ss may go, however, and its effects on the part implicated and on
the system as a whole, vary with different irritants and with the
intensity and duration of their action. A mechanical, a thermal, or a
chemical irritant, acting alone, induces a degree of reaction directly
proportionate to its physical properties, and so long as it does not
completely destroy the vitality of the part involved, the changes in the
tissues are chiefly directed towards repairing the damage done to the
part, and the inflammatory reaction is not only compatible with the
occurrence of ideal repair, but may be looked upon as an integral step
in the reparative process.

The irritation caused by infection with bacteria, on the other hand, is
cumulative, as the organisms not only multiply in the tissues, but in
addition produce chemical poisons (toxins) which aggravate the
irritative effects. The resulting reaction is correspondingly
progressive, and has as its primary object the expulsion of the irritant
and the limitation of its action. If the natural protective effort is
successful, the resulting tissue changes subserve the process of repair,
but if the bacteria gain the upper hand in the struggle, the
inflammatory reaction becomes more intense, certain of the tissue
elements succumb, and the process for the time being is a destructive
one. During the stage of bacterial inflammation, reparative processes
are in abeyance, and it is only after the inflammation has been allayed,
either by natural means or by the aid of the surgeon, that repair takes
place.

In applying the antiseptic principle to the treatment of wounds, our
main object is to exclude or to eliminate the bacterial factor, and so
to prevent the inflammatory reaction going beyond the stage in which it
is protective, and just in proportion as we succeed in attaining this
object, do we favour the occurrence of ideal repair.

#Sequence of Changes in Bacterial Inflammation.#--As the form of
inflammation with which we are most concerned is that due to the action
of bacteria, in describing the process by which the protective influence
of the inflammatory reaction is brought into play, we shall assume the
presence of a bacterial irritant.

The introduction of a colony of micro-organisms is quickly followed by
an accumulation of wandering cells, and proliferation of
connective-tissue cells in the tissues at the site of infection. The
various cells are attracted to the bacteria by a peculi