166 BACTERIA IN MILK 
they do not sour the milk, and therefore deserve to be considered 
separately from the lactic acid bacteria. Under ordinary condi- 
tions they play no part in the changes that take place in milk. 
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 whendrawn. 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 
way, it becomes viscid, and finally it may be so slimy that it can 
be drawn out into long threads. At the same time it has a sweet- 
ish taste. Such milk is practically worthless. It cannot be used 
for butter-making, for the cream will not separate. It will not be 
