154 BACTERIA IN MILK. 



way, it becomes viscid, and finally it may be so slimy that it can 

 be drawn out into long threads. At the same time it has a sweetish 

 taste. Such milk is practically worthless. It cannot be used for 

 butter-making, for the cream will not separate. It will not be used 

 for drinking 01 cooking purposes, although there seems to be no 

 reason for believing that it is not perfectly wholesome. In some 

 countries, indeed, such slimy milk is a favorite beverage; but in this 

 ^ country most people, not wishing to drink slime, will 



throw it away. Sometimes such an infection proves 

 very troublesome. It may spread through a whole 

 farming district, affecting many dairies and continuing 

 **,* for a long time. Although not always easy to follow, 

 1 1* such infections may generally be traced to some com- 

 Fic.36. B. mon source of distribution. For example, a central 



lactisviscosus; . . IT' -n <- 



the common creamery, receiving such slimy milk from some patron, 



Distribute tne trou t>le over the whole patronizing 

 district by returning to the farmers the milk vessels 

 not properly sterilized. 



The cause of this sliminess is the growth of bacteria. Several 

 different kinds of bacteria have been discovered with this property. 

 The best known of them, and probably the most common, is one that 

 has been named B. lactis viscosus (Fig. 36). This has been found 

 to be the cause of the trouble in Europe, and a similar if not the 

 identical organism has been found in America. It appears to be 

 a very vigorous organism, and, when once present, will grow so 

 rapidly as to make the milk slimy in spite of the action of the ordinary 

 acid-forming bacteria that may be present. 



To understand the sources from which this troublesome organism 

 is derived may be a matter of great importance to a dairyman. 

 Three sources have thus far been detected: i. Sometimes it may 

 come from water used in washing the milk cans or, more likely, 

 from the water in which the cans have been standing to cool the 

 milk. 2. It may come from the udder of the cow; perhaps a single 

 cow in a herd being thus infected and her milk contaminating that 

 of the whole dairy. 3. Slimy milk bacteria have been found in the 

 dust of the air in dairies. If, therefore, a dairy is troubled with 



