286 THE HORSE. 



nor would the foot have so secure a hold. Then if the sole be naturally 

 hollow, and hollow because it mnst descend, the smith must not interfere 

 with this important action. When the foot will bear it, he must pare out 

 sufficient of the horn to preserve the proper concavity, a small portion at 

 the toe and near the crust, and cutting deeper towards the centre ; and 

 he must put on a shoe which shall not prevent the descent of the sole; 

 which not only shall not press upon it, but shall leave sufficient room be- 

 tween it and the sole to admit of this descent. If the sole is pressed upon 

 by the coffin-bone, by the lengthening- of the elastic leaves, and the shoe 

 will not permit its descent, the sensible part between the coffin-bone and 

 the horn will necessarily be bruised, and inflammation and lameness will 

 ensue. It is from this cause, that if a stone insinuates itself between 

 the shoe and the sole, it produces so much lameness. Of the too great 

 concavity of the sole, or the want of concavity, we shall treat when we 

 arrive at the diseases of the foot. 



THE COFFIN BONE. 



We proceed to the interior part of the foot. The lower pastern, a small 

 portion of which (see d, page 249) is contained in the horny box, has 

 been already described. Beneath it, and altogether inclosed in the hoof 

 is the coffin-bone, or proper bone of the foot, (see/ page 249, and cZ, 

 fig. 1, page 253). It is fitted to, and fills the fore part of the hoof, 

 occupying about half of it. It is of a light and spongy structure (see d, 

 fig. 1, page 253), and filled with numerous holes. Through these pass the 

 blood-vessels of the foot, which are necessarily numerous, considering the 

 important and various secretions there carrying on, and the circulation 

 through the foot it is plain could not possibly be kept up, if these vessels 

 did not run through the substance of the bone. The holes about the body of 

 the coffin-bone convey the blood to the little leaves with which it is covered ; 

 those near the lower part go to the sole. Considering the manner in 

 which this bone is inclosed in the horny box, and yet the important 

 surfaces around and below it which are to be nourished with blood, the 

 circulation which is thus carried on within the very body of the bone is 

 one of the most beautiful provisions of nature that is to be found in the 

 whole of the frame. No inconvenience can arise from occasional or 

 constant pressure, but the bone allows free passage to the blood, and 

 protects it from every possible obstruction. 



The fore-part of the coffin-bone is not only thus perforated, but it is 

 curiously roughened for the attachment of the numerous little leaves about 

 to be described. On its upper surface it presents a concavity for the head 

 of the lower pastern, p. 253. In front, immediately above d, is a striking 

 prominence, into which is inserted the extensor tendon of the foot. At the 

 back e, p. 249, it is sloped for articulation with the navicular bone, and 

 more underneath, is a depression for the reception of the perforating flexor 

 tendon, m, continued down the leg, passing over the navicular bone at n, 

 and at length inserted into this bone. On either side, as seen p. 254, 

 are projections called the wings, or heels of the coffin-bone, and at the 

 bottom' it is hollowed to answer to the convexity of the internal part of the 

 sole. 



That which deserves most attention in the coffin-bone is the production 

 of numerous little leaves round its front and sides. They are prolongations 

 of the thick and elastic membrane covering the coffin-bone, and consist 

 of cartilaginous, fleshy plates, proceeding from it, running down the coffin- 



