70 THE MILK QUESTION 



a public health standpoint as the kind of bacteria and the 

 nature of the bacterial products. With cleanliness and a 

 liberal use of ice, the large number of bacteria can be kept 

 down and this affords a certain amount of protection 

 against the dangerous varieties and the development of 

 their toxic products. Milk containing few bacteria is apt 

 to contain proportionately few or no harmful varieties. 

 The fact, however, is not to be ignored that a number of 

 serious milk-borne outbreaks have resulted from infection 

 in a " clean " milk containing comparatively few bacteria 

 of the ordinary kind. 



Most of the harmful bacteria which cause disease in 

 man grow best at the body temperature and not at all at 

 the low temperatures at which milk must be kept in order 

 to keep the total bacterial count down. 



Where the bacteria come from. The bacteria in milk come 

 from many different sources. Some of them are already in 

 the milk before it is drawn from the udder. Others get 

 into the milk from the dust in the air or fall into the milk 

 pail with the dirt from the cow. Still others are introduced 

 into the milk from the hands of the milker. A certain 

 number get into the milk from the milk pails, milk cans, 

 and other objects with which the milk comes in contact. 

 When a fly falls into milk it carries with it undesirable 

 parasites and possibly infection. The bacterial population 

 of a fly is from 550 to 155,000,000. 



Every time milk is handled there is an increase in its 

 bacterial content. Unless painstaking precautions are 

 observed, milk receives fresh bacterial contamination 

 ^ every time it is poured from one vessel to another, every 

 time it is stirred, tasted, uncovered, or handled in any way. 

 Separator milk may contain more bacteria than the original 

 milk and the same is true of filtered milk. Thus, milk 

 strained through gauze or cotton, or filtered through gravel 

 or any other device, while it looks cleaner, almost always 

 contains more bacteria than before it was "purified." 



