804 THE APPARATUS OF THE SENSES. 



size is greatest towards the lower part of the cushion ; those of the perioplic 

 ring are smallest. Contained within the minute apertures at the upper part 

 of the wall, these papillae, considered as a whole, and when the hoof has been 

 removed by maceration, form a tufty surface most perfectly seen when the 

 foot is immersed in water. 



The structure of the coronary cushion resembles that of the derma, of 

 which it is in reality only a continuation. It comprises a fibrous frame- 

 work, remarkable for its thickness and its condensation, with a considerable 

 number of vessels and nerves, whose ramifications may be followed to the 

 extremity of the villi. It owes to its great vascularity the bright red colour it 

 shows on its surface ; this colour is sometimes masked by the black pigment 

 belonging to the mucous portion of the hoof. 



(I have found a notable quantity of adipose tissue in the cushion.) 



2. VELVETY TISSUE. Much thinner than the plantar cushion, the vel- 

 vety tissue, the formative organ of the sole and frog, extends over the whole 

 of the plantar region of the third phalanx, as well as the plantar cushion, 

 whose bulbs and pyramidal prominence it covers by adapting itself exactly 

 to the irregularities of this elastic mass. 



Its surface, which altogether resembles the general configuration of the 

 plantar surface of the hoof, is divisible into two regions : a central, corre- 

 sponding to the pyramidal body and the frog, and continuous on the bulbs 

 of the cushion with the extremities of the coronary cushion and the perioplic 

 ring, but chiefly with the latter ; the other, peripheral, is covered by the 

 horny sole, separated from the podophyllous tissue by the plantar border of 

 the foot, somewhat encroached upon posteriorly by the laminae corresponding 

 to the bars, and is continuous, above these laminge, with the plantar cushion. 



The surface of the velvety tissue is studded with villi similar to those 

 of the coronary cushion, and about the same in size. The longest are 

 towards the circumference of this surface, and the shortest in the median 

 lacuna of the pyramidal body ; all are lodged in the porosities on the inner 

 surface of the horny sole and frog. 



This tissue shows the same organisation as the coronary cushion. The 

 vascular corium, forming its base, is thickened at its peripheral portion by 

 a fibrous network named the plantar reticulum, in the meshes of which are 

 sustained the veins of the inferior face of the foot. 



3. LAMINAL TISSUE. This part of the keratogenous membrane is also 

 very frequently designated the podophyllous tissue (and still more frequently, 

 in this country, as merely the lamina). It is spread over the anterior face 

 of the third phalanx, occupying the interval between the plantar border of 

 that bone and the lower margin of the coronary cushion ; its width is, 

 therefore, greater at the anterior part of the phalanx than on its sides, where 

 the extremities of the membrane are reflected below the bulbs of the plantar 

 cushion on to the velvety tissue. 



This membrane owes its name to the leaves it exhibits on its superficies ; 

 these are from five to six hundred in number, run parallel to each other, 

 and are separated by deep channels, into which are dovetailed analog 

 leaves on the inner side of the wall of the hoof ; they extend from the whii 

 zone that limits the inferior border of the coronary cushion where they 

 not so salient to the plantar border of the foot, where they each terminate ii 

 five or six very large villous prolongations, which are lodged in the honrj 

 tubes at the circumference of the sole. 



The leaves (laminae,) of the podophyllous tissue increase in width froi 

 above to below ; their free margin is finely denticulated, and, under 



