_ bed-sore begins as a dusky reddish purple patch, which
gradually becomes darker till it is almost black. The parts around are
oedematous, and a blister may form. This bursts and exposes the papillae
of the skin, which are of a greenish hue. A tough greyish-black slough
forms, and is slowly separated. It is not uncommon for the gangrenous
area to continue to spread both in width and in depth till it reaches
the periosteum or bone. Bed-sores over the sacrum sometimes implicate
the vertebral canal and lead to spinal meningitis, which usually proves
fatal.

In old and debilitated patients the septic absorption taking place from
a bed-sore often proves a serious complication of other surgical
conditions. From this cause, for example, old people may succumb during
the treatment of a fractured thigh.

The granulating surface left on the separation of the slough tends to
heal comparatively rapidly.

_Prevention of Bed-sores._--The first essential in the prevention of
bed-sores is the regular changing of the patient's position, so that no
one part of the body is continuously pressed upon for any length of
time. Ring-pads of wool, air-cushions, or water-beds are necessary to
remove pressure from prominent parts. Absolute dryness of the skin is
all-important. At least once a day, the sacrum, buttocks,
shoulder-blades, heels, elbows, malleoli, or other parts exposed to
pressure, must be sponged with soap and water, thoroughly dried, and
then rubbed with methylated spirit, which is allowed to dry on the skin.
Dusting the part with boracic acid powder not only keeps it dry, but
prevents the development of bacteria in the skin secretions.

In operation cases, care must be taken that irritating chemicals used to
purify the skin do not collect under the patient and remain in contact
with the skin of the sacrum and buttocks during the time he is on the
operating-table. There is reason to believe that the so-called
"post-operation bed-sore" may be due to such causes. A similar result
has been known to follow soiling of the sheets by the escape of a
turpentine enema.

_Treatment._--Once a bed-sore has formed, every effort must be made to
prevent its spread. Alcohol is used to cleanse the broken surface, and
dry absorbent dressings are applied and frequently changed. It is
sometimes found necessary to employ moist or oily substances, such as
boracic poultices, eucalyptus ointment, or balsam of Peru, to facilitate
the separation of s