THE FOEE-FEET. 71 



with the heels of the crust, the same effect must be 

 produced upon them." This theory is very beautiful ; 

 but I believe, ^vith Ximrod, that a bit of spongy sub- 

 stance, such as the elastic frog of a horse, has very 

 little chance of resisting the united pressure of iron 

 and horn. In short, it is not to be supposed that an 

 elastic substance, which must yield to pressm-e, could 

 act as a wedge, in expanding hard and solid materials 

 like the bars and crust of a horse's hoof. Whatever 

 may be the use of the frog, I am certain this is not it. 

 No man would attempt to split a block of wood by a 

 wedge of india-rubber, Why, then, are we to suppose 

 that the elastic frog acts as a wedge ? I cannot pre- 

 tend to detei-mine all its functions, but I believe it has 

 a great deal to do in keeping the delicate parts which 

 are placed above it in a healthy, natural condition. 



So far from acting like a wedge, the frog probably 

 fulfils the opposite duty. When the weight of the 

 horse comes down on the bones of the foot, they have 

 a tendency to sink ; the soft parts underneath them 

 press downwards on the top of the frog; the frog, 

 being elastic, yields to the pressm-e, and becomes di- 

 minished in bulk, at the same time that it descends a 

 little from its position, and thus, to a certain extent, 

 makes room for the temporary descent of the internal 

 parts. When the pressure is removed, it springs up 

 again, by virtue of its elasticity, into its original 

 place. 



