s
frequently responsible for a continuance of trouble of this sort.

The slimy substance formed in milk comes from various constituents of
the milk, and the chemical character of the slime produced also varies
with different germs. In some cases the slimy material is merely the
swollen outer cell membrane of the bacteria themselves as in the case of
_B. lactis viscosus_; in others it is due to the decomposition of the
proteids, but often the chief decomposition product appears to come from
a viscous fermentation of the milk-sugar.

An interesting case of a fermentation of this class being utilized in
dairying is seen in the use of "lange wei" (long or stringy whey) which
is employed as a starter in Holland to control the gassy fermentations
in Edam cheese. This slimy change is due to the growth of
_Streptococcus Hollandicus_.[63]

~Alcoholic fermentations.~ Although glucose or cane-sugar solutions are
extremely prone to undergo alcoholic fermentation, milk sugar does not
readily undergo this change. Where such changes are produced it is due
to yeasts. Several outbreaks attributable to such a cause have been
reported.[64] Russell and Hastings[65] have found these milk-sugar
splitting yeasts particularly abundant in regions where Swiss cheese is
made, a condition made possible by the use of whey-soaked rennets in
making such cheese.

Kephir and Koumiss are liquors much used in the Orient which are made
from milk that has undergone alcoholic fermentation. Koumiss was
originally made from mare's milk but is now often made from cows' milk
by adding cane sugar and yeast. In addition to the CO_{2} developed,
alcohol, lactic acid, and casein-dissolving ferments are formed. Kephir
is made by adding to milk Kephir grains, which are a mass of yeast and
bacterial cells. The yeasts produce alcohol and CO_{2} while the
bacteria change the casein of milk, rendering it more digestible. These
beverages are frequently recommended to persons who seem to be unable to
digest raw milk readily. The exact nature of the changes produced are
not yet well understood.[66]

~Bitter milk.~ The presence of bitter substances in milk may be ascribed
to a variety of causes. A number of plants, such as lupines, ragweed and
chicory, possess the property of affecting milk when the same are
consumed by animals. At certain stages in lactation, a bitter salty
taste is occasionally to be noted that is peculiar to individual
animals.

A considerable num