36 DISEASES OF THE HORSE’S FOOT 
os pedis and the plantar cushion. To the irregularities of 
the latter body—its bulbs, pyramidal body, and its lacune 
—it is closely adapted. Its surface may, therefore, be — 
divided into (a) The Sensitive Frog, and (b) The Sensitive 
Sole. 
(a) The Sensitive Frog is that part of the velvety tissue 
moulded on the lower surface of the plantar cushion. The 
shape of the plantar cushion has already been described as 
identical with that of the horny frog. It only remains to 
state that, like the coronary cushion, the surface of the 
sensitive frog is closely studded with papille. The cells 
clothing the papille are instrumental in forming the horny 
frog. 
(b) The Sensitive Sole—As its name indicates, this is 
the portion of the keratogenous membrane that covers the 
plantar surface of the os pedis. It also is clothed with 
papille, which again give rise to the formation of that part 
of the horny box to which they are adapted—namely, the 
sole. 
3. THe Popopnynious Tissuz, on Sensitive Lamina.— 
This portion of the keratogenous membrane is spread over 
the anterior face and sides of the os pedis, limited above by 
the coronary cushion, and below by the inferior edge of 
the bone. It presents the appearance of fine longitudinal 
streaks, which, when closely examined with a needle, are 
found to consist of numerous fine leaves. These extend 
downwards from the lower border of the coronary cushion 
to the inferior margin of the os pedis. At this point each 
terminates in several large villous prolongations, which 
extend into the horny tubes at the circumference of the 
‘sole. At the point of the toe this membrane sometimes 
shows a V-shaped depression, into which fits a A-shaped 
prominence on the inner surface of the wall at this point. 
The sensitive lamine increase in width from above to 
below. Their free margin is finely denticulated, while 
their sides are traversed from top to bottom by several 
folds (about sixty), which, examined microscopically, are 
seen to consist of secondary leavés, or laminelle. 
