THE FOOT AND SHOEING. 221 



united, but a prolonged soaking of the dead hoof will cause complete 

 separation at the " white line," which is then clearly seen to be a con- 

 tinuation downwards of the horny leaves. The horny sole grows from 

 the fleshy sole, its fibres slanting in the same direction as those of the 

 wally but unlike the latter, on attaining a definite length varying from a 

 quarter to about three-quarters of an inch, they separate from the parts 

 above, and shell out of the hoof. This natural provision prevents over- 

 growth of the sole, which therefore requires little attention from the 

 farrier. The horn of this part is softer than the wall, but harder than 

 the frog. 



The f7'0g is a thick, wedge-shaped piece of horn, fitted point foremost The frog. 

 into the space between the angles of the heels. Its centre is the seat of a 

 marked depression, the " cleft," the depth of which, in the shod hoof, is 

 often exaggerated into a deep crack. The horny frog grows from the 

 fleshy frog above it ; like the wall its fibres are continuous, and do not 

 shell out as do those of the sole. Its consistency should be that of firm 

 indiarubber, tough, and very elastic. 



The Functions of the Parts. 



The bones^ as in other structures, give solidity, and form an internal The 

 scaffolding on which the soft parts can be securely based. bones. 



The cartilages^ extending as they do beyond the wings of the pedal The 

 bone and curving round the back of the foot, are evidently designed cartilages, 

 to contain and support the elastic cushion of the heels ; and, while 

 they are sufficiently rigid to prevent undue bulging of the parts, they 

 are springy enough to yield to changes of form when under pressure 

 from the weight of the horse, and return to their original position when 

 this is removed. 



The te?tdo?is, acting as ropes on which the muscles above pull, alter The 

 the position of the bones, for the different movements required. The tendons. 

 one in front (the extensor) straightens the column of bones, and 

 slightly turns up the toe, for forward movement : those at the back 

 (flexors) bend the bones on each other, to allow the leg to be raised. 



The blood supply is so bountiful, that in addition to giving nourish- The blood. 

 ment to the foot, it acts like a water bed, helping to equalise the 

 tremendous pressures to which the whole structure is constantly sub- 

 jected, and keeping the bones and sensitive parts contained in the hoof 

 buoyantly supported, like a big ship in a little dock. 



