2O4 AGRICULTURAL BACTERIOLOGY. 



ment. The milk, when drawn, tastes as usual, and the bitterness 

 appears after standing for a few hours, increases in intensity, 

 and is at its maximum somewhat later. In these instances the 

 bitterness is produced by certain bacteria which grow in the 

 milk. As in other infections there are quite a number of spe- 

 cies known to produce a bitter taste in milk, although probably 

 only a small number are of practical importance. Many of the 

 peptonizing bacteria produce a bitter taste in milk after many 

 days, but they are manifestly not the cause of the common 

 trouble in the dairy. A few species have been described which 

 rapidly produce a very bitter taste, ruining the 

 flavor of the milk in a few hours. One of these 

 is a micrococcus (Fig. 27), and another is a ba- 

 cillus described by Weigmann. 



The source of these bitter milk bacteria in the 

 dairy has not been made out in many cases. In 

 one carefully investigated instance it has been 

 traced to the bacteria in the milk ducts of the 



A micrococcus , . , 11- r , i -,.1 



of bitter milk. cow a single cow in a herd being infested with 

 the organism sufficiently to contaminate the milk 

 of the whole herd. The entire isolation of her milk preserved 

 the rest of the milk from the bitter taste. A disinfection of 

 this cow's teats remedied the trouble. In another case the 

 bitter bacterium was believed to come from some turnips 

 which were fed to the cattle. Little as yet is really known 

 upon the matter. 



Blue Milk. A fermentation of milk which causes it to de- 

 velop a decided color is a very rare occurrence in practical 

 dairying. Although many bacteria are known which can pro- 

 duce such colors, they commonly act so slowly that the milk 

 is usually consumed before they have an opportunity to pro- 

 duce any noticeable effect. Occasionally, however, certain 

 colored milks are found even in ordinary dairying. 



The dairy infection longest known to be produced by bac- 



