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enters into the circulation in the root to which the nodule is 

 attached, and thence is carried in the sap to build up all parts 

 of the leguminous plant. 



Inoculation or Soil or Seed, 



Every plant suitable for the growth of root tubercles 

 ought to have an abundant supply of them. The writer has 

 never found a cowpea plant of suitable age and grown under 

 normal conditions which was free from tubercles. 



Yet some plants that can form tubercles are sometimes 

 found to have none. The writer has examined hundreds of 

 individual clover and vetch plants on which there were no 

 tubercles. For such plants the farmer has no use. They are 

 no more doing the work they should do than is a barren stalk 

 of corn. 



Why do leguminbus plants under some conditions fail to 

 form tubercles ? It is because the proper germ (" seed," so to 

 speak) is absent from the particular soil in which legumes 

 grow without root nodules. In order for tubercles to form 

 on a given leguminous plants a specific germ must be present. 

 For clover this must be a germ or bacterium of that particular 

 strain or stock which is accustomed to grow in clover 

 tubercles ; for vetch it should be the kind of germ which is 

 accustomed to grow in vetch tubercles ; and so for other 

 plants. 



Inoculation consists in placing a supply of these germs in 

 such position that the young roots of the leguminous plants 

 will come in contact with them. We may inoculate either the 

 soil or the seed. 



Individual tubercles are short-lived, and when one decays 

 it distributes in the surrounding soil a great multitude of 

 germs or root- tubercle bacteria which serve the purpose of 

 seed for the next crop of tubercles. Thus in an old clover 

 field are myriads of clover germs, in an old vetch field 

 multitudes of vetch germs, and so for other legumes. Hence 

 when clover follows clover or when it is sown in a locality 

 where the growth of clover is general and clover germs 

 generally distributed, artificial inoculation is unnecessary. 



