HETEROTROPHIC BACTERIA REQUIRING COMBINED NITROGEN 143 



form of spores. The spores vegetate in the presence of a large amount 

 of organic matter and an excess of moisture. 4 



A detailed study of the spore-forming bacteria has been made by 

 various investigators 5-8 and recently by Ford 9 and associates, whose 

 work is used as a basis for the following classification. 



Classification of Spore-forming Bacteria 9 



Group I. Subtilis group 



Small, homogeneous, sluggishly motile organisms measuring 0.4 by 1.5 to 

 2.5ju. No threads on glucose agar. Central or excentric spores, oval, measuring 

 0.5 by 0.75 to 0.88;u, often retaining terminal tags of protoplasm. Growth on 

 solid media hard and penetrating, with tenacious scums on fluid media. 

 Bacillus subtilis Cohn 

 Bacillus subtilis-viscosus Chester 

 (Characterized by viscosity) 



Group II. Mesenlericus group 



Small, homogeneous, actively motile organisms measuring 0.5 by 2 to 4^. 

 They often produce long threads on glucose agar. The spores measure 0.5 by 

 1 to 1.12/i, oval and retaining terminal tags of protoplasm. The growth on 

 solid media is a soft pultaceous mass with tendency to wrinkle; on fluid media, 

 growth is in the form of a friable easily-broken scum. 

 Bacillus vulgatus (Flugge) Trevisan 



(Bacillus mesentericus vulgatus Flugge) 

 Bacillus mesentericus (Flugge) Migula 



(Bacillus mesentericus fuscus Flugge) 

 Bacillus aterrimus Lehmann & Neumann 



(Bacillus mesentericus niger Lunt) 

 Bacillus globigii Migula 



(Bacillus mesentericus ruber Globig) 



4 Winogradsky, 1924 (p. 542). 



6 Gottheil, O. Botanische Beschreibung einiger Bodenbakterien. Centrbl. 

 Bakt. II, 7: 430^35, 449^65, 481^97, 529-544, 582-591, 627-637, 680-691, 717-730. 

 1901. 



6 Neide, E. Botanische Beschreibung einiger sporenbildenden Bakterien. 

 Centrbl. Bkt. II, 12: 1-32, 161-176, 337-352, 539-554. 1904. 



7 Chester, F. D. Observations on an important group of soil bacteria. Organ- 

 isms related to Bacillus subtilis. Del. Agr. Exp. Sta., Rept. 15: 42-96. 1904. 

 A review of the Bacillus subtilis group of bacteria. Centrbl. Bakt. II, 13: 737- 

 752. 1904. 



8 Holzmiiller, K. Die Gruppe des Bacillus mycoides Flugge. Centrbl. Bakt. 

 II, 23: 304-354. 1909. 



9 Ford, W. W., Lawrence, J. S., Laubach, C. A., and Rice, J. L. Studies on 

 aerobic spore-bearing non-pathogenic bacteria. Jour. Bact. 1: 273-320, 493-534. 

 1916. 



