APPLICATIONS OF BACTERIOLOGY IN EUROPE. 87 
lesson. Danish butter-makers stand at the head of the pro- 
fession for the world. Danish butter commands the highest 
price and has the highest reputation of all butters. The Danes 
themselves adopt with practical uniformity the use of pure 
cultures, and the undoubted inference to be drawn from this 
is that the use of pure cultures in cream ripening is not only 
practical, but it results in uniform advantage. 
The pure cultures that are used in the different dairies in 
Denmark, however, are not all alike. There are several of 
them for sale in dairy districts, and different cultures contain 
quite different species of bacteria. Most of them are really 
pure cultures, that is, masses of a single species of bacteria. 
Some of them, however, are mixtures of different bacteria, and 
one at least contains no less than ten or a dozen different 
species of bacteria mixed together. Such a mixture is not an 
artificial one, but is obtained simply from some natural starter. 
Doubtless in the action of such a mixture some of the bacteria 
have no influence at all in the process of cream ripening. 
The actual operations in the Danish creamery may be in- 
teresting to describe in some detail, inasmuch as they illustrate 
so well how all of the lessons from bacteriology are brought 
_ together and applied. A typical Danish creamery, then, may 
be described somewhat as follows: The milk is brought to 
the creamery in large cans. As soon as it reaches the 
creamery it is placed in a large receiving vessel and warmed 
to a moderate temperature, about 25° C. From this receiving 
vessel it passes directly into a separator, and the skim-milk and 
‘the cream are received in separate compartments. The skim- 
milk is immediately pumped from the receiving vessel into a 
large receptacle surrounded by steam coils, through which 
steam is passing constantly. In this receptacle the skim-milk 
is heated to a temperature of 175° (80° C.), the milk in the 
receptacle being kept constantly at this temperature. As it 
is being constantly pumped in it is also being constantly 
drawn out into the milk cans of the farmer, who takes this 
heated milk and carries it back to his farm for use in feeding 
calves and pigs. The skim-milk is in this way pasteurized for 
the purpose of neutralizing the danger of distributing tuber- 
culosis. ie 
The cream which comes from the separator is elevated by 
mechanical contrivances into a smaller receptacle, which is 
also surrounded by steam coils, and in this receptacle the 
cream is also heated to a temperature of about 175° (SOCT Gy 
