774 ANATOMY AND PHYSIOLOGY OF THE HORSe’s FOOT. 
It has also been observed that when the vascular laminae 
have been entirely destroyed and the surface of the pedal bone 
laid bare, and even injured, horn has been exuded on its sur- 
face. And, according to Professor Gourdon, we may remove 
the sole of the hoof, destroy the plantar cushion and plantar 
aponeurosis, and expose the pedal and navicular bones ; but 
no sooner has the wound been partially covered with granu- 
lations than horny matter begins to show itself on the 
surface and forms a sufficient protection, gradually extending, 
as it does, from the circumference to the centre until the 
whole is completely covered. Even the total destruction of 
the coronary cushion does not prevent the regeneration of 
horn at the part which this body occupied. 
The production of this horn might, with apparent reason, 
be attributed to the antecedent reconstitution of the kerato- 
genous membrane ; but observation demonstrates that it is 
not so : the subcorneous tissues, once destroyed, are not 
regenerated, or at least those which subsequently appear are 
so different to them that they scarcely bear any analogy. For 
instance, if, after the lamellated tissue of the os pedis has 
been removed, we examine that which has been developed 
in its stead, it will be found that there are no longer any of 
the characteristic leaves, and’ that the reticulated tissue be- 
neath has also disappeared ; all that is present is a thin 
indurated membrane intimately united to the surface of the 
hone, and covered with horny material that adheres very 
slightly to it, and is readily removed. 
The villous portion of the plantar surface is restored in a 
similar manner, being replaced by a uniformly smooth mem- 
brane composed of a hardened tissue, and destitute of the 
villi which form so remarkable a feature on the surface of 
the original membrane ; and the horn that exudes from it 
has not the usual aspect of that substance, but is thinner, 
softer, yellowish in colour, and so scanty in amount as to 
afford but a feeble protection to the living parts beneath. It 
is the same with the coronary cushion ; when some part of this 
is destroyed, the section of wall secreted does not assume its 
regular form, and there always remains an apparent depres- 
sion, while the living tissue is thin and hard, and in no 
respect like that which it has replaced. 
Gourdon states that the villi which have been, with the 
coronary cushion, destroyed, are reconstituted again on the 
foot existed in its place.” At the commencement of December, 1870, he is 
described as having “ four perfect new feet, is not shod with leather, goes 
better than he did before the attack of inflammation, and is hunted two days 
a week.” 
