86 THE TYPES OF MILK BACTERIA. 



have resisted the heat of sterilization; (3) a bitter taste in 

 cheese. 



These three phenomena are produced by microorganisms. 

 The bitter infection of fresh milk, in the one case studied, 

 .was found to be due to a micrococcus which developed 

 rapidly and , rendered the milk bitter and somewhat slimy. 

 Washing the cows' udders with two per cent, soda and the 

 milk duct with three per cent, boracic acid cured one such 

 trouble (80). The bitterness in sterilized milk may be pro- 

 duced by a considerable variety of bacteria, but is a phenom- 

 enon of comparatively little importance. The bitter taste in 

 cheese has been found to be due in one case to a bacterium, 

 which was isolated and experimented .with (79), and in 

 another case to the development of a species of yeast. This 

 phenomenon will be considered in a later chapter. 



The source of the bacteria which produce the bitter taste 

 in milk has been made out in one case, where it was traced 

 to bacteria present in connection with the milk ducts of a 

 cow. A single cow was found to be infested with a bac- 

 terium which produced a bitter taste and the trouble disap- 

 peared from the dairy as soon as this cow's milk was sepa- 

 rated from the general supply. The milk of this cow became 

 free from the trouble after her teats were disinfected. At 

 present little further is known in regard to the infection of 

 bitter milk. 



Soapy Milk. This is an infection which occurs rarely, 

 only one or two instances having been recorded (82). It is 

 characterized by a frothing of the milk, a soapy feeling, a 

 peculiar taste, and has been traced by Weigmann to the pres- 

 ence in the milk of a special bacterium. Its origin appeared 

 to be from the straw and hay of the stable, or from the pas- 

 tures. It is such a rare incident that it needs no further 

 reference. 



