bluish-brown colour; the epidermis gradually thins and gives way,
revealing the softened portion of catgut, which can be pulled out in
pieces, after which the wound rapidly heals and resumes a normal
appearance.


REPAIR IN INDIVIDUAL TISSUES

_Skin and Connective Tissue._--The mode of regeneration of these tissues
under aseptic conditions has already been described as the type of ideal
repair. In highly vascular parts, such as the face, the reparative
process goes on with great rapidity, and even extensive wounds may be
firmly united in from three to five days. Where the anastomosis is less
free the process is more prolonged. The more highly organised elements
of the skin, such as the hair follicles, the sweat and sebaceous glands,
are imperfectly reproduced; hence the scar remains smooth, dry, and
hairless.

_Epithelium._--Epithelium is only reproduced from pre-existing
epithelium, and, as a rule, from one of a similar type, although
metaplastic transformation of cells of one kind of epithelium into
another kind can take place. Thus a granulating surface may be covered
entirely by the ingrowing of the cutaneous epithelium from the margins;
or islets, originating in surviving cells of sebaceous glands or sweat
glands, or of hair follicles, may spring up in the centre of the raw
area. Such islets may also be due to the accidental transference of
loose epithelial cells from the edges. Even the fluid from a blister, in
virtue of the isolated cells of the rete Malpighii which it contains, is
capable of starting epithelial growth on a granulating surface. Hairs
and nails may be completely regenerated if a sufficient amount of the