362 AGRICULTURAL REPORT. 
ing of the heels and frog behind. From it the horny sole and frog are 
secreted. 
The sensitive tissues that invest the bones of the foot are covered and 
protected by a thick, dense, horny cap or box, the hoof. (Fig. 11.) 
The physiological relation of the hoof to the parts which it covers is 
essentially the same as that of the human nail to the parts covered by 
it. Functionally, its relations are more extensive and complete, and 
whatever differences exist in structure, in form, or extent of develop- 
ment, come from modifications for special use. 
The hoof consists of three portions, which are so closely united as to 
seem but one; yet, by maceration, or by boiling, they can be separated. 
These are the wall or crust, the sole, and the frog. 
The wall (Fig. 13,* e, e, e) is all that part of the hoof that is visible 
below the hair when the foot is placed upon the ground. It is in the 
form of a cylinder, cut across obliquely at the top. It is deepest in front, 
from three to four inches, and grows gradually less in depth toward 
its posterior aspect. This wall, which is secreted mainly by the 
coronary band, and partly by the sensitive wall beneath, isin front about 
half an inch in thickness, becoming thinner on the back side as it extends 
around the foot. It has an edge bearing upon the ground of about half 
an inch around the outside of the bottom of the foot. (Fig. 13, e, e.) 
Upon the inner side of the foot the wall is thinner than upon the out- 
side. 
' The wall is divided into toe, quarters, heels, and bars, superior or 
coronary border, inferior or solar border, and lamine. 
Passing any special description of the borders, the laminze deserve 
more particular attention. 
The lamina, or lamellee, (Fig. 12,) are the very numerous, narrow, and 
thin plates which cover the entire interior aspect of the horny wall. 
They are in length from two inches in front to less than an inch at the 
heels. They are also visible over the bars. They have a very constant 
width of about one-tenth of an inch, and extend from the lower to 
the upper border of the hoof, are essentially parallel to each other, and 
have a free edge and two free surfaces. Each lamella is received into 
and is very closely united to two of the lamelle of the sensitive wall. 
By this arrangement the surface by which the horny wall is attached to. 
the sensitive heof is very largely increased, (by exact calculation of Dr. 
Evans, increased by twelve times,) and this attachment, while possess- 
ing great strength, has great elasticity, and admits of considerable 
motion between the horny sole and the coffin-bone contained in it. 
The toe (Fig. 13, a) constitutes about two-thirds of the wall, and is 
sometimes subdivided, for minute description, into toe, inner toe, and 
outer toe, (Fig. 13, a, a, a.) It is the deepest and thickest part of the 
wall, and stands at an angle, in the average of good feet, of about forty- 
five degrees. When the angle of inclination is much greater than this, 
the feet are designated as flat and weak. Flat and weak feet usually 
obtain in large and heavy animals, and it has been thought that the 
foot is flattened, the anterior wall drawn down, by the weight. 
The quarters (Fig. 13, l', 0’) are the portions on each side, midway 
between the toe and the heels, and are designated as the inside and 
outside quarters. The fibers composing them run obliquely upward 
** Fra. 13.—Ground surface of hoof, from Miles: a, toe; a1, inner toe; a2, outer toe; 
»1, inner quarter; 62, outer quarter; ¢c1, inner heel; ¢2, outer heel; d, @, d, sole; ¢,é, 
wall of the hoof; jf, f, the bars; g, g, the commissures; h, k, l, the frog; hk, part under 
the navicnlar joint ; k, boundary of fhe cleft; i, ¢, the bulbs of the heels. 
