ANATOMY AND PHYSIOLOGY OF THE HORSe’s FOOT. 727 
from -which they spring. On a horse about fifteen hands 
high, this surface was calculated to be about 212 square 
inches, or nearly one square foot and a half. Recent micro- 
scopic research, however, would tend to show that in reality 
this extension of surface is considerably understated, and that, 
by a -wonderful arrangement of the sides of the laminae, 
their superficies is immensely multiplied. 
In their minute structure, they are found to he composed of 
similar elements to the papillae or villi which w r e have just 
described. The basis or framework of each leaf is a thin, 
closely-woven mesh of white fibrous tissue, given off from 
the dermo-perioste. These fibres, which are in reality a con- 
tinuation of those covering the bone, evenly and compactly 
like a sock, are arranged in a somewhat definite manner to 
resist vertical strain, and offer but few elastic fibres among 
them, so far as I can perceive. Each leaf, examined with the 
microscope, would appear to be composed of two attenuated 
planes of white fibrous tissue, proceeding parallel to each 
other from the top to the bottom, and which serve to sustain 
the blood-vessels and nerves so freely distributed to it. They 
are all covered by the same fine membrane -which envelopes 
the villi of the coronary cushion, sole, and frog. This mem- 
brane, in the fresh state, is always thickly covered with soft 
epithelial cells, which cause the laminae to feel moist and 
greasy. 
The bed or 6i dermo-perioste” from which the laminae arise 
has been aptly named the “ reticulum processigerum” or leaf- 
supporter. It is rather thick, especially at the front and 
sides, and within its meshes is disposed a gorgeous network 
of blood-vessels, that proceed from the little apertures so 
numerous on the face of the bone, and of itself constitutes a 
conspicuous scarlet covering. 
From this vascular system a^number of arteries pass trans- 
versely to the fixed border of the lamina, where they run 
parallel with it from top to bottom, throwing off at intervals 
into the substance of the leaf numerous tiny branches, which 
again detach others from their sides. These ultimate rami- 
fications form loops with their collaterals in a wavy manner 
towards the free margin of the lamina, and this close, but 
exceedingly beautiful arrangement of arteries gives the leaves 
quite a fleshy appearance. 
I have always remarked that the inflammation in laminitis, 
in the great majority of cases, if not in every case, is most con- 
centrated around the front and lower portion of the vascular 
structures covering the os pedis, between the patilobe eminences 
on each side, and generally extends upwards to above the level 
