THE CLASSIFICATION OF BACTERIA 329 



CLASS VI. NITROMONAS GROUP OF WINOGRADSKY 

 Do not grow in nutrient gelatin or other organic media. 



44. Ps. Europaea (Winogradsky) Migula 



Nitromonas Europcea Winogradsky : Archiv Sci. biol. St. Petersbourg I, 1892, Nos. 1-2. 

 Ps. Europcea Migula: Die Natiirlichen Pflanzenfam., 1892, 29. 



Morphology. Bacilli 0.9-1.0:1.1-1.8 //,; occur singly, rarely in chains 

 of 3-4 elements, coccoid forms short rods. A single polar flagellum 

 2-3 times the length of a rod, or rarely one at either end. Grow readily 

 in a fluid medium composed of tap water, i litre ; ammonium sulphate, 

 i gramme ; potassium phosphate, I gramme ; and basic carbonate of mag- 

 nesia, 10 grammes. The organisms united in zoogloea^^sses adherent to 

 the particles of magnesium carbonate in the bottom of the flask. On 

 Kiihne's gelatinous silica medium (Zeitsch. f. Biol., XXVII, 1890, Heft i ; 

 Migula System der Bakterien, I, 1897, 263). Compact, sharply defined 

 colonies of a brownish color; after 10-14 days the colonies spread some- 

 what and are bright uncolored masses with differently formed outgrowths. 

 Ammonium salts converted into nitrites. 



Habitat. Isolated from soils from Europe, Africa, and Japan. 



45. Ps. Javanensis (Winogradsky) Migula 



Nitromonas Javanensis Winogradsky : I.e. 

 Ps. Javanensis Migula : I.e. 



Morphology. Bacilli small, ovoid, 0.2 : 0.5 /*. A polar flagellum 20 times as 

 long as the rod. In fluid inorganic media as in (44) ; minute flocculi or 

 scales adherent to the walls of the flask ; no turbidity. On KUhne's 

 silica medium the colonies are round elliptical. Nitrites are converted 

 into nitrates. 



Habitat. Isolated from Quito soil. 



CLASS VII. CELLS WITH REDDISH PLASMA AND WITH SULPHUR 

 GRANULES. CHROMATIUM PERTY. 



46. Ps. Okenii (Ehrenberg) Migula 



Monas Okenii Ehrenberg : Die Infusionstierchen, 1838. 

 Ps. Okenii Migula : Die Natiirlichen Pflanzenfam., 1892. 



Bacilli short, ovoid forms, 0.5 : 8.0-15.0 /x, with 1-3 polar flagella. 



47. Ps. rosea Migula : I.e. 



Bacilli long, cylindrical, 2.0: 8.0-1.2 /a, with 1-3 polar flagella. 

 It is doubtful whether the two last species should be included in this genus. 



