FARMERS' l^fSTITUTES. 237 



the blood vessels and the fibrous framework are filled with fat. Covering the 

 inferior surface of the fibrous fro^^s and the plantar face of the pedal bone we 

 find a modification of the coronet; namely, the velvety tissue. The surface 

 of the velvety tissue is much the same as that of the coronet, being covered 

 ■with papillye of much the same size ; the largest papilla3 are found towards the 

 external borders of the plantar surface, and the shortest are found in the cleft 

 of the fibrous frog; they are all lodged in the minute pores we find upon the 

 superior face of the sole of the hoof. The horny sole is secreted by the velvety 

 tissue. 



Upon the anterior face of the pedal bone, covering a portion of the lateral 

 cartilages, extending backwards and covering the wings of the pedal bone, 

 and finally reflected onto a portion of the plantar face, is the laminal tissue, 

 or the sensitive lamina?; this portion of the horn-secreting membrane owes 

 its name to the leaves, or folds, which we find upon its surface. The leaves, 

 or lamina^ are from five hundred to six hundred in number, run parallel 

 with each other and are separated by deep channels, into which are dove- 

 tailed analogous leaves on the inner surface of the wall of the hoof. The 

 sensitive laminjB extend from the inferior border of the coronet, — where they 

 do not project to so great a degree, — to the plantar border of the foot, where 

 they each terminate in five or six large papillar prolongations which are lodged 

 in the horny pores at the circumference of the sole ; they increase in width 

 from above to below ; their free margin is finely denticulated or toothed, while 

 the sides are traversed by folds, about sixty in number, which pass without 

 interruption from top to bottom. The sensitive laminas are not directly in 

 contact with the long lan^inffi of the wall of the hoof, there being a layer of 

 soft rounded cells between the two. The sensitive lamina? have much the 

 same structure as the velvety tissue ; they are immense flattened papilla?, and 

 are among the principal instruments of touch in the horse's foot; they in re- 

 ality play a mechanical part in concurring by their dovetailing with the horny 

 laminoe, to assure the solidity of the union of the hoof pith the living parts. 



The horn of the hoof has, except in the horny lamina?, a fibrous structure 

 throughout; it is perforated by cylindrical canals whose upper end is funnel 

 shaped, and contains the papilla? of the matrix, as Ave have already found 

 to be the case : whether they belong to the coronet, or to the velvety tissue 

 of the sole, the lower end reaches the inferior border of the wall or lower 

 face of the sole or frog, they are rarely met with in the horny lamina?. The 

 spaces between the canals are filled by concentric layers of flattened cells. 

 The hoof being a dependency of the epidermis or outer layer of the skin is 

 developed like it, by the incessant formation of cells in the layer that cor- 

 responds to the rete mucosum of the skin, at the expense of plasma thrown 

 out by tiie numerous vessels in the horn-secreting membrane. In this way the 

 papilla? are constantly forming layers of cells, which, one after the other, are 

 crowded in a downward direction ; and it is this secretion by the papilla? that 

 gives the horn its fibrous appearance. The function of the papilla? is com- 

 pleted by the exhalation of a particular fluid, which maintains the flexibility 

 of the hoof, and probably by the development of a quantity of cells found 

 ■within the canals. 



Tiie sensitive lamina? do not, in the normal condition, concur to* any extent 

 in the development of the wall; the cells covering tiicm are multiplied in 

 describing a downward and forward movement, and though they are applied 

 to the inner face of the wall, they do not constitute the horny lamina? : the 

 latter are formed at the coronet, at the commencement of the sensitive 



