STARTERS, 221 
powder thoroughly mixed with the milk than it is to get the 
liquid cultures mixed. If anything is used with which to stir 
the sample, it should be sterilized before coming in contact 
with the milk. This applies in the preparation of all cultures. 
In testing or sampling the mother-starters, nothing should be 
allowed to come in contact with it unless it has previously been 
thoroughly sterilized. The powder cultures are usually more 
vigorous in their effect than most of the liquid cultures now 
on the market. The powder cultures usually coagulate the 
sample in about twenty-four hours, and if the operator is used 
to handling the liquid cultures, he should watch the mother- 
starters prepared from powder cultures, so that they do not 
get overripe. It is very essential that the starters do not get 
overripe. The time when the germs are most numerous and 
most active in the starter is about the time when the sample 
coagulates. As soon as this stage has been reached, or just 
previous to coagulation, the starter should be cooled down to 
at least 50° F., or lower if possible. This prevents any further 
growth of germs and the sample can be kept a short time 
without injury. 
Directions usually accompany each of the cultures, but the 
above will be found to produce good results with all of those 
mentioned in the above outline. 
By inoculating from 2% to 5% or more of the mother- 
starter into a large sample of pasteurized milk, any desired 
amount of starter can be prepared. In selecting this amount 
of milk, as much care as possible should be taken in order to 
select the best kind of milk, and keep it from being contaminated. 
When this large sample of starter is at the proper stage of 
coagulation, it should be’used at once, or else cooled down to 
about 50° F. The amount of mother-starter with which to 
inoculate the large sample of starter may vary a little with- 
out any bad effects. If the large sample of starter is to be 
ready for use in a short time, a larger portion of the mother- 
starter can be used for inoculation. If the temperature at 
which the starter is set and the amount of mother-starter used 
