BACTERIA IN MILK. 2OQ 



hind and, by the time the lactic acid begins to appear, the 

 growth of other bacteria is commonly checked. The other 

 species thus ordinarily do not produce any considerable effect 

 on the milk. Sometimes, however, some of the other varie- 

 ties of bacteria may be especially numerous, or sometimes 

 other vigorously growing bacteria besides the lactic organisms 

 may get into the milk. If this occurs these unusual species 

 may develop to such an extent as to stop the growth of 

 the lactic bacteria and prevent the milk from souring. These 

 unusual bacteria then produce certain changes of their own in 

 the milk, resulting in the various types of abnormal milk fer- 

 mentations which are sometimes so troublesome in the dairy. 

 Such unusual fermentations are always due to unusual causes, 

 and by exercising a little care in the way of cleanliness, cleans- 

 ing the milk vessels, using pure water and allowing no cold 

 water of any kind to stand in the milk vessels, they may gener- 

 ally be avoided. If once in the dairy, they must be removed 

 by finding, if possible, their source, and then using simple 

 means of disinfection and thorough cleansing. Cleanliness 

 must be the dairyman's watchword. 



A few most important conclusions should be remembered 

 by every one who handles milk, either as producer or shipper. 



1. Practically all the difficulties experienced in the distri- 

 bution of milk are to be attributed to the great multiplication 

 of bacteria in the milk. 



2. The remedies for these universal troubles are first, cleanli- 

 ness, directed to the cow, the milk vessels and the milker ; and 

 second, the application of loiv temperatures as soon as possi- 

 ble after the milk is drawn. 



3. Even with the best of precautions the lactic bacteria are 

 sure to multiply in the milk and against them the only de- 

 fense is low temperature. 



4. Preservatives which are sometimes added to the milk, 

 boracic acid, salicylic acid, formalin, or the various commer- 



18 



