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. -Hadiius subtiiis. ( Woiiny, after preference given to the shallow 



Brefeld. . ... 



putting-m, or even surlace 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- 

 tnisitv of bacterial action thus 

 brought about. 



ROOT-I;.UTKKIA OK RIIIZOBIA 



or i.KcrMKs. Among the most 

 important bacteria, agricultur- 

 ally, is that which enables plants 



of the leguminous order- (peris. 

 b<.'an>. 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 wis at first supposed 

 ( by de Sruissure) 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- 



FIG. iq. Bacteria producing ammoniacal 

 fermentation: A, C. my* c/</'.v : />'. />'. sttit- 

 zeri. (From Conn, Agr. I'.arU-riology.) 



FIG. 20. Bacillus 



MiguLi ' 



magaterium. (From 



