138 The Australasian Scientific Magazine. [Nov. i, 1885. 
Milk may be taken from a cow direct into a flask, the flask plugged with 
cotton wool, and the milk kept for an indefinite period without under- 
going any change, and without producing any organisms. It used to be 
supposed that it is exposure to the air which causes milk to sour and 
curdle. This is not so. It is not the air, but the microscopic spores 
floating in the air, from which the organisms develop which bring about 
the changes. Tyndall’s researches have placed that beyond doubt. 
Lister hes shown that, if a flask be heated so as to kill any germs that are 
in it, and plugged before it commences to cool, and the cow is milked 
under certain precautions directly into the flask while the plug is 
momentarily removed and replaced, it is found no change occurs 
in the milk. The “precautions” are that the teats of the cow and 
the hands of the milker are washed with a fluid that destroys the germs. 
This is only an application in a particular case of the knowledge that if 
the organisms which cause fermentation in a certain fluid do not come in 
contact with that fluid the changes do not take place. Just also as if the 
orgenisms do not get wafted, or in some way pass to a fluid suited for 
their own growth, they do not develop, Tyndall has drawn an analogy 
with seeds and soils. If you sow radishes you do not get corn, and if you 
sow corn on unsuitable soil it will not grow. Though these micro- 
organisms are invisible to our unaided sight, they behave in the same 
way. You may inoculate a fluid with many organisms, and none may 
grow. The fluid may not be suitable. But a fluid suited to their develop- 
ment will not develop them unless they are introduced in some way 
natural or intentional. The matter so far is clear, and repeated 
observations by different experimenters only confirm the con- 
clusions arrived at. The extent of variation in growth according to the 
“ soils,” as the fluids are often called, on which the germs fall is a matter 
still for research. But the mystery of fermentation and of ferments is so 
far cleared up. Some ferments we regard as friends. They produce 
changes we desire. Some are our foes. They produce changes where 
we do not desire them. Bacterium lactis is one of these. The dragons 
of fairy tales that devour many champions fall at last to some observing 
knight who finds out the vulnerable point. We know that Bacterium 
lactis succumbs to a high temperature, and that among other things bich- 
loride of mercury is certain death. Though at present the applica- 
tion of the knowledge gained has not extended beyond the labor- 
atory, is it too much to hope it will be available in some form 
more generally? To know with clearness what has to be done 
is often the half-way to knowing how it is to be done. On a 
small scale, as mentioned above, it is possible to prevent milk from turn- 
ing bad for an indefinite length of time. Preventing it on a large scale 
must follow as surely as the thousands of miles of wire have followed 
laboratory researches on electricity. The means employed to combat 
micro-organisms may not be the same as at present employed. The great 
point so far gained is our knowing what it is that has to be combated. 
Much remains to be done, not only practically, but scientifically. 
When Pasteur was last in England, he mentioned to a friend that if 
he had three years to spare his greatest desire would be to spend them in 
the laboratory of some dairy working out the relation of germs to milk 
and cheese industry. 
M. S. W. 
