86 STORRS AGRICULTURAL EXPERIMENT STATION. 
As is well known, the study of bacteriology has turned the 
attention of butter-makers primarily to the process of cream 
ripening. It has shown them that in the proper ripening of 
the cream lies the secret of obtaining the best quality of butter. 
It has shown them that under usual conditions this cream 
ripening is largely a matter of chance. It has proved that the 
quality of the product is in considerable degree dependent upon 
the particular kind of bacteria which may ripen the cream, 
and has shown that by natural processes the butter-maker is 
unable to be sure of obtaining the desirable species. These 
facts are well known, but the practical application of them 
has not been very widely extended in any European country 
except Denmark and northern Germany. 
PURE CULTURES IN DENMARK. 
It was in Denmark, however, that the practical application 
of this subject was first made. The reputation of Danish 
butter is well known. It stands, without question, at the head 
of all types of European butter. Danish butter is exported in 
very large quantities, is sold at the highest prices in foreign 
markets. This reputation has always adhered to the butter of 
Denmark, and within the last ten years, since the application 
of bacteriological methods of butter-making, the reputation of 
the butter has not fallen, but has increased. 
It was in Denmark that the first attempt was made to use 
what are now known as pure cultures for cream ripening. 
Under the influence of the Danish bacteriologist, Prof. Storch, 
there was introduced into the Danish creameries a method of 
ripening cream through the agency of artificial bacteria cul- 
tures. The method was moderately successful and gradually 
extended. From Denmark it was adopted in the dairying 
countries in northern Germany, and from these places it has 
in isolated instances extended to other countries. But even 
to the present day it is only in these two countries where the 
use of this method has been adopted in anything more than 
exceptional instances. In other countries, pure cultures are 
used only when the butter-maker has trouble with his butter. 
In Denmark, however, the use of pure cultures has become 
very common. It is stated that over 95 per cent. of the butter 
made in this great butter-making country at the present time 
is made by the agency of artificial cultures used in cream ripen- 
ing. This percentage is surprising, and conveys a very great 

