en place at the base of the
sensitive laminae.]

When, for instance, the stain is not to be found in the superficial layers
of the sole, but is only discoverable by deep paring, then the injury is a
recent one.

Where the stain _is_ met with in the superficial layers of horn, and is
quickly pared out, then the injury has been inflicted some time before, and
has not been repeated. When, as is sometimes the case, layers of horn that
are stained are found alternated with layers that are healthy, then we have
evidence that the cause of the corn, whatever it may be, is not in constant
operation.

Similar indication of the age of the injury is also afforded by the colour
of the lesion.

A stain that is deep red is proof that the injury is comparatively recent.

A distinct yellow or greenish tinge, on the other hand, is evidence that
the injury is an old one.

_In the Moist Corn_ we have, in addition to the blood extravasation, the
outpouring of the inflammatory exudate. In the most superficial layer of
the horn this may not be noticeable. As one cuts deeper into the sole with
the knife, however, it will be found that the lower layers of horn are
more or less infiltrated with the discharge. This gives to the horn a soft
consistence, a yellow appearance, and a touch that is moist to the fingers.

With the accompanying inflammation the cells in the neighbourhood of the
injury are enfeebled and their normal functions interfered with. We may
thus expect a corresponding interference with the growth of horn. This is
exactly what happens, and as one cuts deeper still into the horn a point is
finally reached when a well-marked cavity is encountered. A pale yellow
and usually watery exudate fills it. This cavity points out the exact spot
where the force of the injury has been greatest, where death of certain
cells of the keratogenous membrane has resulted, and where the natural
formation of horn has for a time been suspended.

_In the Suppurating Corn_, as in moist corn, we have pathological changes
due to the tissue reaction to the injury, _plus_ the addition of pus
organisms. Confined within the horny box we have a discharge that, by
reason of the living and constantly multiplying elements it contains--the
pus organisms--is always increasing in bulk. This must be at the expense
of the softer structures of the foot. Accordingly, as the formation of pus
increases, we get pressure upon and final gangrene of the sensitive sole
a