ANATOMY AND PHYSIOLOGY OF THE HOUSERS FOOT. 247 
The figure of the hoof is generally conical, the wall smooth, 
regular, and rectilinear from above to below; if its under 
portion or base be examined, it will be found that its outline 
is more or less circular (not oval, as is frequently asserted), 
for a line which measures its length from toe to heel will he 
about equal to its width across the quarters ; it may be even 
less. It is curious to note, as pointed out by Professor 
Brambilla,* of Milan, that the half of this line is equal to 
the height of the hoof, and that the contour of the latter, 
viewed from the face of the wall, and seen in profile, are in- 
cluded in a semicircle, whose ray is also the height of the hoof. 
The plantar face of a well-formed, unshod hoof belonging to 
an unbroken horse, presents, then, a perfectly circular out- 
line, the centre of which is to be found at the crossing of 
the two diameters — antero-posterior and transversal — a 
little behind the point of the frog. It is also somewhat 
remarkable that the unit of measurement which divides the 
contour of the wall into equal portions, and exactly defines 
its conventional divisions into toe, mammillae, quarters, &c., 
is a thirteenth part of the circumference. The thirteenths are 
thus allotted : 
1 for each branch of the frog . . .2 
1 for each heel 2 
3 for each quarter ... . . .6 
1 for each mammilla 2 
1 for the toe 1 
Total . . 13 
The unit of measurement is found in the thickness of 
the heels taken from the re-entering angle at the ex- 
tremity of the sole, to the point of the heel — in reality, the 
width of one of the branches of the frog at its com- 
mencement. The length of each bar has also been found 
to correspond to one thirteenth of the contour of the wall, 
and therefore to the breadth of each branch of the frog at its 
base. So that if the frog was altogether removed, and the 
bars straightened out, they would replace it in completing 
the circumference of the parietal cone, leaving no interrup- 
tion at the posterior part of the wall. 
The whole of the circular border of the foot rests on the 
same plane, and consequently is everywhere in contact with 
the ground, to which it presents three qualities of horn, whose 
principal difference consists in their resistance. The first is 
the plantar border of the wall, hard, rigid, and narrow, com- 
posed, as it is, of the ends of the dense wall-fibres, which, 
* ‘ Theories Sur les Defauts du Pied.’ Milan, 1870. 
