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 
