The investigations by Truffaut and Bezssonoff (1925) make it seem probable that Clostridium pastorianum, which fixes atmospheric nitrogen abundantly in soil free from nitrogen and carbon, is able to draw its food from the root secretions of the higher plants (these experiments refer to Zea mais). (Braun-Blanquet 1932:235)
BRAUN-BLANQUET, Josias. 1932. Plant sociology: the study of plant communities. (Trans.: George D. Fuller; Henry S. Conard) New York: McGraw-Hill Book Company.