eam sometimes pollute their
udders and so indirectly infect the milk. Such outbreaks rarely
persist for any considerable length of time as the common acid
organisms soon regain the ascendency.

Creameries and cheese factories are sometimes troubled with
sliminess in starters. This seems to be due to some change which the
ordinary lactic acid bacteria undergo on long propagation rather
than to contamination of the starter. There are, however, types of
acid-producing bacteria that are able to form specific substances in
milk that are slimy in character. Two of these forms of slimy milk
are of economic importance. The slimy whey (lange Wei) of Holland
is added to milk in the manufacture of Edam cheese, apparently
serving the same purpose as the addition of the pure culture starter
in cheddar cheese making. In Norway, a sour, slimy milk
(taettemjolk) is used as food. It is produced by the addition of
some previously fermented milk. This beverage is also used in some
of the Norwegian settlements of Wisconsin, the original seed having
been brought from Norway, and the bacteria maintained by constant
propagation from one sample of milk to another. The milk has the
odor and taste of butter milk, but is not especially appetizing in
appearance to any one not accustomed to it; it is, however, as
harmless to health as is any other form of sour milk. It is not
known that any of these forms of slimy milk are distinctly harmful
to the quality of butter or cheese.

=Alcoholic fermentation of milk.= The bacteria as a class are
incapable of producing alcohol in appreciable amounts. The alcoholic
beverages, beer, wine, and cider, are produced by the growth of
yeast, in such sugar containing liquids as fruit juices, extracts of
grains, etc. The common types of yeasts are incapable of acting on
milk sugar, but they can ferment glucose, maltose, and cane sugar,
forming equal amounts of alcohol and carbonic acid gas, which causes
the effervescence of fermented and carbonated drinks. There are,
however, some types of yeasts found in milk and its products that
are able to ferment milk sugar.

All yeasts grow best in an acid medium, hence those fermenting milk
sugar find suitable conditions for growth in sour milk or whey. They
may at times become of economic importance in the cheese industry,
because of the contamination of the milk with large numbers of
them. The arrangement of the whey vat is often such that it cannot
be completely empti