728 ANATOMY AND PHYSIOLOGY OP THE HOUSE’S FOOT. 
of the preplantar groove. The inferior limit of this space 
corresponds to the external orifices of the descending canals, 
which emit the branches of the circumflex artery. 
ITair-like veins spread themselves over the interior of these 
leaves, in a similar series of graceful festoons, to carry away 
the impure blood to the gradually increasing trunks in the 
fibrous leaf-bed. Nerves also, the last twigs of those larger 
branches which pass down the limb to the foot, wander over 
the entire structure of each lamina to confer sensibility. 
From the fundamental elements of the laminae being com- 
posed of inelastic fibres, and these but continuations of those 
forming the covering of the os pedis, they possess in reality 
but little elasticity, and that chiefly in a vertical direction. 
Their firmness and tenacity is very great. 
The membranous, vascular, nervous, and fibrous struc- 
tures we have described as composing the laminae, are not 
devoted solely to the formation of only a series of leaves, 
each with a thick base, gently thinning to a somewhat sharp, 
free border, and smooth lateral surfaces. Such has been 
the descriptions given in all the treatises on the anatomy 
of the horses’ foot, published up to the present time, I believe. 
In 1858, however, while engaged in a course of microscopical 
examinations of the structures entering into the composition 
of this organ, I observed, for the first time, a very wonderful 
arrangement of lateral laminae, or leaflets (which I have 
designated (i lamellce ”) on the sides of every leaf. These 
lamellae run from top to bottom of each lamina, are extremely 
delicate and very numerous, incline slightly forwards, and 
appear to be given off from the lamina in single fibres ; 
though 1 am inclined to think this is an illusion, and believe 
each lamella to be in reality in itself a secondary lamina, 
formed on the side of the primary one, just as the latter is 
derived from the dermo-perioste of the bone. They are of 
extreme tenuity, — so fine, indeed, that I have not been able 
to make out their structure satisfactorily, though they may 
be assumed to be only a miniature copy of the parent leaf, 
invested with basement membrane. 
If w r e make a fine transverse section of one of the laminae, 
and then view it with a high magnifying pow r er, we will 
find that these lamellae give it a plumose or fern-like appear- 
ance — the secondary series of leaflets standing out from its 
sides, something like the barbules or featherlets of a quill. 
Their relations to each other, and to the lamina, remind 
one very much of the gill of the eel, with its branchial 
lamellae. 
When speaking of the horny laminae and lamellae, with 
