GENERAL MORPHOLOGY AND PHYSIOLOGY 43 



The type species is Mycobacterium tuberculosis (Koch) Lehmann and 

 Neumann. 



4. Cory neb acterium, Lehmann and Neumann, 1896. Synonyms: 

 Corynemonas Jensen 1909; Corynethrix Bingert 1901. 



Slender, often slightly curved, rods with tendency to club formation, 

 branching cells occasionally seen in old cultures. Barred irregular stain- 

 ing. Not acid-fast. Gram-positive. Non-motile. Aerobic. No en- 

 dospores. Some pathogenic species produce a powerful exotoxin. 

 Characteristic snapping motion is exhibited when cells divide. 



The type species is Corynebacterium diphtheria (Loeffler) Lehmann and 

 Neumann. 



5. Fusiformis, Hoelling, 1910. Synonym: Mantegazzaea Vuillemin 

 1913, not Mantegazzaea Trevisan 1879. 



Obligate parasites. Cells usually elongate and fusiform, staining 

 somewhat irregularly. Filaments sometimes formed; non-branching. 

 Non-motile. No spores. Growth in laboratory media feeble. 



The type species ( ?) is Fusiformis termitidis Hoelling. 



6. Leptotrichia. Trevisan, 1879 emended. Synonyms: Leptothrix 

 Robin 1847, n t Leptothrix Kuetzing 1843; Rasmussenia Trevisan 1889, 



Thick, long straight or curved threads,' frequently clubbed at one end 

 and tapering to the other. Gram-positive when young. Threads 

 fragment into short, thick rods. Anaerobic or facultative. Non-motile. 

 Filaments sometimes granular; non-branching. No aerial hyphae or 

 conidia. Parasites or facultative parasites. 



The type species is Leptotrichia buccalis (Robin) Trevisan. 



III. Family PSEUDOMONADACE.E. Short rods, usually motile. Flag- 

 ella single, polar. Gram-negative. Not obligate aerobes. Many species- 

 active ammonifiers. Many species produce water-soluble pigments or 

 green fluorescence; yellow pigment common. Some species are photo- 

 genic. Soil and water bacteria, with many plant parasites. 



i. Pseudomonas. Migula, 1894. Synonyms: Bactrillum Fischer 1895; 

 Arthrobactrillum Fischer 1895; Eupseudomonas Migula 1895; Bactrinius 

 Kendall 1902; Bactrillius Kendall 1902; Bacterium Ehrenberg emended 

 E. F. Smith 1905; Denitro mo nas Jensen 1909; Liquidomonas Jensen 1909. 

 ' Rod-shaped, short, usually motile by means of polar flagella or rarely 

 non-motile. Aerobic and facultative. Frequently gelatin liquefiers and 

 active ammonifiers. No endospores. Gram stain variable, though usu- 

 ally negative. Fermentation of carbohydrates as a rule not active. Fre- 

 quently producing a water-soluble pigment which diffuses through the 

 medium as green, blue, purple, brown, etc. In some cases a non-diffusible 

 yellow pigment is formed. Many yellow species are plant parasites. 



IV. Family SPIRILLACE^E Migula, 1894. Cells elongate, more or 



