46 THEORIES ON THE ABSORPTION OF NITROGEN 



Beijerinck, Gerlach, and Vogel had no success at all 

 with the sowing of Asotobacters, although Professor Hall, 

 of Rothamsted, made some encouraging observations. 

 The only result obtained by Koch was with Asotobacter 

 chroococcum, which fixed nitrogen in presence of repeated 

 doses of sugar in small quantities. 



From all these experiments we may apparently draw the 

 conclusion that all these bacteria are able to exist in the 

 soil, but that it is the conditions for reproduction which are 

 unfavourable. All farming operations, such as draining, 

 ploughing, loosening the soil in various ways, or any other 

 methods which tend to favour the development of these 

 micro-organisms, will increase soil fertility considerably 

 more than any possible kinds of artificial inoculations. The 

 method of treatment by actual soil appears to be the only 

 one which has a marked effect, but it will always be difficult 

 in practice if the two places concerned are widely separated. 



In Mauritius, where the majority of Leguminosae do well, 

 there is especial need to use them as much as possible for 

 ploughing in, and occasionally for seed. 



