gO STORRS AGRICULTURAL EXPERIMENT STATION. 
with bacteria before it is drawn from the udder. This con- 
tamination is made possible by reason of the fact that bacteria 
are able to gain access through the orifice of the teat, thus 
working their way through the ducts into the various parts of 
the udder. So universal is this udder contamination, that it is 
a practical impossibility to obtain milk in a sterile condition. 
Milk, therefore, may contain quite appreciable numbers of bac- 
teria when it is drawn from the cow; but experiments con- 
ducted at this Station and at other places seem to show quite 
conclusively that the organisms which normally exist in the 
milk while it is still in the udder produce but slight effects 
upon the milk, even when it is kept for a number of hours at 
comparatively warm temperatures. By far the larger part of 
the bacteria found in milk as it reaches the consumer gain 
access from external sources, and it is due to the presence and 
growth of these that the milk undergoes the process of sour- 
ing, changes in taste and odor, and various decomposition pro- 
cesses. During the past few years a large amount of study 
and investigation has shown that milk is an excellent medium 
for the growth of a great variety of species of bacteria. Asa 
result of this, it has become a generally accepted opinion that 
practically all species of bacteria that gain access to the milk 
thrive and multiply in it, the rate at which the multiplication 
takes place being dependent on the temperature at which the 
milk is kept. .The commonly accepted idea has been that the 
bacteria which are in the milk at the time it is drawn begin 
immediately to multiply with great rapidity. In order to pre- 
vent this enormous increase, the common practise is to cool the 
milk more or less thoroughly as soon as possible and then keep 
it at as low a temperature’ as circumstances permit. In con- 
trast with this generally accepted opinion, certain investigators 
have from time to time made the statement that for a certain 
length of time the number of bacteria decreases, so that milk 
when a few hours old contains a smaller number of organisms 
than it did when first obtained. This fact was stated by Fok- 
ker in 1890, by Freudenreich in 1891, and by Freeman in 1896. 
‘These men simply observed that the number of organisms was 
frequently smaller when the milk was a few hours old than 
when first drawn, and simply made the statement that ‘‘freshly 
drawn milk contains a germicidal action,’’ but made no attempt 
to determine the extent of this action or to explain the cause 
of the phenomenon. 
