228 BACTERIA, YEASTS, AND MOLDS 



but cows probably do not have diphtheria, typhoid, or 

 scarlet fever. Danger from these diseases lies in the pos- 

 sibility that between the time of milking and the time 

 when it reaches the consumer the milk may have been con- 

 taminated with the bacteria which produce these troubles, 

 and that these bacteria, growing in the milk, may render 

 it a source of hidden danger. 



The relation of milk bacteria to the production of 

 summer complaint and similar diseases is not so well 

 understood. The only points that we need notice are : 

 (i) Such troubles are doubtless due to the bacteria present 

 in the milk. (2) They are consequently much more likely 

 to be associated with milk in summer than in winter, since 

 bacteria grow much faster in warm than in cold weather. 

 (3) Fresh milk which has been kept cool is less liable to 

 produce such troubles than older milk which has been 

 kept warm, partly, no doubt, because the latter contains 

 more bacteria than the former. Practically, then, the 

 housewife should remember that old milk that has been 

 kept warm is a source of danger, and that occasionally 

 even fresh milk may be the cause of the diseases above 

 mentioned unless some precautions can be adopted. 



How can precautions be taken in the household against 

 these possible dangers? i. We notice again that the milk 

 that costs the most is the best and most reliable, while 

 the cheapest milk is not only the poorest food but also 

 the most dangerous. 2. Where it is possible to obtain 

 information in regard to the character of the source of 

 milk, the danger of contracting disease may be lessened. 

 For in a small community knowledge concerning the man 

 who delivers the milk should enable one to get some idea 



