84 The Management and Treatment of the Horse, 



rising of the frog. The preservation and usefulness of 

 the limbs of the horse are chiefly maintained by this 

 upward expansion. Brown, in his writings, says 

 that "by long-continued pressure on the frog in 

 draught horses, and conveyed from the frog to the 

 cartilage, inflammation is set up and the cartilages 

 turned into bone, viz., sidebone." In this I differ with 

 him, and am of opinion that the more the horse treads 

 upon the frog the better the foot becomes by the 

 attrition. I do not believe that any horse ever had 

 sidebone by treading upon the frog. I believe that he 

 may have them by his heels being elevated by a thick 

 shoe, and all the natural pressure taken off the frog 

 and thrown upon the bars and crust, and by the frog 

 being cut away to make its feet look nice, as if Nature 

 was not in itself perfection. From inferior and 

 posterior sides of the true cartilages, two fibro-car- 

 tilaginous processes extend in a forward direction 

 towards the heels of the coffin-bone. They spread 

 inwards upon the surface of the tendo-perforans, 

 become united at their inner sides with the superior 

 margin of the sensitive frog, are covered inferiorly by 

 the sensitive sole, and at the same time assist in the 

 support of the sensitive frog. They are triangular in 

 form and are arched in the same manner as the sole. 

 Their use appears to be to fill up the triangular vacant 

 spaces left between the tendo-perforans and the 

 heels of the coffin-bone, thereby completing the surface 

 of support for the frog, and extending that for the 

 expansion of the sole. The navicular bone is a small 

 bone resembling a weaver's shuttle and has a side-to- 



