ber of cases of bitter milk have, however, been traced
to bacterial origin. For a number of years the bitter fermentation of
milk was thought to be associated with the butyric fermentation, but
Weigmann[67] showed that the two conditions were not dependent upon each
other. He found that the organism which produced the bitter taste acted
upon the casein.

Conn[68] observed a coccus form in bitter cream that was able to impart
a bitter flavor to milk. Sometimes a bitter condition does not develop
in the milk, but may appear later in the milk products, as in the case
of a micrococcus which Freudenreich[69] found in cheese.

Harrison[70] has traced a common bitter condition in Canadian milk to a
milk-sugar splitting yeast, _Torula amara_ which not only grows rapidly
in milk but produces an undesirable bitterness in cheddar cheese.

Cream ripened at low temperatures not infrequently develops a bitter
flavor, showing that the optimum temperature for this type of
fermentation is below the typical lactic acid change.

Milk that has been heated often develops a bitter condition. The
explanation of this is that the bacteria producing the bitter substances
usually possess endospores, and that while the boiling or sterilizing of
milk easily kills the lactic acid germs, these forms on account of their
greater resisting powers are not destroyed by the heat.

~Soapy milk:~ A soapy flavor in milk was traced by Weigmann and Zirn[71]
to a specific bacillus, _B. lactis saponacei_, that they found gained
access to the milk in one case from the bedding and in another instance
from hay. A similar outbreak has been reported in this country,[72] due
to a germ acting on the casein and albumen.

~Red milk.~ The most common trouble of this nature in milk is due to
presence of blood, which is most frequently caused by some wound in the
udder. The ingestion of certain plants as sedges and scouring rushes is
also said to cause a bloody condition; madders impart a reddish tinge
due to coloring matter absorbed. Defects of this class can be readily
distinguished from those due to germ growth because they are apparent at
time of milking. Where blood is actually present, the corpuscles settle
out in a short time if left undisturbed.

There are a number of chromogenic or color-producing bacteria that are
able to grow in milk, but their action is so slow that generally they
are not of much consequence. Moreover their development is usually
confined