TYPES OF BACTERIA FOUND IN MILK. 153 



Neutral Types. Among the normal milk bacteria there are 

 many that appear to have no noticeable action on milk. They 

 produce no acid and, apparently, no enzyme. When they grow 

 in milk they produce no noticeable effect upon it. So far as we 

 can see they are of no significance in dairying. Nor do we have 

 any reason for believing that they have any pathogenic effect upon 

 persons drinking the milk. They are, therefore, simply classed as 

 neutral types, and need not here be further considered. 



ABNORMAL MILK BACTERIA. 



The types of milk bacteria included under this head differ 

 from those already considered merely in the fact that they are 

 comparatively rare. Whereas milk will practically always sour 

 through the agency of the lactic bacteria and will nearly always 

 contain bacteria of the peptonizing class, the following kinds of 

 bacteria are not commonly found. Most of them are occasionally 

 the cause of troublesome dairy infections. When they occur in 

 milk, in numbers sufficient to cause troublesome changes, they 

 may always be regarded as coming from some unusual source of 

 contamination, one which may be prevented. While souring of 

 milk cannot be prevented by any practical means, because of the 

 universal distribution of lactic acid bacteria, these types of 

 troublesome infections may be prevented if sufficient care is taken 

 in regard to cleanliness, and they may be checked if the dairy- 

 man simply learns whence the contamination arises. For these 

 reasons, in practical dairying, it is a matter of special importance 

 to understand their sources. 



Slimy Milk. Slimy milk is not an uncommon trouble in the 

 dairy. It is sometimes produced by a diseased condition of the 

 cow, slimy milk being a common characteristic of garget. In 

 such cases the milk is slimy when drawn. Such milk is certainly 

 not fit to drink. 



In other cases the milk is not slimy when drawn, but appears 

 like normal milk. * After a few hours, at about the time when 

 milk would usually sour, instead of becoming acid in the normal 



