The destruction of bacteria by means of heat and antiseptics is the
essence of modern surgery. It is, then, by preventing access of these
parasitic plants to the human organism (aseptic surgery), or the
destruction of them by chemical agents and heat (antiseptic surgery),
that we are enabled to invade by operative attack regions of the body
which a few years ago were sacred.

When the disease-producing bacteria gain access to the tissues and
blood of human and other animals by means of wounds, or through an
inflamed pulmonary or alimentary mucous membrane, they produce
pathological effects, provided there is not sufficient resistance and
health power in the animal's tissues to antagonize successfully the
deleterious influence of the invading parasitic fungus. It is the
rapid multiplication of the germs which furnishes a _continuous_
irritation that enables them to have such a disastrous effect upon the
tissues of the animal. If the tissues had only the original dose of
microbes to deal with, the warfare between health and disease would be
less uncertain in outcome. Victory would usually be on the side of the
tissues and health. The immediate cause of the pathogenic influence is
probably the chemical excretions which are given out by these
microscopic organisms. All plants and animals require a certain number
of substances to be taken into their organisms for preservation of
their vital activities. After these substances have been utilized
there occurs a sort of excretion of other chemical products. It is
probably the excretions of many millions of micro-organisms,
circulating in the blood, which give rise to the disease
characteristic of the fungus with which the animal has been infected.
The condition called sapræmia, or septic intoxication, for example, is
undoubtedly due to the entrance of the excretory products of
putrefaction bacteria into the circulation. This can be proved by