272 
A. ZUNDEL. 
lateral contraction of the foot, and gives rise to corns. In this 
case the shoe resists the play of the horny box, and by itself, 
through the sole, exercises a great pressure upon the tissues 
underneath. Too high caulks, in preventing the resting on the 
frog, cause an excessive pressure on the inside of the foot, and 
compel it to rest on the heels and the branches of the sole, which 
are too much lowered. The opposite excess, when the shoe is 
thin at the heels, as in the Coleman shoe—when it is thick at the 
toe and thin at the heels—produces a similar result, because in 
increasing the pressure on the heels, it gives rise to bruises of the 
tissues through the retrossal processes, which come down too 
heavily. A very wide shoe, too thin, may also contribute to the 
genesis of corns, because then, the shoe helping, with the inten¬ 
sity of the reactions on the pavement or on too hard and stony 
roads, the shoe soon gives under the foot, and compresses the sole 
and tissues beneath. 
The manner in which the shoe is put on may also be a cause of 
corns ; the shoe ought to rest exclusively on the inferior border 
of the wall, and not touch the sole ; when it is too narrow it may 
be a cause of contusion or of contraction ; if too wide it prevents 
the natural expansion. It is upon horses long shod that the 
wrong application of the shoe as a cause of corns is observed. 
As a consequence of the growth of the hoof, the shoe no longer 
sufficiently protects the plantar border of the foot, the heels of 
the shoe being inward and pressing on the branches of the sole > 
this is especially the case when the shoe is thinned by wearing; 
it yields, and easily bruises the parts of the sole on which it 
rests ; high caulks, on a branch already too short, or too thin, act 
the more injuriously in this way, because, not being concentrated 
on the projection of the caulk, the branch gives way sooner, and 
presses still more on the heels. 
The shoe becomes an indirect cause of corns, when hard sub¬ 
stances, as stones or dry earth, are found between its superior and 
inferior face on the sole, or between the frog and the internal 
border of the branches of the shoe; this is a secondary cause, 
which was formerly considered of great importance. 
The work of horses lias a great influence; corns being very 
