Bacillus Cyanogenus, Fuchs (1841). 



BACILLUS OF BLUE MILK. 



ORIGIN. It was obtained from blue milk. 



FORM. Small, rather narrow rods, with slig-htly 

 rounded ends, 2 to 3 times as long- as wide. It frequently 

 grows in pairs, very rarely in threads. 



MOTILITY. Very actively motile. Bunch of whips at 

 one end. 



SPORULATION. The small terminal spore-like bodies 

 observed by some are probably involution forms. True 

 spores have been observed to form on althea or quince jelly. 



ANILIN DYES. It stains easily. 



GROWTH. Rapid. 



Gelatin plates. The deep colonies are round with sharp, smooth 

 border, and yellowish granular contents. The surface colonies are 

 moist, elevated, convex masses, which are round, finely granular and 

 dark colored. At times the colonies may be thin, spreading" and with 

 an irregular border. 



Stab culture. Little or no growth in the lower part of the punc- 

 ture. It spreads over the surface as a thick, moist, dark-gray cover- 

 ing-. A dark steel-blue color diffuses downward into the gelatin. The 

 shade of color varies with the reaction of the medium. In neutral 

 or acid media it is quite blue, whereas in very alkaline media it is 

 dark, or even black. The culture when old becomes dark colored. 



Streak culture. On agar, it forms a dirty gray, thick, moist cover- 

 ing-, and the medium becomes dark colored. On potato, it likewise 

 forms a thick, raised, slimy growth, which rapidly spreads and be- 

 comes colored, On blood-serum, no color is formed. 



Milk. In sterilized milk it produces no acid or coagulation, but 

 the liquid becomes colored a slate-gray which with acids turns blue. 

 In unsterilized milk, that is in presence of lactic acid bacteria, the 

 color is sky-blue. The color is developed from casein, not from 

 lactose. In bouillon or milk containing 2 per cent, of glucose it forms a 

 splendid blue color and lactic acid. It does not convert lactose into 

 an acid. 



OXYGEN REQUIREMENTS. Aerobic. 



TEMPERATURE. It grows best at the ordinary tempera- 

 ture; to less extent in the incubator. The pigment is most 

 marked when growth occurs at low temperatures, 15-18. 



BEHAVIOR TO GELATIN. This is not liquefied. 



PATHOGENESIS. It has no effect on animals. 



The production of a blue color in milk is frequently observed, 

 and, as in the case of red milk, this is due to the development of 

 certain species of bacteria. 



230 



