366 
ANATOMY OF THE HORSE. 
less than one inch. In breadth there is no variation : all measure 
alike—one-tenth of an inch. 
Organization. —The laminae are highly organized, though they 
are not equally so with the sensitive sole or sensitive frog; nor 
are they so red as those parts: and the obvious explanation 
of this is, that (over and above what is requisite for their own 
nutrition) all the blood they have occasion for is only that which 
is sufficient for the secretion of the horny laminae. 
The Sensitive Sole. 
The sensitive sole, or (as Sainbel calls it) the fleshy sole, is the 
fibro-vascular substance covering the arched concave, or ground 
surface of the coffin-bone : in fact, is the part corresponding to 
the horny sole. 
Structure. —The same kind of elastic fibrous structure that 
sustains the laminae is found constituting the groundwork of the 
sensitive sole; only that in the latter case it is closer, denser, 
and firmer in its texture. Upon this is spread a remarkably 
beautiful venous net-work. And the whole is enveloped in an 
outer cuticular covering, derived from the heels and frog, from 
which are sent villous processes, loaded with the points of arteries, 
into the porosities of the horny sole : not, however, perpendicularly 
downward, but in an oblique direction—downward and forward— 
the same in which the horny fibres grow. 
Connexion. —Around the circumference of the coffin-bone, the 
sensitive sole is connected with the fibrous substance descending 
from the wall, together with the tapering, vanishing points of 
the laminae. In the centre, it is united with the bars and frog. 
But its principal attachment consists in its being firmly rooted 
into the sole of the coffin-bone ; a connexion that receives con¬ 
siderable addition from the bloodvessels issuing out of the sub¬ 
stance of the bone. 
Thickness. —The sensitive sole varies in thickness at different 
places. On an average, it my be said to measure one-eighth of 
an inch in thickness. In the vicinity of the frog, it is something 
less than this. At the heels, it possesses double that thick¬ 
ness. 
Organization. —This is one of the most vascular and sensitive 
parts in the body. Independently of the much admired venous 
net-work expanded over the fibrous substance of the sole, arteries 
enter it issuing from the substance of the bone, and penetrate its 
villi, which, by taking this course, elude all compression and ob¬ 
struction : there are also others—the nutrient arteries ; but these 
have an external origin, from the inferior coronary artery. The 
chief assemblage of arteries takes place within the villi, upon the 
