Judith Gap journal. [volume] (Judith Gap, Mont.) 1908-19??, 1911-08-25
BACTERIA IN MILK.
BY D. B. Swinqle, 6otanist and
6acterioIoQist, Montana A.
ricultural College.

+ 1. + i. j. + j. j. !. !. + + + + I. i.
That milk may be either an excel
lent food, a sour, distasteful mass. or
even deadly poison, has long been
known. That the difference is brought
about by bacterial action is now we'll
recognized. but there are still many
facts and principles concerning the
relations of bacteria to milk that arc
not clear in the public mind.
Milk in the cows udder is some.
times free from all germ life. but such
Is not always the case. Often Mi
crobes become established there ard
multiply for an indefinite period AT
the time 1t is used milk may contain
from several thousands to several
millions in every spoonful
Almost everything that drops into
Or touches milk-dust. bits Of dirt.
manure. hair. etc.-carries in bacteria.
Pals, cans, and strainers that are
BADLY washed or that become soiled or
dusty after washing. contribute their
share. The number from direct con-
tamination would not however. be OK
cessive as rule, If they were not al
lowed to multiply afterward. Milk is
an excellent food for bacteria and with
suitable temperature they multiply
rapidly. Some kinds under such con-
ditiOns double in number every TWEEN.
ty minutes. Close to the freezing
temperature they do not multiply Mt
all; at 40 degrees F. they multiply
but slowly. but at summer heat they
increase with enormous rapidity
Kinds Found in MIX.
Many kinds occur in almost every
sample. Some have little effect that
we can notice. others change the milk
sugar to tactic acid and thereby cause
ii to sour. while still others produce
sickness aud even death. Unfortu-
nately SO many kinds are so much
alike in appearance that It Is very
difficult to tell by direct examination
which are good and which are bad.
Such distinction can be made In
most cases. but it requires a long
and difficult study. not practicable II
many samples are being examined.
The objection has ben raised. there
fore, that counting tho whole number
OF bacteria In sample is test that
means nothing, but let lis see.
Significance Of the Numbers.
II there are very few 1t means that
the milk is being properly cared for,
provided. of course. that no preservA-
tlves are used. II. on the other hand.
the number is high. 1t means that
there is improper handling. usually
one Of four things:
First-Dirt gets in while milking
IL going on.
s<alded out
Third-The milk Is not cooled
promptly and kept cold.
Fourth-Too long a time has elapsed
since it was drawn.
Under practical commercial condi-
tons dairymen do not always know
whether the milk is handled with suf-
fcient care or not. Counting the bac-
terra will tell and the dairymen can
act accordingly. Some have jumped
to the conclusion that because most Of
the bacteria in milk are harmless, all
are harmless. and it does not make
any difference whether the milk is
we'll cared for or not. provided 1t does
not sour. To those we will say that
it has been abundantly proved that
under these conditions there very
often appear kinds that cause intes-
final troubles and thousands Of deaths
annually. especially among children.
A large proportion of these deaths
could have been prevented by proper
care.
The Tuberculosis Germ.
This organism gets into milk in
three ways principally: From the
dirt Of stables where tuberculous ami
mails are kept; from tuberculOus peO-
pie handling the milk. and from the
udders of tuberculous COWS. Concern
ing the latter. ii is better to have the
animals tested with tuberculin than to
have the milk examined for the germ.
Ii the milk is examined and the germs
are found. the case is clear, but ii
they are not found it may be that the
COWS are healthy. that they have the
disease but give off so few germs that
they We're overlooked. or that none
We're given off in that sample but may
be released at some future milking.
In the majority of eases where the
uCder Itself is not tuberculOus no bac-
terra of this kind are drawn with the
milk, but no one can predict when the
fatal change will take place. The
tuberculin test is. therefore, much
preferable to examination OF the milk.
T. Pasteurization.
This process of mild heating kills
all the more delicate organisms. in
Guiding that which causes tuberculO-
sis, but does not make the milk en-
tirely sterile. 1t makes bad milk less
dangerous, but harder OF digestion 1t
is improved, in way, but is not near
ly so good. especially for children. as
that which has been kept clean and