68 AGRICULTURE 



work up into organic compounds, this free 

 nitrogen, and afterwards hand it on to the 

 plants on which the colonies have established 

 themselves. This association of two organ- 

 isms for the mutual benefit of both is not 

 \mcommon both amongst plants and animals. 

 In the case we are considering the legu- 

 minous plant offers, as it were, house-room 

 to the bacteria, which, in return for the 

 .accommodation thus provided, convert 

 the free nitrogen into such a form that it 

 can be appropriated by the higher plant. 



Without these colonies of bacteria the 

 xLeguminosse are practically as helpless with 

 tregard to nitrogen as any . other plants. 

 It has been asserted that it is a matter of 

 chance whether any particular leguminous 

 plant shall come into contact in the soil 

 with its appropriate organism, and it has 

 Ibeen suggested that fields intended for the 

 rgrowth of a leguminous crop should be 

 " inoculated " with a culture of the organ- 

 ism which can best enter into association 

 -with the particular crop that it is intended 

 to grow. Various so-called cultures have 

 from time to time, during the past ten to 

 fifteen years, been put upon the market, and 

 farmers and gardeners have been led to 

 expect great results from their use. But in 



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