and on exposed parts this may prove a source of
disappointment after operations such as those for goitre or tuberculous
glands in the neck. There is sometimes considerable improvement from
exposure to the X-rays.

_Keloid._--This term is applied to an overgrowth of scar tissue which
extends beyond the area of the original wound, and the name is derived
from the fact that this extension occurs in the form of radiating
processes, suggesting the claws of a crab. It is essentially a fibroma
or new growth of fibrous tissue, which commences in relation to the
walls of the smaller blood vessels; the bundles of fibrous tissue are
for the most part parallel with the surface, and the epidermis is
tightly stretched over them. It is more frequent in the negro and in
those who are, or have been, the subjects of tuberculous disease.

[Illustration: FIG. 106.--Recurrent Keloid in scar left by operation for
tuberculous glands in a girl aet. 7.]

Keloid may attack scars of any kind, such as those resulting from
leech-bites, acne pustules, boils or blisters; those resulting from
operation or accidental wounds; and the scars resulting from burns,
especially when situated over the sternum, appear to be specially
liable. The scar becomes more and more conspicuous, is elevated above
the surface, of a pinkish or brownish-pink pink colour, and sends out
irregular prolongations around its margins. The patient may complain of
itching and burning, and of great sensitiveness of the scar, even to
contact with the clothing.

There is a natural hesitation to excise keloid because of the fear of
its returning in the new scar. The application of radium is, so far as
we know, the only means of preventing such return. The irritation
associated with keloid may be relieved by the application of salicylic
collodion or of salicylic and creosote plaster.

_Epithelioma_ is liable to attack scars in old people, especially those
which result from burns sustained early in childhood and have never
really healed. From the absence of lymphatics in scar tissue, the
disease does not spread to the glands until it has invaded the tissues
outside the scar; the prognosis is therefore better than in epithelioma
in general. It should be excised widely; in the lower extremity when
there is also extensive destruction of tissue from an antecedent chronic
ulcer or osteomyelitis, it may be better to amputate the limb.

AFFECTION OF THE NAILS

_Injuries._--When a nail