e shoe too
wide, and too great a bearing thus given to the sole, then we get, first,
an undue pressure upon the last-named portion of the foot a bruise, and,
finally, lameness. The correct bearing should take in the whole of the wall
and the whole of the white line, and should _just impinge_ upon the sole.
Above all, the heels of the shoe should be of full length, otherwise, if
the shoe is worn just a little too long, its heels are carried under the
sole of the foot, and by pressure there produce a corn.

If, with these precautions in shoeing flat-foot, tenderness still persists,
a sole of leather or gutta-percha must be used with the shoe.

D. PUMICED-FOOT, DROPPED SOLE, OR CONVEX SOLE.

_Definition_.--This term is applied to the foot when the shape of the sole
is comparable to the bottom of a saucer. When least marked it is really an
aggravated form of flat-foot.

_Symptoms_.--In pumiced-foot the sole projects beyond the level of the
wall. The obliquity of the latter is more marked than in the previous
condition, and progression, to a large extent, takes place upon the heels.
In addition to its deformity, the horn is greatly altered in quality, and,
as the name 'pumice' indicates, is more or less porous in appearance,
bulging, and brittle.

_Causes_.--As a general rule, it may be taken that pumiced-foot is a sequel
of previous disease, although in its least pronounced form it may occur as
the result of accidental or other causes, such as those described in the
causation of flat-foot.

Occurring in its most marked form, there is no gainsaying the fact that
pumiced-foot is a sequel of either acute or subacute laminitis. As we shall
see when we come to study that disease, the dropping of the sole is brought
about by distinct and easily-understood morbid processes affecting the
sensitive structures. Briefly, these morbid processes in laminitis may be
described thus: The accumulated inflammatory exudate, and in some cases
pus, weakens and destroys the union between the sensitive and insensitive
laminae. This separation, for reasons afterwards to be explained, is
greatest in the region of the toe. The os pedis, loosened from its intimate
attachment with the horny box, is dropped upon the sole, and the sole,
unable to bear the weight, commences to bulge below.

The altered character of the horn is accounted for by the inflammatory
changes in the sensitive laminae and the papillae of the keratogenous
membrane general