500 
A. LI AUT A Kb. 
quite rare, are due to causes imperfectly understood and probably 
of the same order as those producing toe cracks. They appear 
suddenly, and involve the wall in its whole thickness and extent. 
They follow the directions of the fibres of the wall, are rectilinear. 
Symptomatic quarter crack is a consequence of the contraction 
of the wall; it is formed more slowly than the accidental quarter 
crack, is seldom complete, and in the majority of cases seldom 
extends beyond the two superior thirds of the wall. It is more 
common on the internal than on the external quarter, a rational 
fact, since the contraction is often unilateral, and in this case it is 
the internal quarter which is abnormally altered. When the 
contraction is double, the internal quarter is more contracted than 
the external. 
The symptomatic quarter crack is seldom straight; though it 
nearly follows the general direction of the fibres, it is always more 
or less irregular and flexuous, either in the direction of the thick¬ 
ness or length of the wall. Almost always deep at its origin, it 
has a tendency to become superficial as it extends beyond the 
coronary band. Such are its most common and general symp¬ 
toms. Let us add also that it is prone to return. Why is it 
a symptom of the contraction of the wall, and therefore a conse¬ 
quence of the atrophy of the plantar cushion ? Immutable in the 
regions adherent to the os pedis, carried in its posterior parts by 
the motions of the fibro-elastie apparatus, the wall in the level of 
the posterior regions of the bone operates a sudden deviation from 
outwards inwards. It is that motion which renders the symp¬ 
tomatic quarter crack more or less irregular and sinuous; unless 
to the permanent actions of the motion of contraction is added 
that of one of the causes which give rise to the accidental quarter 
crack, in which case the lesion follows the direction of the fibres. 
The etiology of the variety of quarter crack that we call sym- 
tomatic, was not unknown to Lafosse, who said : “ When the 
quarter contracts, the hoof breaks in its lateral part.” 
2 . Sy7nptomatic Corn *—We call symptomatic corn the vari¬ 
ety which is the consequence of the atrophy of the plantar cushion, 
* Bleirne of the French. 
