164 BACTERIA IN MILK 
number of kinds exceeds the number of lactic acid bacteria. They 
are found commonly in the dairy, especially in the dust and filth 
that get into the milk. Practically every sample of fresh milk 
will contain them in greater or lessnumbers. Butitis very doubt- 
ful whether this type of bacteria is of much or of any significance 
in ordinary dairying. Although the varieties may be numerous 
and their number may be great in fresh milk, they very rarely get 
an opportunity to have any considerable effect upon the milk. 
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A E F G 
Fic. 34.—-Gelatin stab cultures. e,f, and g, show liquefaction; a, filiform; b, beaded; 
c, villous; d, arborescent; e, napiform; f, infundibuliform; g, stratiform. 
The lactic bacteria grow so very much more rapidly that they soon 
entirely outnumber the enzyme class, and, indeed, in most cases 
stop their growth. As a result, whereas the latter may be com- 
paratively numerous in fresh milk, they become less rather than 
more abundant as the lactic bacteria grow, and finally disappear. 
Under such conditions their significance in the milk is probably 
nothing. Occasionally, however, it may happen that a sample of 
milk does not chance to have any lactic organisms in it, or that 
they are so few as to fail to get the upper hand of the others. If 
this occurs, the other species of bacteria may find the conditions 
favorable to their growth, as in cases of sweet curdling. This 
class of bacteria plays an important part in the changes which 
may take place in so-called sterilized milk, which has been heated 
