important bacteria, agricultur- 

 ally, is that which enables plants 

 of the leguminous order (peas, 

 beans, vetches, clovers, lupins, 

 etc.), to obtain their supply of 

 nitrogen from the air independ- 

 ently of those contained in the 

 soil. The source of nitrogen 

 to plants was long a disputed 

 question ; it was at first supposed 

 ( by cle Saussure) that it was ob- 

 tained directly from the soil by 

 the absorption of humus ; but this was disproved, and Liebig 

 then contended that it was derived directly from the atmos- 



FlG. 19. Bacteria producing ammoniacal 

 fermentation : A , C. mycoides : B, B. stut- 

 zeri. (From Conn, Agr. Bacteriology.) 



FIG. 20. Bacillus 



Migula.) 



magaterium. ( From 



