TYPES OF BACTERIA FOUND IN MILK 



53 



FIG 28 B. CYANOGENES 



until the whole finally becomes a deep blue color. The cause 

 of the phenomenon was studied 

 in 1840 and found to be a bac- 

 terium, to which the name 

 Bacillus cyanogenes was 

 given. 1 This bacterium has 

 been found many times since, 

 and is one of the well known 

 dairy organisms. (Fig. 28.) 

 It is not very common, how- 

 ever, and dairy infections due 

 to blue milk are extremely 

 rare. The organism has been 

 found in Europe and Amer- 

 ica, also, but dairy infection of blue milk has seldom been 

 reported from American dairies. It is very easy, however, to 

 produce blue milk by inoculating with the bacteria in question, 

 but it does not seem to have been of common occurrence enough 

 to have caused much trouble in this country. 



Red Milk. A red color in milk is not an uncommon phe- 

 nomenon. Often it is because the milk is bloody, through 

 some wound in the udder. Sometimes cows give red milk after 

 eating madder, or some other plants. In all these cases the 

 trouble shows itself at the time of milking. But, in addition to 

 such causes, red milk is sometimes due to bacteria, although as 

 a dairy phenomenon, this is of very rare occurrence. When 

 it does occur, the milk is generally red only on the surface. 

 Several bacteria are known to make milk red, among which are : 

 B. prodigiosns, Bad. erythrogenes and B. lacto nibifaciens and 

 others. They are fairly common in milk, but rarely do they 

 cause any trouble. 2 



tpuchs. Mag. f. d. ges. Thierh., 1841. 



- Baginsky. Cent. f. Bact., v., p. 448, 1889. 



Gruber. Cent. f. Bact., II., viii., p. 457, 1902. 



Gratz. Milch. Zent., i., p. 9, 1905. 



Menge. Cent. f. Bact., I., vi., p. 596, 1889. 



