THE IMPROVED ART OF FARRIERY. 283 



The frog is a very important part of tlie hoof, inas- 

 mach as it forms an elastic cushion for the protection 

 of that part of the tendon of the leg which terminates 

 and attaches itself to the inferior surface of the coffin- 

 bone by a broad expansion of its fibres, anatomically, 

 the aponeurosis. 



Its form is that of a wedge, and which is admirably 

 adapted to give the foot stability by its resistance when 

 indented in the earth. It has been supposed to be es- 

 sential to the purpose of keeping the heels at a proper 

 distance from each other, and thereby to prevent con- 

 traction ; but this opinion does not appear to be well 

 founded, because the frog is composed of a substance 

 much softer than the heels, and consequently less ca- 

 pable of performing that office than if it were more 

 dense in its texture. 



It is very subject to disease when the horse is kept 

 in the stable, and it is also frequently found in an im- 

 perfect state even amongst colts at grass. It is gene- 

 rally larger and healthier in flat feet than in those that 

 are concave, and this arises from its being more ex- 

 posed to pressure, by which means its healthy action 

 is maintained, and any accumulation of superfluous 

 moisture is prevented from taking place. The natural 

 state of the hoof is kept up solely by an equal growth 

 in all parts. Whenever this growth becomes irregular 

 and unequal, an alteration of form naturally ensues. 

 Thus, when the wall is too strong, it overpowers the 

 resistance of the sole, which in consequence is rendered 

 more concave, and the heels are forced closer together. 

 But when the wall is too weak, the sole, in process 

 of time, descends to the ground and becomes flat, and 

 sometimes convex. In this case the foot is more ex- 

 panded at the bottom ; but in proportion with that ex- 

 pansion it will be more or less contracted above at the 



