SO-CALLED GERMICIDAL PROPERTY OF MILK. 89 
eee oO) CALLED GERMICIDAL PROPERTY” OF 
| MILK. 
BYGWee STOCKING 41k, 

[In the preparation of this report credit is due to Dr. H. W. Conn for aid in planning 
and conducting the investigation. | 
MILK AS A FOOD. 
The high nutritive value of milk as a human food is recog- 
nized by all, and does not need to be emphasized. Milk may 
be consumed as a fresh article, or it may be made into butter, 
cheese, and other manufactured products. The larger part, 
however, is used for consumption in its natural form. Milk 
that is to be used for direct consumption must reach the con- 
sumer in as nearly its natural condition as possible; that is, the 
condition in which it leaves the udder of a healthy cow. Every 
one who is at all familiar with milk knows that if left to itself, 
certain changes take place within the next few hours after it 
is drawn from the cow. ‘The most noticeable of these changes 
is the souring and curdling, a phenomenon so common that all 
milk handlers and consumers are familiar with it. There are 
also other changes which take place, which affect the odor and 
taste and sometimes the appearance of the milk, even though 
it does not taste sour or appear to be curdled. 
During the last few years these various changes in milk have 
been subject to a large amount of study and investigation, and 
it is now known that a large part of them, at least, are due 
to the presence and growth of bacteria in the milk. The prac- 
tical problem, then, for the dairyman and milk dealer as well 
as the milk consumer is to so produce and care for the milk 
that the entrance and development of bacteria will be reduced 
to the minimum. 
MILK CONTAMINATED IN THE UDDER. 
Milk as it is secreted in the glands of the healthy udder is 
free from all micro-organisms. Recent investigations, how- 
ever, have shown that the milk becomes more or less filled 
7 
