me principle.

[Illustration: FIG. 6.--Passive Hyperaemia of Hand and Forearm induced by
Bier's Bandage.]

While these and similar methods have long been employed in the treatment
of inflammatory conditions, it is only within comparatively recent years
that their mode of action has been properly understood, and to August
Bier belongs the credit of having put the treatment of inflammation on a
scientific and rational basis. Recognising the "beneficent intention" of
the inflammatory reaction, and the protective action of the leucocytosis
which accompanies the hyperaemic stages of the process, Bier was led to
study the effects of increasing the hyperaemia by artificial means. As a
result of his observations, he has formulated a method of treatment
which consists in inducing an artificial hyperaemia in the inflamed area,
either by obstructing the venous return from the part (_passive
hyperaemia_), or by stimulating the arterial flow through it (_active
hyperaemia_).

_Bier's Constricting Bandage._--To induce a _passive hyperaemia_ in a
limb, an elastic bandage is applied some distance above the inflamed
area sufficiently tightly to obstruct the venous return from the distal
parts without arresting in any way the inflow of arterial blood (Fig. 6).
If the constricting band is correctly applied, the parts beyond
become swollen and oedematous, and assume a bluish-red hue, but they
retain their normal temperature, the pulse is unchanged, and there is no
pain. If the part becomes blue, cold, or painful, or if any existing
pain is increased, the band has been applied too tightly. The hyperaemia
is kept up from twenty to twenty-two hours out of the twenty-four, and
in the intervals the limb is elevated to get rid of the oedema and to
empty it of impure blood, and so make room for a fresh supply of healthy
blood when the bandage is re-applied. As the inflammation subsides, the
period during which the band is kept on each day is diminished; but the
treatment should be continued for some days after all signs of
inflammation have subsided.

This method of treating acute inflammatory conditions necessitates
close supervision until the correct degree of tightness of the band has
been determined.

[Illustration: FIG. 7.--Passive Hyperaemia of Finger induced by Klapp's
Suction Bell.]

_Klapp's Suction Bells._--In inflammatory conditions to which the
constricting band cannot be applied, as for example an acute mastitis, a
bubo in th