was almost wholly replaced by a bitter type.

Storage of milk at very low temperatures is conducive to the
appearance of a bitter taste in milk, the explanation in this case
being that the acid-forming bacteria are unable to grow at a low
temperature, while some of the putrefactive forms can multiply and
develop these astringent or bitter by-products.

=Miscellaneous fermentations of milk.= There are a number of other
abnormal fermentations in milk that occur so rarely as to be of but
little economic importance. Some, as the colored milks, are however,
quite striking, and on this account have had much attention directed
to them in the past. There are bacteria that are able to produce
various colored substances, such as red, yellow, and blue. In case
milk becomes seeded with large numbers of any of these kinds, it is
very likely to be colored by the growth. Red milk may be due to
bacteria, but more frequently is caused by the actual presence of
blood in the milk, due to a wound in the udder, or the effect of a
severe case of inflammation of this gland. Such a condition may be
readily distinguished by allowing the milk to stand for a short
time, in which case, if due to blood, the red corpuscles will soon
settle to the bottom of the container, while bacterial troubles
producing a red coloration are more evident on the surface.

It is also claimed that certain bacteria may impart a soapy taste or
turnip flavor to milk.

=Cycle of fermentations in milk.= If a sample of milk is allowed to
stand, it will undergo a certain sequence of fermentations that well
illustrates the principle that one type of organisms is dependent on
some other type to furnish suitable conditions for its development.
This cycle of changes that normally occurs in milk is as follows:
(1) The bacteria that come from the interior of the udder are the
first to develop, but usually the change they produce is not
evident.

(2) Of the types that gain admission, subsequent to the milking, the
acid-producing species are able to adjust themselves most perfectly
to the conditions that obtain in milk. Within a few hours they
greatly predominate and soon the milk curdles under the production
of acid. Their growth, however, is soon stopped by the accumulation
of their own by-products.

(3) The semi-solid curdled milk, on account of its acid reaction
then becomes a favorable medium for the growth of molds; a prevalent
form, known as _Oidium lactis_ usually d