of sanitary reform, we are painfully aware that the most
frequent causes of human disease are the accumulations about us of the
waste products of our own kitchens, barns, and factories. The "bad air"
which we hear so frequently and justly denounced as a cause of disease,
is air which we have ourselves polluted. This same process has been
going on within the body for millions of years. No sooner did three or
four cells begin to cling together, to form an organism, a body, than
the waste products of the cells in the interior of the group began to
form a source of danger for the others. If some means of getting rid of
these could not be devised, the group would destroy itself, and the
experiment of cooeperation, of colony-formation, of organization in fact,
would be a failure.

Hence, at a very early period we find the development of the rudiments
of systems of body-sewerage, providing for the escape of waste poisons
through the food-tube, through the kidneys, through the gills and lungs,
through the sweat glands of the skin. So that when the body is
confronted by actual disease, it has all ready to its hand a remarkably
effective and resourceful system of sanitary appliances--sewer-flushing,
garbage-burning, filtration. In fact, this is precisely what it does
when attacked by poisons from without: it neutralizes and eliminates
them by the same methods which it has been practicing for millions of
years against poisons from within.

Take, for instance, such a painfully familiar and unheroic episode as an
attack of colic. It makes little difference whether the attack is due to
the swallowing of some mineral poison, like lead or arsenic, or the
irritating juice of some poisonous plant or herb, or to the every-day
accident of including in the menu some article of diet which was
beginning to spoil or decay, and which contained the bacteria of
putrefaction or their poisonous products. The reaction of defense is
practically the same, varying only with the violence and the character
of the poison. If the dose of poisonous substances be unusually large or
virulent, nature may short-circuit the whole attack by causing the
outraged stomach to reject its contents. The power of "playing Jonah" is
a wonderful safety-valve.

If the poison be not sufficiently irritating thus to short-circuit its
own career, it may get on into the intestines before the body thoroughly
wakes up to its presence. This part of the food-tube being naturally