rged tonsils may prevent a
diphtheria epidemic. To detect in September those who are
undernourished, who have bad teeth, and who breathe through the mouth
will help forecast winter's outbreaks of scarlet fever and measles. One
dollar spent at this season in examination for soil hospitable to
disease germs may save fifty dollars otherwise necessary for inspection
and cure of contagious diseases.

It is harder at first to interest a community in medical examination
than in medical inspection, because we are all afraid of "catching"
diseases, while few of us know how they originate and how they can be
prevented by correcting the unfavorable conditions which physical
examination of school children will bring to light.

Courses in germ sociology are therefore of prime necessity. How do
germs act? On what do they live? Why do they move from place to place?
What causes them to become extinct? With few exceptions, germs migrate
for the same reason as man,--search for food, love of conquest, and
love of adventure. When there is plenty of food they multiply rapidly.
Full of life, overflowing with vitality, they move out for new worlds
to conquer. Like human beings, they will do their best to get away from
a country that provides a scanty food supply. Like men and women, they
starve if they cannot eat. Like boys and girls, they avoid enemies; the
weak give way to the strong, the slow to the swift, the devitalized to
the vitalized.

Human sociology imprisons, puts to death, deprives of opportunity to do
evil, or reforms those who murder, steal, or slander. Germ sociology
teaches us to do the same with injurious germs. We imprison them, we
take away their food supply, we kill them outright, or we starve them
slowly. They have a peculiar diet, being especially partial to
decomposing vegetable and animal matter and to what human beings call
dirt. By putting this diet out of their reach we make it impossible for
them to propagate their kind. By placing poison within their reach or
by forcing it upon them we can successfully eliminate them as enemies.
As the president of Mexico restored order "by setting a thief to catch
a thief," so modern science is setting germs to kill germs that harm
crops and human stock. Of utmost consequence is it that the body's germ
consumer--its pretorian guard--be always armed with vitality ready to
vanquish every intruding hostile germ. If we are false to our guard, it
will turn traitor and join invaders