an_, have confirmed the latter fact, which now may be
taken as certain. The action of kephir in preventing intestinal
putrefaction depends on the lactic acid bacillus which it contains.
Kephir, although in some cases certainly beneficial, cannot be
recommended for the prolonged use necessary, if intestinal putrefaction
is to be overcome.... Professor Hayem prohibits its use in the case of
persons in whom food is retained for long in the stomach. When it is
retained in the stomach, kephir goes on fermenting, and there are
developed in the contents butyric and acetic acids, which aggravate the
digestive disturbances. Kephir is produced by combined lactic and
alcoholic fermentations ... and it is the lactic and not the alcoholic
fermentation on which the valuable properties of kephir depend; it is
correct to replace it by sour milk, that contains either no alcohol or
merely the smallest traces of it. The fact that so many races make sour
milk and use it copiously is an excellent testimony of its usefulness."

There are two methods given by Fluegge[29] for the preparation of keffir:

"In the first, the dry brown kefir grains of commerce are allowed to lie
in water for five or six hours until they swell; they are then carefully
washed and placed in fresh milk, which should be changed once or twice
a day until the grains become pure white in colour and when placed in
fresh milk, quickly mount to the surface--twenty to thirty minutes. One
litre of milk is then poured into a flask, and a full tablespoonful of
the prepared _koerner_ added to it. This is allowed to stand open for
five to eight hours; the flask is then closed and kept at 18 deg. C. It
should be shaken every two hours. At the end of twenty-four hours the
milk is poured through a fine sieve into another flask, which must not
be more than four fifths full. This is corked and allowed to stand,
being shaken from time to time. At the end of twenty-four hours a drink
is obtained which contains but little carbon-dioxide or alcohol. Usually
it is not drunk until the second day, when, upon standing, two layers
are formed, the lower milky, translucent; and the upper containing fine
flakes of casein. When shaken it has a cream-like consistence. On the
third day it again becomes thin and very acid. The second method is used
when one has a good kefir and two or three days to start with. Three or
four parts of fresh cows' milk are added to one part of this and poured
into flasks