a starter composed of a distinctively lactic acid-producing
organism than with a form which is less capable of thriving vigorously
in milk, and it should be said that these impurities can frequently be
eliminated by continued propagation.

The virility and vigor of the starter is also a fluctuating factor,
dependent in part at least, upon the conditions under which the organism
is grown. In some cases the germ is cultivated in solutions in which
acid cannot be formed in abundance. Where the conditions permit of the
formation of acid, as would be the case if sugar was present with a
lactic acid-producing species, the vitality of the culture is often
impaired by the action of the gradually accumulating acid. Some
manufacturers attempt to minimize this deleterious condition by adding
carbonate of lime which unites with the acid that is formed.

~Propagation of starters for cream-ripening.~ The preparation and
propagation of a starter for cream-ripening is a process involving
considerable bacteriological knowledge, whether the starter is of
domestic origin or prepared from a pure-culture ferment. In any event,
it is necessary that the starter should be handled in a way so as to
prevent the introduction of foreign bacteria as far as possible. It
should be remembered at all times that the starter is a live thing and
must be handled throughout its entire history in a way so as to retain
its vitality and vigor unimpaired. The following points should be taken
into consideration in growing the starter and transferring it from day
to day:

1. If a commercial starter is used, see that it is fresh and that the
seal has not been broken. If the culture is too old, the larger part of
the organisms may have died out before it is transferred, in which case
the effect of its addition to the sterilized milk would be of little
value.

When the commercial ferment is received, it should be stored in the
refrigerator pending its use so as to retard as much as possible the
changes that naturally go on in the culture liquid. Be careful that the
bottle is not exposed to the influence of direct sunlight for in a
transparent medium the organisms may be readily killed by the
disinfecting action of the sun's rays.

2. If a home-made starter is employed, use the greatest possible care in
selecting the milk that is to be used as a basis for the starter.

3. For the propagation and perpetuation of the starter from day to day,
it is necessary that