270 
A. ZUNDEL. 
I. Divisions. —Lafosse Sr. lias distinguished them into 
natural and accidental, while Girard considers them all as acci¬ 
dental. H. Bouley designates as essential those which come from 
other than external causes. We believe that it would be better 
to establish the divisions on pathological and anatomical bases, 
and admit a corn of the wall, or laminated, that which has its 
seat in the laminae which unites the wall to the tissues under¬ 
neath, viz., in the keraphyllous and podophyllous tissues of the 
heels and bars, and a corn of the sole, or velvety, that which has 
its seat in the velvety tissue which unites the sole to the fleshy 
parts. The laminated corn corresponds exactly to the “ natural ” 
of Lafosse and to the “essential” of Bouley. It is due to lacera¬ 
tions in the movements of expansion of a badly made foot. The 
other is due to contusions. Whatever may be the adopted divi¬ 
sions, we, with Girard, and as admitted in practice, recognize in 
each category the dry, the moist and the suppurative corn. 
II. Etiology. —All feet are exposed, but not all predisposed to 
corns. They are more frequent in heavy feet, with those where 
the heels are high or contracted, in which there is a motion of re¬ 
traction of the hoof which interferes with the displacement back¬ 
ward of the third phalanx at the time of rest, and hence the 
lacerations are easy; besides, there is a continual pressure upon 
the living parts of the posterior region of the nail. Corns are 
frequently observed in excessively long feet, where the hoof does 
not receive the moisture necessary to its elasticity; it then loses 
its suppleness and fails to assist the internal motions of the parts 
contained within. It is seen whenever the hoof is too dry, the 
posterior diameter of the foot being then diminished. Corns are 
seen on weak feet, on which the hoof is too thin to resist the 
dilating effect of the internal structure, and spreads excessively. 
Wide and flat feet, with low heels, in which the inferior surface 
of the branches of the sole is on a level with the plantar border 
of the quarters and bars, are very often affected with corns. The 
pressure of the shoe, or the roughness of the ground produce 
these bruises through the sole. Here the conditions are unfavor¬ 
able to the normal dilatation of the hoof; the ungueal phalanx, 
being unsupported by the convexity of the sole, has a tendency 
