ANATOMY AND PHYSIOLOGY OF THE HORSE’S FOOT. 645 
It is formed in horizontal strata instead of vertical fibres, as 
in the normal wall ; it reaches only a limited thickness, and 
is dry, brittle, and readily removed in scales, no matter what 
length of time may have elapsed. 
Such appears to be the result when, from some cause 
or other, the podophyllae are suddenly deprived of their 
ordinary covering, and they are, as it were, placed at a dis- 
advantage and under pathological conditions, during which, 
for their own preservation, they assume an inordinate activity. 
This is well illustrated in the following experiment : — Ex- 
cise a portion of the wall from bottom to top, and divide the 
coronary cushion from the vascular lamina? by making a 
transverse incision in the direction of the coronary zone ; 
into this incision insert a band of lead, so as to mechanically 
separate the two, and thus prevent their corneous exudation 
from becoming fused in one mass. In the course of time a 
double wall will be formed, the cushion throwing out a 
thick mass that grows downward, above another mass 
developed from the laminae, both of which remain inde- 
pendent of each other. In this way we produce artificially 
what is a somewhat frequent result of disease, and which is 
vulgarly known among farriers and grooms as “ seedy hoof.” 
But in these experiments, and in these abnormal condi- 
tions, do we really discover the function of the podophyllae 
during health ? and can we satisfy ourselves that they in 
reality form any portion of the wall or the horny laminae with 
which they are so intimately and firmly inter digitated ? I 
think not; for careful microscopical investigation, and the 
most attentive anatomical and physiological study, go far 
to demonstrate that these circumstances are exceptional, and 
give rise to a corresponding exceptional energy in the for- 
mative powers of these vascular leaves for their own protec- 
tion ; and also that their share in the production of the wall 
may be said to be nil, while the part they take in the constitu- 
tion of the horny laminae is a comparatively unimportant one. 
When a portion of the wall is cut away as deep as the 
vascular laminae, but without denuding these, and leaving 
the horny laminae attached to them, we do not find a new 
wall reconstituted from this surface, or the slightest addition 
made to the thin pellicle of horn remaining. And if in an 
ordinary hoof we measure the thickness of the wall at the 
commencement of the keraphyllae and at their lower ends 
no difference will be found in it ; whereas if an addition to 
its substance was being constantly made by the vascular 
laminae, we should have it gradually increasing in volume 
from its upper to its lower border, at the same time the 
