a pink fringe around the periphery; when repair has taken place the
newly formed vessels disappear.

The exudate from the blood vessels in various ways assists in repair.
An injurious substance in the tissue may be so diluted by the fluid
that its action is minimized. A small crystal of salt is irritating to
the eye, but a much greater amount of the same substance in dilute
solution causes no irritation. The poisonous substances produced by
bacteria are diluted and washed away from the part by the exudate. Not
only is there a greater amount of tissue fluid in the inflamed part,
but the circulation of this is also increased, as is shown by
comparing the outflow in the lymphatic vessels with the normal. The
fluid exudate which has come from the blood and differs but slightly
from the blood fluid exerts not only the purely physical action of
removing and diluting injurious substances, but in many cases has a
remarkable power, exercised particularly on bacterial poisons, of
neutralizing poisons or so changing their character that they cease to
be injurious.

We have learned, chiefly from the work of Metschnikoff, that those
white corpuscles or leucocytes which migrate from the vessels in the
greatest numbers have marked phagocytic properties, that is, they can
devour other living things and thus destroy them just as do the
amoebæ. In inflammations produced by bacteria there is a very active
migration of these cells from the vessels; they accumulate in the
tissue and devour the bacteria. They may be present in such masses as
to form a dense wall around the bacteria, thus acting as a physical
bar to their further extension. The other form of amoeboid cell, which
Metschnikoff calls the macrophage, has more feeble phagocytic action
towards bacteria, and these are rarely found enclosed within them. It