564 MANUAL OF DETERMIXATIVE BACTERIOLOGY 



TKIBE III. BACTEROIDEAE TRIE. NOV. 



Motile or non-motile rods without endospores. May or may not require enriched 

 culture media. Obligate anaerobes. Gram -negative. 



Key to the genera of tribe Bacteroideae. 



I. Cells with rounded ends. 



Genus I. Bacteroides, p. 564. 

 II. Cells with pointed ends. 



Genus II. Fusohacterium, p. 581. 



Genus I . Bacteroides Castellani and Chalmers.* 



(Man. Trop. Med., 3rd ed., 1919, 959.) 



Characters as for the tribe. From Greek, like a rod. 



The type species is Bacteroides fragilis (Veillon and Zuber) Castellani and Chalmers. 



Note : The descriptions have been taken largely from Weinberg et al. (Les Microbes 

 Anaerobies, Paris, 1937, 658); Prevot (Ann. Inst. Past., 60, 1938, 285); Hauduroy, 

 Ehringer, Urbain, Guillot and Magrou (Diet. Bact. Path., Paris, 1937, 51); and Eg- 

 gerth and Gagnon (Jour. Bact., 25, 1933, 389). Because cultures of many of these 

 organisms have not been subjected to critical study with identical tests and media, 

 it is difficult to know how many should be considered as distinct species, and the 

 present arrangement must be considered as tentative. The key, of necessity, has 

 been drawn up from recorded characters which appeared useful for. the purpose and 

 these on further study may prove to be inadequate. 



Key to the species of genus Bacteroides. 



I. Not requiring enriched media. 

 A. Gas formed from proteins. 



1. Hydrogen sulfide not produced, 

 a. Non-motile. 



aa. Motile. 



2. Hydrogen sulfide produced, 

 a. Indole not formed. 



b. Very pleomorphic. 



1. Bacteroides fragilis. 



2. Bacteroides serpens. 



3. Bacteroides funduliformis. 



bb. Not markedly pleomorphic. 



4. Bacteroides siccus. 

 aa. Indole formed. 



b. Gelatin liquefied. 



5. Bacteroides coagulans. 



* Completely revised by Dr. T. E.Roy, Bacteriologist to the Hospital for Sick Chil- 

 dren, Toronto, Ontario, Canada and Dr. C. D. Kelly, Assistant Professor of Bacteriol- 

 ogy, McGill University, Montreal, P. Q., Canada, December, 1938; rearranged, Decem- 

 ber, 1945. 



