Bacteria 33 



(B) Withflagella. 



1. Planococcus. Division in two directions of space, like micro- 



coccus. 



2. Planosarcina. Division in three directions, like sarcina. 



II. Family BACTERIACE^E. Cells more or less elongate, cylindric, and 

 straight. They never form spiral windings. Division in one 

 direction of space only, transverse to the long axis of the cell. 



(A) Without flagella. 



1. Bacterium. Occasional endospores. 



(B) Withflagella. 



2. Bacillus. Flagella arising from any part of the surface. 



Endospore-formation common. 



3. Pseudomonas. Flagella attached only at the ends of the cell. 



Endospores very rare. 



III. Family SPIRILLACE^E. Cells twisted spirally like a corkscrew, or 

 representing sections of the spiral. Division only transverse 

 to the long diameter. 



1. Spirosoma. Rigid; without flagella. 



2. Microspira. Rigid; having one, two, or three undulating 



flagella at the ends. 



3. Spirillum. Rigid; having from five to twenty curved or un- 



dulating flagella at the ends. 



4. SpirochfBta* Serpentine and flexible. Flagella not observed ; 



probably swim by means of an undulating membrane. 



B. SUB-ORDER: Trichobacteria (Higher Bacteria). 



IV. Family MYCOBACTERIACE^S. Cells forming long or short cylindric 

 filaments, often clavate-cuneate or irregular in form, and at 

 times showing true or false branchings. No endospores, but 

 formation of gonidia-like bodies due to segmentation of the cells. 

 No flagella. Division at right angles to the axis of rod in fila- 

 ment. Filaments not surrounded by a sheath as in Chlamydo- 

 bacteriaceae. 



1. Mycobacterivm. Cells in their ordinary form, short cylindric 



rods often bent and irregularly cuneate. At times Y- 

 shaped forms or longer filaments with true branchings 

 may produce short coccoid elements, perhaps gonidia. 

 (This genus includes the Corynebacterium of Lehmann- 

 Neumann.) No flagella. 



2. Actinomyces. Cells in their ordinary form as long branched 



filaments; growth coherent, dry or crumpled. Produce 

 gonidia-like bodies. Cultures generally have a moldy 

 appearance, due to the development of aerial hyphae. No 

 flagella. 



V. Family CHLAMYDOBACTERIACE^. Forms that vary in different 

 stages of their development, but all characterized by a sur- 

 rounding sheath about both branched and unbranched threads. 

 Division transverse to the length of the filaments, 

 i. Cladothrix. Characterized by pseudo-dichotomous branch- 

 ings. Division only transverse. Multiplication by the 

 separation of whole branches. Transplantation by means 

 of polar flagellated swarm-spores. 



* The spirochaeta and some closely related forms are now thought to 

 be more properly classified among the protozoa than among the bac- 

 teria. They will, therefore, appear again in the tabulation of the 

 protozoan organisms. 



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