Jan. 3) 1921 Nodule Bacteria of Leguminous Plants 545 



interesting r61e. As this same species undoubtedly takes part in 

 many processes occurring in soil and in water, it was thought useful to 

 give another more detailed description of it, especially because, despite 

 its ubiquity, B. radiobacter is much too little known. In addition to 

 the rather short description given by Beijerinck, only the more complete 

 one published by the senior author in 1905 exists thus far. On account 

 of its great similarity to B. radicicola, B. radiobacter should be very well 

 known to all bacteriologists working with the nodule bacteria in order 

 to avoid mistakes which may otherwise not be discovered until only 

 negative results are obtained in the inoculation tests. 



Concerning the flagellation of the nodule bacteria three statements 

 have been published more recently which also will have to be discussed 

 presently. According to J. K. Wilson (18) the soybean bacteria are 

 peritrichous ; Barthel (2) declared lupine and alfalfa bacteria to be 

 lophotrichous; Fred and Davenport (7) found the alfalfa organism 

 peritrichous, but they found the lupine bacteria characterized by having 

 one, rarely two, flagella. 



EXPERIMENTAL RESULTS 



The following strains of nodule bacteria were studied after having 

 been tested with positive results in regard to their ability to produce 

 nodules on the host plants from which they were isolated. 



1. Cowpea. 6. Red clover. 



2. Peanut. 7. Sweet clover. 



3. Japan clover. 8. Vetch. 



4. Beggar weed. 9. Strophostyles. 



5. Soybean. 



There were also included in our investigations two strains isolated 

 from: 



10. Black locust. 11. Lupine. 



No positive inoculation test could be made on black locust. The 

 lupine culture was kindly furnished by Dr. E. B. Fred, of the University 

 of Wisconsin, who had tried it with positive results on this plant. Our 

 tests were equally successful. 



Two noninfectious "fast growing" cultures isolated from legume 

 nodules and identified as Bacillus radiobacter were studied in comparison 

 with six Radiobacter strains which originated from soil and which were 

 kept in the senior author's collection since the years given in parentheses. 



12. Fast grower from cowpea. 16. Bacillus radiobacter from soil (1908). 



13. Fast grower from soybean. 17. Same (1908). 



14. Bacillus radiobacter from soil (1904). 18. Same (1908). 



15. Same (1907). 19. Same (1916). 



No. 14 is the strain which in 1904 had been acknowledged by Prof. 

 Beijerinck as being identical with his Bacillus radiobacter and which was. 

 used by the senior author for the original description published in 1905 



{12). 



