STRUCTURE AND DISEASES OF THE HORSE’S FOOT. 361 
sure of the bones of the foot upon the broader surface of the hoof; and, 
lastly, this arrangement of an elastic cushion, increasing in thickness 
toward the posterior aspect of the foot, affords an elastic support to the 
movements of the coflin-bone in the hoof, thereby aiding the elastic 
lamine upon the superior convex surface in support of the bone. While 
the toe of the coffin-bone is comparatively stationary, there is consider- 
able motion of the heel upon the toe as a center, thereby contributing to 
the extent, freedom, and ease of movement of the foot. 
Molded upon the surface of the coffin-bone, over its entire extent, is 
a thick, villous, highly vascular, and sensitive membrane having the 
general name of the sensitive foot, besides having several local names 
derived from the part of the-hoof under which it lies, as sensitive lam- 
Me, sensitive sole, and sensitive frog. 
This tissue is derived mainly from the skin. It may be said to bea 
process from the skin, covering the coffin-bone, and altered in its struc- 
ture to adapt it to its office as an excretory membrane. It exactly cor- 
responds to that portion of the human skin which produces the nails. 
The preper skin of the leg, as it arrives at the foot, becomes thickened 
and altered in its structure, constituting the mass around the summit 
of the hoof, to which veterinary writers have given the name of coro- 
nary band. This is lodged ina groove seen around the upper edge of 
the horny wail, and from this the straight fibers of the wail are se- 
ereted. From the coronary band there is a prolongation of the skin 
downward over the coffin-bone. This tissue is thrown into permanent 
folds or lamine, the sensitive lamine, between five and six hundred in 
number, arranged lengthwise of the foot. _They secrete matter which 
enters into the formation of the horny wall, to the lamine of whieh they 
are very closely united. According to Virchow, each lamina corre- 
sponds to a single papilla, as seen on the surface of the skin. Similar 
tissue, thickly studded with secreting papille, covers the inferior sur- 
face of the coffin-bone, the fibro-elastic frog, and the widely distributed 
cartilages, already mentioned. This tissue is richly supplied with nerves 
and blood-vessels, the latter forming large plexuses which extend to 
and above the margin of the hoof. ' 
The elastic lamin are found around the whele convex surface of the 
coffin-bone, having a breadth of about one-tenth of an inch and a length 
of about two inches in front, decreasing to an inch at the heels. These 
laminz, much reduced in size and importance, are continued over the 
bars into the center of the foot. Each lamina consists of a single plait, 
or fold of two layers of membrane, which apply closely to, and are 
firmly attached to, two corresponding surfaces of the laminz of the horny 
hoof. Hither in the laminz themselves, or in the fibrous membrane on 
which they rest, and which is the medium of their union with the bone, 
great elasticity resides, so that the coffin-bone, with the weight it sus- 
tains, receives a large part of its support from the lamina, acting as 
hundreds of elastic springs. It is this structure and arrangemént that 
aid greatly in obviating shocks and preserving the integrity of the soft 
tissues at the bottom of the foot. By taking two strips of paper and 
folding them together in regular, even plaits, we have an illustration of 
the method of union between the soft and sensitive and the herny lam- 
ine. If, in addition, one of the layers be considered elastic, the philos- 
ophy of the elastic suspension of the foot would be obvious. 
The tissue constituting the sensitive sole, averaging perhaps one-oighth 
of an inch, thinner over the frog and thicker ever the heels, is even more 
fibrous, vascular, and sensitive than the lamine. Itis closely connected 
with the fibrous tissue of the sensitive lamine in front and the cover- 
