urned area becomes the seat of a peculiar
overgrowth of fibrous tissue of the nature of keloid (p 401).

_Burns of Third Degree--Partial Destruction of the Skin._--The epidermis
and papillae are destroyed in patches, leaving hard, dry, and insensitive
sloughs of a yellow or black colour. The pain in these burns is
intense, but passes off during the first or second day, to return again,
however, when, about the end of a week, the sloughs separate and expose
the nerve filaments of the underlying skin. Granulations spring up to
fill the gap, and are rapidly covered by epithelium, derived partly from
the margins and partly from the remains of skin glands which have not
been completely destroyed. These latter appear on the surface of the
granulations as small bluish islets which gradually increase in size,
become of a greyish-white colour, and ultimately blend with one another
and with the edges. The resulting cicatrix may be slightly depressed,
but otherwise exhibits little tendency to contract and cause deformity.

_Burns of Fourth Degree--Total Destruction of the Skin._--These follow
the more prolonged action of any form of intense heat. Large, black, dry
eschars are formed, surrounded by a zone of intense congestion. Pain is
less severe, and is referred to the parts that have been burned to a
less degree. Infection is liable to occur and to lead to wide
destruction of the surrounding skin. The amount of granulation tissue
necessary to fill the gap is therefore great; and as the epithelial
covering can only be derived from the margins--the skin glands being
completely destroyed--the healing process is slow. The resulting scars
are irregular, deep and puckered, and show a great tendency to contract.
Keloid frequently develops in such cicatrices. When situated in the
region of the face, neck, or flexures of joints, much deformity and
impairment of function may result (Fig. 63).

[Illustration: FIG. 63.--Cicatricial Contraction following Severe Burn.]

In _burns of the fifth degree_ the lesion extends through the
subcutaneous tissue and involves the muscles; while in those of the
_sixth degree_ it passes still more deeply and implicates the bones.
These burns are comparatively limited in area, as they are usually
produced by prolonged contact with hot metal or caustics. Burns of the
fifth and sixth degrees are met with in epileptics or intoxicated
persons who fall into the fire. Large blood vessels, nerve-trunks,
joints,