ATROPHY OF THE PLANTAR CUSHION. 
501 
or, if it is preferred, which is one of the first symptoms manifested 
of the contraction of the wall. 
The idea of looking at this contraction as a cause of corns is 
not new. Lafosse, Sr., had already remarked that dry corns 
may appear, without any apparent causes , on feet with strong 
heels, and for this reason he called them natural . M. Bouley 
prefers the name of essential , because, for him, these lesions are 
u inherent to some feet, as a consequence of their manifestation of 
their condition,” and he adds that “ they are principally seen in 
heavy, high, contracted or hoof-bound feet; or again, but acciden¬ 
tally, in those which, by want of wearing, an excessive length has 
been reached.” We believe that from an etiological point of view, 
corns ought to be divided into three categories, a first, for those in 
which the contraction of the wall exists, and we would call them 
symptomatic; a second, which we name essential , appearing in 
feet with high heels from neglect of shoeing; a third category, 
including the corns characterized by high inflammation, with 
suppuration or gangrene of the velvety tissue underneath the ex¬ 
treme end of the branches of the sole ; and corns exclusively found 
in flat feet with low heels, which in the majority of cases are 
due to the compression, by the shoe or a foreign substance, of the 
corresponding region of the sole, naturally too weak or rendered 
so by the shoer. 
Considered in the symptomatology and the prognosis, the var¬ 
ieties of corns differ. The symptomatic corn is always dry ; the 
essentia] corn may be dry or moist. The accidental corn is always 
suppurative. This last is the most serious ; if neglected it may be 
accompanied with separation of the wall. The symptomatic corn 
is subject to return. 
How explain the formation of the dry corn in case of con¬ 
traction of the wall ? If the action of the plantar cushion upon 
the velvety tissue underneath is harmless in the physiological 
condition, it cannot be so when that organ has lost, by its atrophy, 
its elasticity. There is then an abnormal pressure, producing a 
transudation through the walls of the blood vessels of the velvety 
tissue, blood which is mixed with the layers of horn as they are 
secreted. 
