THE HORSE’S FOOT. 
3 
The external parts of the foot are four in number; the wall, 
the sole, the frog and the periople. These form, together, a 
horny box, the nail, or hoof, which is adapted exactly by its in¬ 
ternal cavity to the external contour of the sub-horny mem¬ 
brane, contracting with it an intimate union by a reciprocal recep¬ 
tion, and thus completing the structure of the foot, furnishing to 
the sensitive parts an apparatus, thick, hard, resisting and at the 
same time elastic, which makes one with them, and protects them 
against violence from the substances with which the foot, from 
the nature of its function, must necessarily come in contact. The 
horny substance which constitutes the hoof h'as a fibrous aspect ; 
it is hollowed all over by cylindrical canals, whose superior ex¬ 
tremities, widened into a funnel shape, cover the papillae of the 
matrix of the hoof, either at the coronary band or velvety tissue, 
while the inferior opens in the wall upon the plantar border, in 
the sole and frog, at the external or inferior face. These canals 
are rectilinear, except those of the frog, which are flexuous; 
their diameter varies from 0, 02 to 0, 2 or 04 mm- These tubes are 
not only hollowed in the horny substance; they have also proper 
walls, of very great thickness, formed of numerous concentrical 
layers, received into each other. These are lamellae of pavimen- 
tous epithelium, which constitute the horny tissue; in the walls of 
the horny tubes, they are grouped flatwise around their inferior 
canals, and stratified from within outwards, so as to form success¬ 
ive and concentrical layers ; in the intertubular horn, these lamellae 
are not stratified in a direction parallel to that of the tubes, but 
at right angles with it. Around the tubes, the lamellae have an 
oblique intermediate direction. A granular opaque substance 
fills up the space lying between the horny tubes and the papillae. 
The hoof, which is a part of the epidermis, develops simi¬ 
larly, that is, by the constant formation of cells in the layer 
which corresponds to the mucous malpighian body, at the expense 
of the plasma thrown off by the numerous blood vessels of the ker- 
atogenous membrane. The velvety tissue is the starting point of 
the elements of the sole and frog; the perioplic band is the organ 
secreting the periople; and the coronary band proper, the matrix 
of the wall. Upon these different parts, the epithetial cells mill- 
