Desiccated Nodules as a Source of the Root‐Nodule Organism

Nodule s o f a larg e numbe r o f legume s hav e bee n employe d i n thi s study . The y may b e collecte d wheneve r foun d an d hel d fo r fu tur e work . Th e nodule s ar e washe d fre e o f soi l an d allowe d t o dr y spontaneously , the n stored . Suc h nodule s hav e bee n a sourc e o f th e root-nodul e bacteri a fo r a n extende d perio d o f time . A t leas t fo r one yea r th e organis m may b e easil y isolated . Th e desiccate d nod ul e i s place d i n water . I t wil l resum e approximatel y it s origina l size . Thi s may tak e thirt y minute s fo r nodule s o f certai n legume s or severa l hour s fo r others . Afte r thi s soaking-u p proces s th e nodul e may b e handle d a s a fres h nodule . The y hav e bee n desiccat ed a s fa r awa y a s Chin a an d sen t t o ou r laboratory , wher e th e root nodul e bacteri a wa s isolate d b y followin g th e abov e procedure . Also , nodule s wer e collecte d i n th e summer tim e an d employe d i n clas s wor k durin g th e followin g spring . However , becaus e o f th e smallnes s o f th e drie d specimens , student s destro y to o muc h desiccate d materia l t o mak e thi s metho d ver y servicabl e fo r laborator y exercises .