PLANT ORGANS AND ORGANISMS 



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bacteria are found to exhibit variously shaped involution forms called 

 bacterioids. They remain within the cells of the medio-cortex region 

 gradually swelling up into zooglosa masses, until finally their bodies 

 break down into soluble nitrogenous substances which are partly 

 absorbed and assimilated and partly stored as reserve nitrogenous 

 food for the green leguminous plant. 



FIG. 65. Root system of a legume showing tubercles. (Marshall.) 



In the modern rotation of crops, plant growers plough under the 

 leguminous crops or their nodule-producing roots which decay and 

 enrich the soil with ample nitrogenous material to supply the next 

 season's crop of nitrogen-consuming plants. 



The writer has found tubercles on Myrica cerifera, Myrica Car- 

 oliniensis and Myrica Macfarlanei seedling primary roots of 5 to 6 

 months' growth, and from thence onward on the secondary roots 

 inserted on the hypocotyl axis, on nearly all the adventitious roots of 

 subterranean branches and on the subterranean branches of Myrica 



