In the management of wounds and other diseased conditions the main
object of the surgeon is to promote the natural reparative process by
preventing or eliminating any factor by which it may be disturbed.

#Healing by Primary Union.#--The most favourable conditions for the
progress of the reparative process are to be found in a clean-cut wound
of the integument, which is uncomplicated by loss of tissue, by the
presence of foreign substances, or by infection with disease-producing
micro-organisms, and its edges are in contact. Such a wound in virtue of
the absence of infection is said to be _aseptic_, and under these
conditions healing takes place by what is called "primary union"--the
"healing by first intention" of the older writers.

#Granulation Tissue.#--The essential and invariable medium of repair in
all structures is an elementary form of new tissue known as _granulation
tissue_, which is produced in the damaged area in response to the
irritation caused by injury or disease. The vital reaction induced by
such irritation results in dilatation of the vessels of the part,
emigration of leucocytes, transudation of lymph, and certain
proliferative changes in the fixed tissue cells. These changes are
common to the processes of inflammation and repair; no hard-and-fast
line can be drawn between these processes, and the two may go on
together. It is, however, only when the proliferative changes have come
to predominate that the reparative process is effectively established by
the production of healthy granulation tissue.

_Formation of Granulation Tissue._--When a wound is made in the
integument under aseptic conditions, the passage of the knife through
the tissues is immediately followed by an oozing of blood, which soon