temporarily or chronically injured." The common conception
of a poison is any substance which, in small quantity, will destroy life,
except such as act by purely mechanical means, as, for example, powdered
glass.

Some substances that are not usually looked upon as poisons may destroy
life if given in large doses, such as common salt. Other substances which
are perfectly harmless when taken into the body in the usual way are
poisons if injected into the circulation, such as distilled water, milk, or
glycerin. Living organisms are not "chemical substances," and are not
considered in this connection.

SOURCES OF POISONING.

Poisoning may come from many causes, among the chief of which are the
following:

(1) _Errors in medication._--By using the wrong substance or too large dose
an animal may be poisoned.

(2) _The exposure of poisons used for horticultural, technical, or other
legitimate purposes._--Poisons used for spraying plants, disinfecting,
poisoning vermin, dipping cattle or sheep, painting, smelting, dyeing, or
other purposes may be so handled as to come within the reach of animals.

(3) _Damaged food._--Food that has undergone putrefaction or certain kinds
of fermentation or heating, may have become poisonous, producing forage
poisoning, meat poisoning, cheese poisoning, etc.

(4) _Poisonous plants in the pasture or forage._

(5) _The bite or sting of a poisonous insect or the bite of an animal._

(6) _Malicious poisoning._

THE ACTION OF POISONS.

The action of poisons may be either local, and exerted directly on the
tissues with which they come in contact, or remote, acting through the
circulation or the nervous system; or both local and remote action may be
exerted by the same drug. Poisons which act locally generally either
destroy by corrosion the tissues with which they come in contact or by
inhalation set up acute inflammation. When any corrosive agent is taken
into the stomach in poisonous quantities, a group of symptoms is developed
which is common to all. The tissues with which the agent comes in contact
are destroyed, sloughing and acute inflammation of the surrounding
structures take place; intense pain in the abdomen and death ensue. In a
like manner, but with less rapidity, the same result is reached if the
agent used be not of a sufficiently corrosive nature to destroy the
tissues, but sufficiently irritating to set up acute inflammation of the
mucous membrane of the digestive tr