is broken down, and the
suppurative process spreads. A fresh accession of leucocytes, however,
forms a new barrier, and eventually the spread is arrested, and the
collection of pus so hemmed in constitutes an _abscess_.

Owing to the swelling and condensation of the parts around, the pus thus
formed is under considerable pressure, and this causes it to burrow
along the lines of least resistance. In the case of a subcutaneous
abscess the pus usually works its way towards the surface, and "points,"
as it is called. Where it approaches the surface the skin becomes soft
and thin, and eventually sloughs, allowing the pus to escape.

An abscess forming in the deeper planes is prevented from pointing
directly to the surface by the firm fasciae and other fibrous structures.
The pus therefore tends to burrow along the line of the blood vessels
and in the connective-tissue septa, till it either finds a weak spot or
causes a portion of fascia to undergo necrosis and so reaches the
surface. Accordingly, many abscess cavities resulting from deep-seated
suppuration are of irregular shape, with pouches and loculi in various
directions--an arrangement which interferes with their successful
treatment by incision and drainage.

The relief of tension which follows the bursting of an abscess, the
removal of irritation by the escape of pus, and the casting off of
bacteria and toxins, allow the tissues once more to assert themselves,
and a process of repair sets in. The walls of the abscess fall in;
granulation tissue grows into the space and gradually fills it; and
later this is replaced by cicatricial tissue. As a result of the
subsequent contraction of the cicatricial tissue, the scar is usually
depressed below the level of the surrounding skin surface.

If an abscess is prevented from healing--for example, by the presence of
a foreign body or a piece of necrosed bone--a sinus results, and from it
pus escapes until the foreign body is removed.

#Clinical Features of an Acute Circumscribed Abscess.#--In the initial
stages the usual symptoms of inflammation are present. Increased
elevation of temperature, with or without a rigor, progressive
leucocytosis, and sweating, mark the transition between inflammation and
suppuration. An increasing leucocytosis is evidence that a suppurative
process is spreading.

The local symptoms vary with the seat of the abscess. When it is
situated superficially--for example, in the breast tissue--the af