potency. But this is now known to be not the true remedial process
with respect to the zymotic germs. The most wonderful achievement of
recent investigation reveals a philosophy of both bane and antidote
that astonishes us with its simplicity as much as with its efficiency.
At the moment when humanity stands aghast at the announcement that
germs are not destroyed by disinfectants, comes the counter discovery
that they are rendered harmless by oxygen. It seems that it makes no
difference, really, of what sort or from what source are the bacteria
that we take into the blood. The only material difference to us
depends on _the sort of atmosphere_ in which their hourly generations
are bred. For example, the bacteria _developed in confined air_, from
a simple infusion of hay, are found by experiment to be as capable of
generating that most terrible of blood poisoners, the malignant
pustule, as are the bacteria taken from the pustule itself.

On the other hand, the bacteria from the malignant pustule itself,
after propagating for a few hours in pure and free air, become a
perfectly harmless race, and are actually injected into the blood
with impunity. The explanation of the strange discovery is this--note
its extreme simplicity--bacteria bred in copious oxygen perish for
want of it as soon as they enter the blood vessels; whereas those
inured to an unventilated atmosphere for a few generations, which
means only a few hours, are prepared to thrive and propagate
infinitely within our veins; and that is the whole mystery of blood
poisoning and zymotic diseases. Taken in connection with the narcotic
or _nerve-poisoning_ power of carbonic acid (to which all the classes
of diseases resulting from colds are due), we have also in this simple
but grand discovery the whole mystery of the question with which we
set out--why free air is health, and why sickness is a purely domestic
product. The restitution of natural health to mankind demands only,