AZ^D HOW :0 KEEP IT SOUND. 9 



cannot descend lower ; and the sensible sole above, becoming 

 squeezed between the edges of the coffin bone and the horn, 

 produces inflammation, and perhaps abscess. The eriect of 

 this squeezing of the sensible sole is most commonly wit- 

 nessed at the angle of the inner heel, where the descending 

 heel of the coffin bone, forcibly pressing the vascular sole 

 upon the horny sole, ruptures a small blood-vessel, and pro- 

 duces what is called a corn, but which is, in fact, a bruise. 



The horny frog occupies the greater part of the triangular 

 space between the bars, and extends from the hindermost 

 part of the foot to the centre of the sole, just over the point 

 where the bars meet ; but is united to them only at their 

 upper edge : the sides remain unattached and separate, and 

 form the channels called the "Commissures."* 



The frog is evidently designed for very important uses ; 

 but, as our object is purely practical, and not speculative, we 

 will not stop to inquire, whether its chief office is to expand 

 the foot, and prevent contraction or not — which is debatable 

 ground — but proceed to consider it in a point of view bearing 

 more usefully on our subject, viz., as the part which offers 

 us the best criterion whereby to judge of the effect of our 

 shoeing upon the foot generally ; for no part undergoes so 

 much change from bad shoeing, or exhibits it so soon, as the 

 frog. If we carefully observe the form and size of the frog 

 in the foot of a oolt of from four to five years old, at its first 

 shoeing, and then note the changes which it undergoes as the 

 shoeings are repeated, we shall soon be convinced that a 

 visible departure from a state of health and nature is taking 

 place. At first it will be found large and full, with consider- 

 able elasticity ; the cleft oval in form, open, and expanding, 

 ■^ith a continuous, well-defined, and somewhat elevated boun- 

 cary ; the bulbs at the heels fully developed, plump, and 

 rounded ; and the whole mass occupying about one-sixth of 

 the circumference of the foot.f By degrees the fulness and 

 elasticity will be observed to have diminished; the bulbs at 

 the heels will shrink, and lose their plumpness ; the cleft will 

 become narrower, its oval form disappear, the back part of 

 its boundary give way, and it will dwindle into a narrow 

 crack, extended back between the wasted, or perhaps obliter- 

 ated bulbs, presenting only the miserable remains of a frog, 

 such as may be seen in the feet of most horses long accus- 

 tomed to be shod. 





Page 47, fig. 1. t Ibid. 



