106 THE CREAMERY PATRON'S HANDBOOK. 



Among such may be mentioned the formation of alcohol, due manliy to 

 yeasts, pigment fermentations such as blue, red or bloody, yellow and 

 green milks; but these do not occur frequently enough to merit a furthei 

 consideration in this connection. 



The fermentations so far referred to are the result of bacterial action. 

 They are not diseases in the strict sense of the word, but they affect mater- 

 ially the commercial value of milk. 



DISEASE BACTERIA IN MILK. 



Besides these bacterial defects or troubles, there are certain bovine 

 diseases of a contagious character in which the milk of the diseased ani- 



PlG. 10. Bacterial content of milk handled in ordinary way. Each spot represents a colony 

 growing on gelatine plate. Compare with Fig. 11 (opposite page) where same quantity of milk 

 is used in making culture. Over 15,000 bacteria per cc. in this milk. 



mal may be infected with bacteria dangerous to health. In some instances 

 the milk secretion is so changed by the disease, as in anthrax fever, that 

 its abnormal appearance in connection with the condition of the animal 

 would lead to its rejection. In other animal diseases, the milk may show 

 no physical peculiarity that would enable one to recognize its true state. 

 As for instance, in tuberculosis, the milk secretions remain apparently 

 unimpaired for a considerable period, and it is only where the disease be- 

 comes aggravated, especially in the mammary glands, that the appearance 

 of the milk is markedly changed. 



The majority of the bacteria that are capable of causing contagious dis- 

 eases gain access to milk after it is drawn. Persons convalescing from 

 fevers may infect the milk, or individuals who care for the sick may 



