_polymorpho-nuclear leucocytes_, which have wandered from the vessels,
are also present in the spaces. These act as phagocytes, their function
being to remove the red corpuscles and fibrin of the original clot, and
this performed, they either pass back into the circulation in virtue of
their amœboid movement, or are themselves eaten up by the growing
fibroblasts. Beyond this phagocytic action, they do not appear to play
any direct part in the reparative process. These young capillary loops,
with their supporting cells and fluids, constitute granulation tissue,
which is usually fully formed in from three to five days, after which it
begins to be replaced by cicatricial or scar tissue.

_Formation of Cicatricial Tissue._--The transformation of this temporary
granulation tissue into scar tissue is effected by the fibroblasts,
which become elongated and spindle-shaped, and produce in and around
them a fine fibrillated material which gradually increases in quantity
till it replaces the cell protoplasm. In this way white fibrous tissue
is formed, the cells of which are arranged in parallel lines and
eventually become grouped in bundles, constituting fully formed white
fibrous tissue. In its growth it gradually obliterates the capillaries,
until at the end of two, three, or four weeks both vessels and cells
have almost entirely disappeared, and the original wound is occupied by
cicatricial tissue. In course of time this tissue becomes consolidated,
and the cicatrix undergoes a certain amount of contraction--_cicatricial
contraction_.

_Healing of Epidermis._--While these changes are taking place in the
deeper parts of the wound, the surface is being covered over by
_epidermis_ growing in from the margins. Within twelve hours the cells
of the rete Malpighii close to the cut edge begin to sprout on to the
surface of the wound, and by their proliferation gradually cover the