BACTERIA IN MILK. IQI 



lead one to expect that it is these bacteria chiefly which get 

 into the milk during the milking. This, however, does not 

 appear to be the case, for, when fresh milk is studied, it is 

 found, in many cases, that the bacteria of other types far out- 

 number the lactic organisms. Sometimes, indeed, the lactic 

 bacteria are so few in fresh milk or cream that they cannot be 

 found by ordinary methods of analysis, the other bacteria out- 

 numbering them a hundred fold. Nevertheless, when this 

 same sample of milk is examined a few hours later, it will be 

 found that the lactic bacteria have become more numerous 

 than the other types and, if the milk be examined later still, 

 when it has become distinctly acid, it will be seen that the 

 lactic bacteria have increased so prodigiously that they consti- 

 tute nearly the whole. The meaning of this fact is evident. 

 There is doubtless a great struggle among the bacteria in 

 the milk and, whereas many different kinds of bacteria com- 

 monly find their way into the milk at the time of milking, 

 the lactic bacteria find the conditions very much more favor- 

 able to their growth than do the other types. They increase 

 with a much greater rapidity than the others and finally actu- 

 ally crowd the other types of bacteria out of existence. In a 

 well-soured cream all bacteria except the lactic bacteria may 

 have disappeared, even though others were at first in 

 abundance. 



From these facts it will be seen how absolutely hopeless it 

 is for the dairyman to try to avoid the presence of lactic bac- 

 teria. Some of them will be sure to find their way into the 

 milk, and if so, they will find such favorable conditions for 

 growth that they will soon become very numerous. Some- 

 thing may be done toward procuring milk with a high keep- 

 ing quality, by trying to reduce the number of bacteria 

 which get into the milk ; but the greatest dependence must 

 be placed upon the use of cold as a method to prevent their 

 growth. 



