e bone. It presents the appearance of fine longitudinal streaks,
which, when closely examined with a needle, are found to consist of
numerous fine leaves. These extend downwards from the lower border of the
coronary cushion to the inferior margin of the os pedis. At this point each
terminates in several large villous prolongations, which extend into the
horny tubes at the circumference of the sole. At the point of the toe this
membrane sometimes shows a V-shaped depression, into which fits a inverted
V-shaped prominence on the inner surface of the wall at this point.

The sensitive laminae increase in width from above to below. Their free
margin is finely denticulated, while their sides are traversed from top to
bottom by several folds (about sixty), which, examined microscopically, are
seen to consist of secondary leaves, or _laminellae_.

Examined on the foot, deprived of its horny covering, the sensitive laminae
are, the majority of them, in close contact with each other. In the normal
state this is not so. The interstices between the leaves are then occupied
by the horny leaves, to be afterwards described as existing on the inner
surface of the wall.

Reaching and rounding the heels, the sensitive laminae extend forward for a
short distance, where they interleave with the horny laminae of the bars.

Much discussion has centred round the point as to whether or no the cells
of the sensitive laminae take any share in the formation of the horn of the
wall. This will be alluded to in a future chapter.

I. THE HOOF.

Removed from the foot by maceration a well-shaped hoof is cylindro-conical
in form, and appears to the ordinary observer to consist of a box or case
cast in one single piece of horn. Prolonged maceration, however, will show
that the apparently single piece is divisible into three. These are known
as (1) THE WALL, (2) THE SOLE, and (3) THE FROG. In addition to these, we
have also an appendage or circular continuation of the frog named (4) THE
PERIOPLE, or CORONARY FROG BAND. These various divisions we will study
separately.

1. THE WALL is that portion of the hoof seen in front and laterally when
the horse's foot is on the ground. Posteriorly, instead of being continued
round the heels to complete the circle, its extremities become suddenly
inflected downwards, forwards, and inwards. These inflections can only be
seen with the foot lifted from the floor, and form the so-called _Bars_. It
will be notice