
APPLICATIONS OF BACTERIOLOGY IN EUROPE. 67 
SOME PRACTICAL APPLICATIONS OF BAC- 
TERIOLOGY IN EUROPEAN DAIRYING. 
BY H. W. CONN. 
I. BACTERIOLOGY AND THE MILK SUPPLY IN EUROPEAN 
CITIES, 
It is now about a dozen years since bacteriologists have 
turned especial attention to the subject of dairy bacteriology. 
During that time a large amount of information interesting to 
the scientist has been obtained, and this information has ac- 
cumulated with especial rapidity in the last few years. Al- 
though the subject has been studied chiefly from a scientific 
standpoint, it is natural to expect that some facts have been 
discovered which might be put to practical use in dairying. 
This has been found to be the case, and in many respects the 
dairying industry has been very decidedly changed, if not 
almost completely revolutionized, by the application of facts 
which have been discovered in connection with dairy bacteri- 
ology. These changes have, of course, occurred somewhat 
rapidly. Atthe same time they have occurred in such an un- 
pretentious way that most people hardly realize the extent to 
which dairy methods have been modified by facts discovered 
along these lines. The present paper will review certain 
aspects of the dairying industry in Europe for the purpose of 
illustrating how our modern methods have been influenced 
by dairy bacteriology. 
CHIEF DISCOVERIES OF DAIRY BACTERIOLOGY. 
The facts discovered in relation of bacteria to milk are very 
numerous, some of them having very highly important prac- 
tical bearings and others having only scientific interest. In 
order to understand our subject more accurately it will be 
necessary, in the first place, to summarize the important facts 
which dairy bacteriology has disclosed, even though these 
facts may be familiar to everyone. The more important dis- 
coveries which have resulted from this line of study are as 
follows: 
First, pure milk as secreted from the gland of the healthy 
animal, if kept free from external contamination, will not sour 
