arsenic, and mercury,
which are well-known poisons. There are also many vegetable products,
not bacterial, which are poisonous in their nature, that is,
distributing to the blood and lymphatics certain substances in solution
which act on the cells of the various organs of the body in such a way
that the activity of those organs is stopped. Opium, cocaine, alcohol,
and some of the coal-tar products used for headaches, as phenacetin, are
deadly poisons when a limited dose is exceeded.

There are also certain poisons engendered in the body itself whose
action is similar to that of chemical bodies and which can hardly be
called bacterial. These poisons represent generally stages in the
process of nutrition where for some reason the normal process is
arrested and chemical bi-products are set free. Also, tissue which has
been thrown off, in or by any organ, begins to decompose, thereby
sending throughout the system the poisons of decomposition. Inflammation
too generally results in the breaking down of the cells and the
distribution of the resulting poisons. Of late years, much has been said
of the poisonous property of the body waste not disposed of by
excretion, and the theory of auto-intoxication, so-called, has received
many adherents. The great scientist, Metchnikoff, has even gravely
contended that it would be well for children to have their larger
intestine removed entirely, because in that organ putrefaction occurs,
the cause of the auto-intoxication he would try to prevent.

_External causes._

The external causes responsible for disease are due to conditions of
weather so severe as to be outside the possibility of self-protection.
Excessive heat is responsible each year for deaths from sunstroke, and
other conditions of weather are often the direct causes of disease, if
not of death.

Accidents are the indirect cause of death, and there will always be a
small proportion of the deaths occurring each year due to violence or
accident. But, inasmuch as these deaths are clearly preventable, it is
the duty of those interested in rural hygiene to study the reasons for
accidental death, and, if the number of such accidents can be reduced,
to strive for that reduction. As an example, it may be mentioned that
each year a number of deaths in New York State, and probably in other
states, occur from accidents at culverts and bridges, due to
insufficient protection in the way of railings and fences. A method of
reducing the