UACTERIA IN MILK. 2OI 



through a whole farming district, affecting many dairies and 

 continuing for a long time. Although not always easy to under- 

 stand, when such infections have been studied the trouble may 

 generally be traced to some common source of distribution. For 

 example, a central creamery receiving such milk from some 

 patron, may distribute it over the whole patronizing district by 

 returning the milk vessels not properly sterilized by live steam. 



Wherever such slimy milk appears it may always be traced 

 to the action of bacteria. As in the case of other fermenta- 

 tions it is not a single species of bacterium which has this 

 power of producing slimy milk, but rather a somewhat large 

 class of organisms. More than a score of bacteria have been 

 described as possessing the power of producing a slime in 

 greater or less amount. Moreover it appears, according to 

 recent work, that some of the common dairy bacteria (B. 

 acrogcnes lactis) are capable, under some conditions, of produc- 

 ing a sliminess. But of this large number of species prob- 

 ably only a few are concerned in the actual dairy infections, 

 since most of them produce the effect very slowly and are not 

 vigorous enough to render the milk slimy when 

 they have to contend with ordinary lactic bacteria. 



Slimy milk appears to be produced in dairies by % 



one or two widely distributed bacteria. The most 



common one seems to be a short rod (Fig. 26), N/ 

 which does not produce spores and is therefore ^o S\ 9 j 

 readily killed by heat. This bacterium has been ***i* 



found a common cause of this trouble in the 

 United States. Further, it so closely resembles 



vtscosus ; the 



a slimy milk bacterium described in Europe by common cause 



., ... 111 i of slimy milk. 



Adametz that it is probably to be regarded as (Ward.} 

 the same, and is consequently known by the name 

 given by Adametz, B. lactis viscosus. It appears to be a very 

 vigorous organism and, when once present in the milk, will 

 grow so rapidly as to make it slimy in spite of the action of 

 the ordinary lactic bacteria which are present. 



