ANATOMY AND PHYSIOLOGY OF THE HORSE^S FOOT. 647 
to below, and instead of their remaining invariably the 
same we should have them more or less increased in breadth 
and thickness, and far from offering that regularity and 
parallellism which is so striking in a freshly separated hoof. 
Did the living leaves, indeed, pour out a corneous matter 
over the whole of their surface, and add this matter to the 
leaves on the inner face of the wall, we should have a 
deformed hoof, such as we are familiar with in serious cases 
of chronic laminitis, or one of a very different shape and 
character to the hoof we would select as a healthy and 
perfect specimen. 
In a normal state, then, the horny laminae are not formed 
by those springing from the os pedis, but are the joint pro- 
duction of the coronary zone and the keratogenous membrane 
covering the commencement of the latter ; from this circum- 
stance it is that the fibres of the crust and the leaves on its 
inner face constitute one continuous mass, which cannot by 
any process or means known to me be shown to offer any 
agglutination or simple apposition of texture, such as can 
be proved to exist between the sole and wall, periople and 
wall, or frog and sole. 
Under ordinary conditions, therefore, the podophyllae con- 
tribute but little towards the formation of the horn plates 
with which they interdigitate, and that only at their com- 
mencement, where they combine with the coronary cushion 
to complete the keratogenesis and lamellar configuration of the 
inner face of the wall. But, it may be asked, what are the 
ordinary functions of these highly organised podophylke, if they 
are not intended to secrete the laminae of the wall ? Surely 
their great vascularity was given them for some important end, 
and if not for the production of the hoof, what then ? The 
uses of the laminae are most important. At their origin, as we 
have just said, they aid in giving shape and material to the 
inner face of the crust; they likewise secrete over their 
entire surface a certain, though limited, quantity of horny 
matter in the shape of pulpy epidermic cells which lie 
between their enveloping membrane and the horny laminae. 
These pulpy cells not only protect this highly sensitive 
living surface by interposing themselves as a kind of cushion 
between it and the dense wall, but they likewise maintain 
the horny laminae and the wall itself to a certain depth 
moist and elastic long after these have left the coronary 
cushion, until, in fact, they have extended beyond the sole. 
The vascular laminae also, in addition to the functions 
enumerated, not only aid in attaching the hoof in the most 
intimate manner to the pedal bone, but by their peculiar 
