ough a minute description of cultural
characteristics is not given it would seem to be related to _Bacillus_
or _Lactobacillus caucasicus_.

_Leben Raib_ or _Leben_ (_Laban._)--This is a beverage prepared largely
by the Egyptians, and differs from keffir, as does matzoon, in
possessing a characteristic aroma and taste. It differs also from the
former by having only a very weak alcoholic fermentation, and by the
coagulum being coarse and lumpy instead of being extremely fine. It is
made from buffaloes', goats', or cows' milk by the addition of roba (or
old leben) to the previously boiled and cooled fresh milk. The use of
leben is many centuries old, and it is used in Egypt as in Arabia for
medicinal purposes, although that of the Syrians and Arabians is said to
differ from that of the Egyptians and Algerians. The fermentative
changes occurring in the formation of the Egyptian leben have been
investigated by Rist and Khoury,[64] and also by Guerbet,[65] who found
that five organisms were normally present. These comprised a
chain-forming bacillus (_Streptobacillus_), a second smaller bacillus
(_Bacillus lebenis_), a diplococcus, a saccharomyces, and a mycoderma.
Of these five organisms, it would appear that four live in metabiosis,
the streptobacilli and bacilli hydrolyse the milk sugar, the components
of which are split up by the yeast to alcohol and carbon-dioxide. The
alcohol thus formed, together with the glucose formed by hydrolysis, are
eventually converted to acid or combusted by the mycoderma species. The
leben thereby assumes the sharp, unpleasant flavour met with in old
samples. The diplococcus merely produces acidification and coagulation
of the milk. Rist and Khoury were able, by the use of these organisms,
to produce normal leben, especially when the true yeast was allowed to
grow in the milk for some time before inoculation with the other
organisms was made.

Some of the half-civilised tribes of Siberia, the Tartars and the
Burgaten, prepare a strong alcoholic beverage, araka or ojran, from
fermented milk. This is really a product of distillation, and contains
seven to eight per cent. of alcohol and volatile fatty acids.

[Illustration: FIG. 13--Photo-micrograph of preparation
from Armenian soured milk (Matzoon). This is related to
Yoghourt, and contains, as will be seen from the above
photo, yeasts, streptococci, diplococci, and a bacillus
with the morphology of _Bacillus bulgaricus._ This, and