428 ANATOMY AND PHYSIOLOGY OF THE HOUSE'S FOOT. 
middle of the plantar surface, at the termination of the middle 
lacuna, constitute what is known among hippotomists as the 
“ pyramidal” body. This prominent portion of the cushion 
corresponds to the lower surface of the navicular bone. The 
pyramidal body terminates in a point beyond the middle of 
the sole towards the toe. On the outer side of each of the 
branches is a space which isolates them from the bars of the 
wall. These spaces are named the “ lateral lacunae.” 
In its structure, the plantar cushion differs somewhat 
widely from that of the cartilages or coronary cushion. 
Essentially composed of a framework of white fibrous tissue, 
which, in certain situations, would appear to be continuous 
with that entering into the composition of the lateral car- 
tilages, its histological anatomy seems lately to have been 
rather misunderstood. We have spoken of an inferior and 
superior tunic or covering belonging to this elastic body ; but 
to facilitate description, it may be stated that this envelope is 
a strong, continuous membrane, composed of dense white 
fibrous or inelastic tissue, from the inner surface of which 
proceed planes of fibres whose direction is more or less hori- 
zontal, or oblique forwards and downwards. In fig. 3 this 
stratification is made apparent in the vertical section. Though 
more or less interlaced with each other, a careful dissection 
will show their general disposition in wide horizontal or 
oblique layers, each of which is a band of dense inelastic tissue, 
that sends branches to the layer immediately in front or 
behind it, and thus constitutes a close mesh, whose spaces 
are widest at the heels and least towards the apex of the 
cushion. These interspaces are occupied by a yellow mate- 
rial, whose colour is in striking contrast with the pearly 
white hue of the inelastic framework, and the resemblance of 
which to adipose tissue procured for the whole cushion the 
designation of “ fatty frog,” given to it by the older farriers 
and hippotomists. That this substance is fat was the general 
opinion, I understand, until the publication of Professor 
Bouley’s admirable treatise on the horse's foot. That gen- 
tleman discountenanced the popular belief as to its adipose 
constitution, and took some pains to demonstrate that each 
of the interspaces was occupied by a very delicate membrane, 
possessed of great elasticity, which was folded or rolled 
upon itself many times, and was continuous throughout the 
cushion. 
I regret very much that my careful examinations of this 
tissue do not corroborate the learned professor's description, 
as I cannot discover the existence of a special elastic mem- 
brane disposed as stated by him. On the contrary, these 
