JOURNAL OF AGRICULTURAL RESEARCH 



DEPARTMENT OF AGRICULTURE 



Vol. VI Washington, D. C, July 31, 1916 No. 18 



LIFE CYCLES OF THE BACTERIA 



[preliminary communication] 



By F. Lohnis, Soil Biologist, and N. R. Smith, Scientific Assistant, Bureau of Plant 



Industry. 1 



INTRODUCTION 



Two years ago the senior author, together with J. Hanzawa (i4), 2 pub- 

 lished the results of some Azotobacter studies, showing for the first time 

 that the large Azotobacter cells are a special type of growth of a spore- 

 forming bacillus. We said (14, p. 2) : 



Es stent jetzt fest, dass in der Tat die grossen, sporenfreien Azotobacter-Zelien 

 Wuchsformen eines schlanken, Endosporen bildenden Bacillus sind. Bacillus Azo- 

 tobacter ist demnach die korrekte Bezeichnung fur diese Art. 3 



As we had to discontinue our investigations at that time, we pointed 

 out (14, p. 6) that further research in this direction would be very 

 desirable : 



Sicherlich wiirden weitere Forschungen in dieser Richtung noch manchen fur den 

 Systematiker wie fur den Physiologen gleich wichtigen Einblick erschliessen. 



In the meantime some new papers on Azotobacter have been pub- 

 lished. But they merely confirmed once more certain facts concerning 

 the normal growth and the rather general occurrence of Azotobacter in 

 soils. Only one author, Mulvania (15), reports the presence of heat- 

 resisting spores. In the other cases no spores were observed. However, 

 they undoubtedly would have been found by a more thorough search. 

 One of these authors readily admitted this fact in a letter, saying that 

 his statement had been made "on the basis of the ordinary examination 

 always made by soil bacteriologists." 



1 The photomicrographs, as well as the final drawing cf the text figure accompanying this paper, have 

 been made by Mr. F. L. Goll, of the Bureau of Plant Industry. Grateful acknowledgment is due him for 

 his very careful work. 



2 Reference is made by n-umber to "Literature cited," p. 701-702. 



3 In accordance with the usage of K. B. Lehmann and most of the other European bacteriologists, we apply 

 the name "Bacillus" to the spore-forming rods. As Bacillus azotobacter, like most, probably all, spore- 

 forming rods, has, at least temporarily, peritrichous flagella, its name would also be valid if Migula's system 

 should be preferred. However, we fully agree with Lehmann, that this system is especially unsatisfactory. 



Journal of Agricultural Research, Vol. VI, No. 18 



Dept. of Agriculture, Washington, D. C July 31, 1916 



ez -G— 89 



(675) 



