BACTERIA, NOT CLASSIFIED. .727 



in the form of a thin layer having numerous vacuoles ; sometimes a thick 

 and shining 1 layer is developed which has a pale sulphur-yellow color or is 

 of a dull-brown mixed with yellow. In bouillon a cloudy opacity is first 

 developed ; later a flocculent deposit is seen and the liquid above is limpid ; 

 it is slightly viscid. In sterilized milk the viscosity produced is so great 

 that, in old cultures, threads may be drawn out which are several metres in 

 length. Non-sterilized milk becomes viscous at the end of five hours ; later 

 it becomes acid, and at the end of several days the casein is coagulated and 

 is seen as a granular precipitate, above which is a limpid and viscous serum ; 

 at this time the milk has acquired a disagreeable odor. 



472. BACTERIUM HESSii (Guillebeau). 



Obtained from the milk of a cow in the Alps, at an altitude of twelve 

 hundred metres. 



Morphology. Bacilli from 3 to 5 jn long and 1.2 fi thick (from potato cul- 

 tures) ; shorter, nearly spherical elements are also seen in considerable num- 

 bers, and occasionally long filaments ; the ends are round and stain more 

 deeply than the central portion. 



Biological Characters. An aerobic, liquefying, motile bacillus. Forms 

 spores. Grows in the usual culture media at the room temperature. In 

 nutrient gelatin containing serum from milk, colonies are developed upon 

 plates at the end of a few hours ; these at first have well-defined outlines, 

 but later are made up of interlacing filaments ; after liquefaction of the gela- 

 tin the colony floats upon the surface; liquefaction progresses rapidly and 

 the liquefied gelatin may be drawn out into threads. Upon potato a shin- 

 ing layer is developed of a dull-white color, which later acquires a brownish 

 tint. Bouillon without sugar is rapidly transformed into a viscous mass 

 having an alkaline reaction. In milk an acid reaction is produced and the 

 casein is precipitated at the end of two days. The viscosity produced in 

 milk is less than that produced by the species previously described, and dis- 

 appears at the end of two days in milk kept at a temperature of 35 C. In 

 old cultures in bouillon a disagreeable odor is developed, said to resemble 

 trimethylamin. 



473. BACILLUS DENITRIFICANS. 



Obtained by Giltay and Aberson from the soil and from the air. Resem- 

 bles Bacterium denitrificans of Gayou and Dupetit. 



Morphology. Bacilli, usually in pairs, 1.5 n to 3 ft long and 0.5 M broad. 



Biological Characters. Completely decomposes nitrates, producing ni- 

 trogen monoxide as well as pure nitrogen. The reducing action of the fer- 

 ment is favored by the presence of carbonate of lime in the culture medium. 

 Grows in ordinary nutrient gelatin. Also cultivated in the following me- 

 dium: Nitrate of potash two grammes, glucose two grammes, sulphate of 

 magnesia two grammes, citric acid five grammes, monophosphate of potash 

 two grammes, calcium chloride 0.2 gramme, two drops of a solution of per- 

 chloride of iron, and one litre of water. 



474. BACILLUS CYANO-FUSCUS. 



Obtained by Beyerinck from size and glue and Edam cheese. 



Morphology. Bacilli from 0.2 to 0.6 /J. long and one-half as thick. 



Biological Characters. An aerobic, chromogenic, liquefying, motile 

 bacillus. Grows in the usual culture media at the room temperature. 

 Spore formation not observed. When cultivated in a solution containing 

 one-half per cent of peptone the culture medium acquires at first a green 

 color, which later changes to blue, brown, and black; subsequently the color 

 is almost entirely lost. In nutrient gelatin containing one-half per cent of 

 peptone circular colonies are developed which are surrounded by a zone of 

 black pigment and in which crystals of lime are formed. 



