BACTERIA IN BUTTER-MAKING 201 
starting the ripening; but to-day almost all good creameries use 
starters, not so much for starting, as for regulating the ripening. 
Prof. Storch, of Copenhagen, first conceived the possibility 
of furnishing to butter-makers cultures of the proper species of 
bacteria, which they might add to their cream for the purpose of 
ripening, somewhat as yeast is used in brewing. This experi- 
menter not only conceived the method, but put it into practical 
operation in Denmark. His method consisted (1) in pasteur- 
izing the cream at about 105°F., for the purpose of destroying most 
of the bacteria that might be present, and (2) in adding to ita pure 
culture of bacteria, whose valué in producing a good flavor had 
been determined by experiment. This method is, of course, 
logically satisfactory, for, since pasteurization destroys most of the 
bacteria present in the cream, it follows that the ripening will be 
produced by the species of bacteria introduced by the adding of 
the pure culture. Professor Storch was soon followed by other 
experimenters and the method adopted in Copenhagen was ex- 
tended more or less widely in north Germany and Denmark. 
In Denmark it is now used almost universally, and in north 
Germany quite widely, in general dairying. 
In the United States the use of pure cultures for cream-ripen- 
ing has had a somewhat different history. It was introduced to 
dairymen shortly after its development in Copenhagen, but for 
some time little attention was paid to it, so that it was hardly 
brought to the notice of the ordinary butter-maker. Our butter- 
makers were not in condition to pasteurize their cream. In 1895 
a slight change was madein the process. In order to bring the sub- 
ject more widely to the attention of dairymen, a method was sug- 
gested of using the cultures without previously pasteurizing the 
cream. This seemed illogical, since the cream is already filled 
with bacteria, and the addition of a new culture could hardly be 
supposed to give entirely satisfactory results. But when we 
remember how a vigorous lot of lactic acid bacteria can over- 
come other species, the method does not appear so illogical after 
