
BACTERIA IN THE DAIRY. 25 
became bitter none of the three inoculated samples showed the 
slightest trace of bitterness. Where the control cream showed 
a partial curdling, the inoculated samples showed an entirely 
independent effect that was evidently due directly to the influ- 
ence of the inoculated species and not to those left in the cream 
after pasteurizing. In some cases the inoculated cream was 
thickened and curdled from the effects of the bacteria with 
which it had been inoculated, but, in other cases, where the 
inoculated species had no power of curdling the cream, the 
cream at the end of the ripening was as thin as at the begin- 
ning, showing no trace of curdling even though the control . 
cream was at the same time very thick. ‘These results were 
not in one or two cases, but in a great number of experiments. 
The result at first surprised me, but it was found to be so gen- 
eral that I soon came to look upon it as normal and to expect it. 
WHY ‘‘STARTERS’’ ARE BENEFICIAL. 
The importance and significance of this fact is considerable. 
If the control develops a bitter taste, while the inoculated species 
does not, this can only be because certain bacteria grow in the 
control which do not grow to an equal extent in the inoculated 
cream. When cream is inoculated with one kind of bacteria 
in considerable quantity, other species of bacteria already 
present may be checked in their development by the growth of 
the inoculated species and prevented from producing their 
normal results. ‘She control and the inoculated cream must 
have had at the end of pasteurization the same kind of bacteria 
present, but the inoculation of the cream with one species of 
bacteria in the artificial culture prevented those in the cream 
either from growing or from having their normal effect upon 
the cream. 
This result is, indeed, not very surprising after all. Bac- 
teriologists have for some time known that different species of 
bacteria may thus have a repressing influence upon each other. 
It has been determined, for instance, that the growth of the 
normal bacteria in milk prevents the growth there of the 
cholera bacillus, although the cholera bacillus will grow readily 
in milk that has been sterilized. Many other similar instances 
have been found, indicating that this is not an unusual but 
rather a common effect where different kinds of bacteria are 
